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368 Cards in this Set
- Front
- Back
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Who has the most species?
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Insects
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Which group (phylum) has the most individuals?
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Nematodes
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How many different animal species are there?
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1.5 million
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Who founded the study of taxonomy?
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Carolus Linnaeus (1707-1778)
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What is the branch of biology that classifies organisms?
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Taxonomy
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What did Linnaeus interpret? What was this evidence of?
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He interpreted organismal adaptations. Evidence that the Creator had designed each species for a specific purpose.
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What three components can make up a sort of definition of evolution? (Clicker Question)
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Survival of the fittest
Descent with modification Change in gene expression |
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What was significant about Lamarck's hypothesis on the evolution of species?
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Species evolve through use and disuse of body parts and inheritance of acquired traits.
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Why was Lamarck's hypothesis on the evolution of species wrong?
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He believed that evolution was through use and disuse of acquired traits, which we know to be incorrect.
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Who was the first scientist to look at geology in a systematic way?
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Hutton
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What were the two components of Hutton's theory of the Earth based on geological change?
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1) Idea of gradualism (Earth takes time to create)
2) Idea of uniformitarianism (same processes are occurring across time) |
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What did Hutton study to produce his theories?
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Layers of rock from deposited sediment in oceans and other bodies of water which would build up above sea level... Rivers and other things would erode the rocks and allow him to study the strata which contained fossils from the time when the stratum was formed.
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Who is the Father of Geology?
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Lyell
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Lyell, like Hutton, studied sediment layers, but what else did he make a point of studying?
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Layers of magma from volcanoes
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Who is the Father of Paleontology?
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Cuvier
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Cuvier did a systematic study of what?
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Fossils
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What are fossils? Where are they found? How does this help classify them?
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Remains or traces of organisms from the past, usually found in sedimentary rock, which appear in layers or strata. By determining the age of the layers, one can determine the age of the fossils.
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Who was Charles Darwin's grandfather? What was his family motto?
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Erasmus Darwin;
Everything from Shells (Evolution!) |
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What did Charles Darwin do on his voyage of the Beagle?
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Collected specimens, observed adaptations of plants and animals that inhabited many diverse environments.
Traveled to Galápagos Islands and studied finches |
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Why didn't Charles Darwin publish his essay on the origin of species and natural selection right away when he wrote it in 1844?
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Predicted an uproar from public.
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Who came up with a very similar theory to the "Origin of Species" and the mechanism of natural selection, prompting Darwin to get his essay published in 1858 (14 years later)?
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Alfred Wallace, naturalist from South America
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Was Darwin the first person to propose the idea of evolution?
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No, Lamarck (even though he was partially incorrect in his his theory)
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What is the 1st of Darwin's observations?
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Members of a population often vary greatly in their traits.
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What is the 2nd of Darwin's observations?
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Traits are inherited from parents to offspring.
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What is the 3rd of Darwin's observations?
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All species are capable of producing more offspring than the environment can support.
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What is the 4th observation from Darwin?
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Owing to lack of food or other resources, many of these offspring do not survive.
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In order for evolution to work, what two things must occur?
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Variability and heritability
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What two aspects that are required for evolution are shown in this graph?
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Variability (x-axis or y-axis)
Heritability (correlation) |
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Which person was very important for helping Darwin make the connection to Observation #4 (not enough resources for all offspring to survive)?
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Economist: Thomas Malthus:
- Believed that human suffering was inescapable consequence of human's ability to reproduce faster than resources could provide for. - Darwin generalized to ALL species |
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What was inference #1 from Darwin?
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Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals.
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What was inference #2 from Darwin?
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This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations...
Relative Fitness |
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What is the best, most concise definition of evolution?
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Descent through modification.
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What are the 6 aspects of evidence for evolution?
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1) Artificial Breeding (domestic animals)
2) Biogeography (Galápagos Islands) 3) Fossil Record 4) Homology between Species (similarities across species) 5) Embryology (6) Molecular Biology - not available to Darwin) |
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What is the term that accounts for the similarity in bone structure of these different species:
Human arm, cat arm, whale fin, bat wing? |
Homology
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What evolves?
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Populations; not individuals (Lamarck thought otherwise)
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What does natural selection do to heritable traits in a population?
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Either increases of decreases the frequency.
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Adaptations can vary in species in what?
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Different environments
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What was the only evolutionary mechanism that Darwin recognized?
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Natural Selection
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How did Darwin think that heritable processes occurred? Compared to Mendel?
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Darwin: Infinitely small changes over many years (slow process); quantitative.
Mendel: He changed favorable traits quickly; qualitative. |
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What type of changes does the fossil record account for? (Changes in species; above species level)
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Macroevolutionary
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What deals with changes in gene frequencies in a population over generations (below species level)?
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Microevolution
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How do scientists determine the age of fossils?
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Using half-lives of naturally radioactive isotopes by looking at the relationship between the decay product and decay of radioisotope.
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How do you know there wasn't any "decay product" (Argon-40 gas) in the rocks to begin with?
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Check rock / lava of modern volcanoes; no decay product (Argon-40) until the radioactive isotope (Potassium-40) decays.
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What is the exponential decay equation?
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N = No e^ -λt
N: amount of parent left No: initial parent material (time = 0) λ: rate of decay t: time |
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What is the half-life equation?
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t1/2 = ln2 / λ
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What is the equation to determine the amount of daughter?
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D = No - N
No: initial parent material (time = 0) N: amount of parent left |
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What equation do you use when there is some of the daughter isotope in the initial rock?
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Isochron Equation (divide by non-radioactive isotope)
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What is the slope of the isochron equation? What does it tell you?
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e^λt - 1
Age of fossil. |
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What techniques are used to put together a timeline of the history of the Earth?
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- Radioactive isotope half-lives
- Tree-ring dating - Vostok ice core data - Varve (layers in rock) - Magnetic field fluctuations |
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What does the isochron method allow you to calculate?
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The age of the rock despite not knowing the initial amount of radioactive substance.
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What is carbon dating useful for?
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More recent materials (approx. 75,000 years old)
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Why doesn't carbon dating require isochrons?
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C14 replenishes itself constantly (little fluctuation); doesn't decay until something dies - stops taking in new C14.
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What are the three eons? What are the time periods?
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1. Archaean (4.5 bya - 2.5 bya)
2. Proterozoic (2.5 bya - 600 mya) 3. Phanerozoic (600 mya - now) |
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When was the origin of the earth?
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4.5 bya (archaean eon)
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When did the first prokaryotic fossils show up? What were they found in?
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3.5 bya in stromatolites (layered rocks that form when certain prokaryotes bind thin films of sediment together)
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When did the concentration of atmospheric oxygen begin to increase? Who brought it about most likely? How?
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2.7 bya
(cyanobacteria; produced during the water-splitting step of photosynthesis) |
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When did the first eukaryotic (unicellular) fossils appear?
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2.1 bya
(endosymbiosis of other small prokaryotes engulfed in prokaryotes - eventually forming a single organism) (may have appeared as early as 2.5 bya - right at beginning of Proterozoic) |
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When did the first multicellular eukaryotes appear? Fossils?
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1.5 bya (multicellular eukaryotes)
1.2 bya (first fossils of multicellular eukaryotes) |
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When did the first animals appear?
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565 mya in Ediacaran Period
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When did the first fossils of multicellular eukaryotes - algae appear?
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1.2 bya
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When was the Ediacaran Period? What was the significance of this period? When was the significant portion?
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The end of the proterozoic era (635 - 542 mya)
Numerous animal fossils discovered (565 - 542 mya) after "snowball earth" thawed |
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What are the 6 periods in the Paleozoic era of the Phanerozoic eon?
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1) Cambrian (542)
2) Ordovician (500) 3) Silurian (420) 4) Devonian (375) 5) Carboniferous (350) 6) Permian (275) (Can Old Sailers Date Curvaceous Petunia?) |
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What are the three eras of the Phanerozoic Eon?
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1) Paleozoic (542 mya - 251 mya)
2) Mesozoic (251 mya - 66 mya) 3) Cenozoic (66 mya - now) |
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When did the Cambrian explosion occur? What happened?
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At the beginning of the phanerozoic eon, paleozoic eon, cambrian period (542 mya)
Sudden increase in diversity of many animal phyla - prey / predators (natural selection). Best described by Burgess Shale fossils. |
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What happened during the Ordovician period? When?
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Colonization of land by diverse fungi plants, and animals (500 mya)
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What happened during the Silurian period? When?
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Diversification of vascular plants (420 mya)
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What happened during the Devonian period? When?
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Tetrapods (animals on four legs) appear (375 mya)
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What happened during the Carboniferous period? When?
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First seeds appear (350 mya)
(Seed ferns existed at this time, but are now extinct - responsible for coal deposits) |
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When was the Permian period?
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275 mya
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During which era did Pangaea exist?
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Paleozoic Era (Phanerozoic eon)
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What are the three periods of the Mesozoic era?
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1) Triassic (250)
2) Jurassic (200) 3) Cretaceous (150) |
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What was significant in each of the Mesozoic eras (triassic, jurassic, cretaceous)?
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Triassic - Mammals originate (dinos, huge plants)
Jurassic - Gymnosperms (dominant plants) / Dinosaurs Cretaceous - Flowering plants |
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What happened during the Cenozoic era? When?
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Mammals, birds, and insects radiate to many species (65 - present)
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What is the study of fossil tracks?
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Ichnology - useful for studying tetrapods (originated during Devonian period)
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When were the 5 main extinctions?
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1) end of Ordovician - Silurian
2) end of Devonian - Carboniferous 3) end of Permian (paleozoic) - Triassic (mesozoic) 4) end of Triassic - Jurassic 5) end of Cretaceous (mesozoic) - Cenozoic era |
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What is the significance of mass extinctions?
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End of many species leads to the development of many new species (fill empty niche, new species created, variation, competition, natural selection).
Increased ratio of predators. |
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What is adaptive radiation?
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Evolution of diversely adapted species from a common ancestor upon introduction to new environmental opportunities.
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What are the three main continental periods? (Names of land mass(es) and when they occurred)
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1) Pangaea - Paleozoic
2) Laurasia & Gondwana - Mesozoic 3) Continents - Cenozoic |
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Do individuals and populations evolve?
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No. Individuals do not evolve. Populations do.
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What is the method for determining the absolute ages of rocks and fossils, based on the half-life of radioactive isotopes?
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Radiometric Dating
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What is the hypothesis for the origin of eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria, chloroplasts, and perhaps other cellular structures were derived from small prokaryotes that had been engulfed by larger cells.
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Serial Endosymbiosis
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What is the evolutionary change in the timing or rate of an organism's development? (similarities / differences in development)
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Heterochrony
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What is an example of heterochrony?
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Comparison of chimpanzee and human skulls; as fetus the skulls are similar, as they develop into adults the skulls differentiate.
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Is evolution goal-oriented?
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NO! Evolution is NOT goal-oriented. New, complex biological structures evolve through a series of incremental modifications (to features already present), each of which benefits the organism that possesses it.
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What are homeotic genes?
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Master regulatory genes that determine how basic features are arranged.
In animals: Hox genes. Involved in the development of body components that are shared in many species. |
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How are invertebrates differentiated from vertebrates in regards to their Hox genes?
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(Invertebrates) have 1 Hox cluster of "homeotic genes" on a chromosome.
One duplication results in 2 Hox clusters (jawless vertebrates). Two duplications results in 4 Hox clusters (vertebrates w/ jaws: mammals). |
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Phenotypic variation is not in direct relation to genotype (non-heritable variation). Give an example.
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Differences in caterpillar appearance can be accounted for by diet.
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Geographic variation occurs in isolated populations. Provide two examples.
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Mice from different parts of an island have different karyotypes (chromosome pairs fused in different ways).
Allele variation in fish by latitude (temperature) |
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What are two sources of variation that a population can act upon?
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1) Mutations
2) Sexual Reproduction |
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What are the two varying effects of point mutations?
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1) Mutations that result in protein production are often harmful
2) Sometimes can increase the fit between organism and enviornment |
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Duplicated genes (small: sometimes less harmful) increase the genome size and can do what?
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Take on new functions by further mutations.
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What are four rules of natural selection?
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1) Selection can act only on existing variations
2) Evolution is limited by historical constraints (genes that are already there) 3) Adaptations are often compromises (no perfect organisms) 4) Chance, natural selection, and the environment interact |
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What does the Hardy-Weinberg Equilibrium mean?
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Frequencies of alleles and genotypes in a population will remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work.
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How do you determine whether natural selection or other factors are causing evolution?
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Use the Hardy-Weinberg principle; if the same ratio of alleles before and after a generation (or more) occurs, then there is no natural selection.
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The Hardy-Weinberg Model is also called what?
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The Null Model
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What are the five assumptions required for the Hardy-Weinberg Equilibrium?
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1) No natural selection (no evolution)
2) No mutations (no evolution) 3) No gene flow (no migration into our out of gene pool) 4) No genetic drift (extremely large population size) 5) Random mating |
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If the 5 assumptions of the Hardy-Weinberg Equilibrium are not met, what happens?
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Microevolution
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What are the 5 ways in which evolution can occur?
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1) Natural Selection
2) Mutations 3) Gene flow (moving alleles into or out of the gene pool) 4) Small population sizes (genetic drift) 5) Non-random mating |
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What is the only adaptive component of evolution?
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Natural selection
(Other modes of evolution could be detrimental: mutations, gene flow, genetic drift, nonrandom mating) |
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What are the two modes of genetic drift?
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1) Bottleneck effect
2) Founder effect |
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What is the founder effect?
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When a subset of a population have a higher frequency of an allele than the greater population and move to a new environment to establish a new population.
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What is the bottleneck effect?
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Some environmental factor eliminates a large amount of the population and by chance only a certain phenotype is left or predominates.
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In what type of populations is genetic drift significant?
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Small populations (changes allele frequencies substantially)
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Genetic drift causes what to happen to allele frequencies?
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To change at random (not for adaptive purposes).
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Why can genetic drift be harmful? (2)
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Loss of genetic variation within populations.
Can cause harmful alleles to become fixed. |
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What is the term for the movement of alleles among populations?
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Gene flow
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What is the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals?
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Relative Fitness
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What are the two components of relative fitness?
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Ability to survive (so you can produce offspring)
Reproductive success (compared to other individuals in population) |
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What does selection favor (genotype or phenotype)?
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Selection favors certain genotypes by acting on the phenotypes of certain organisms.
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What are the three modes of selection?
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1) Directional selection
2) Disruptive selection 3) Stabilizing selection |
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What is the type of selection occurring in this situation:
Selection shifts the overall makeup of the population by favoring variants that are at one extreme of the distribution. |
Directional Selection
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What is the type of selection occurring in this situation: Selection favors variants at both ends of the distribution; intermediate traits are at a disadvantage.
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Disruptive Selection
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What is the type of selection occurring in this situation:
Selection removes extreme variants from the population and preserves intermediate types. |
Stabilizing Selection
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What is natural selection that occurs where certain individuals have more mating success?
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Sexual Selection
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What are the two types of sexual selection? Describe.
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1) Intra-Selection - selection within one sex (one sex competing with one another for a mate of the opposite sex)
2) Inter-Selection - "Mate Choice" - individuals of one sex are choosy in selecting their mates from the other sex |
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What are marked differences between the two sexes in secondary sexual characteristics that are not directly associated with reproduction or survival (such as size, ornamentation, and behavior)
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Sexual Dimorphism
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When female peacocks select the male peacock with the best ornamentation, what kind of sexual selection is that?
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Inter-sexual selection.
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What is occurring in these pictures?
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Sexual selection is occurring in males
(the more mates they select, the more offspring they produce) |
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What is the source of alleles?
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Mutations
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What is an example of heterozygote advantage (when the heterozygote has a greater fitness than both kinds of homozygotes)?
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Malaria - heterozygous for the sickle-cell trait (no malaria or sickle-cell)
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What is frequency-dependent selection? Example?
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The frequency of a phenotype declines in a population if it becomes too common in the population.
Right mouthed fish vs. left mouthed fish. (Eat all of one side of fish) |
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What type of selection is depicted by this graph?
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Frequency-Dependent Selection
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What is the type of variation that appears to confer no selective advantage or disadvantage?
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Neutral variation
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Where does neutral variation occur? (2)
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1) Noncoding regions of DNA
2) In proteins that have little effect on protein function or reproductive fitness |
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Why are the majority of point mutations harmless?
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- much of the DNA in genomes does not code for proteins
- redundancy of genetic code (amino acid may still be the same, or even if not, may still not affect shape and function) - may make it better suited for environment |
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How does sexual recombination generate genetic variability?
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3 Mechanisms: crossing over, independent assortment of chromosomes, fertilization
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What is a group of individuals of the same species that live in the same area and interbreed to produce fertile offspring?
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Population
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What is a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but do not produce viable, fertile offspring with other such groups?
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Species
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What is the aggregate of all of the alleles for all of the loci in all individuals in a population?
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Gene pool
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If there is only one allele for a particular locus in a population, what is the allele called?
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Fixed
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What are the equations involved with the Hardy-Weinberg Model?
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p + q = 1
p^2 + 2pq + q^2 = 1 p = frequency of dominant allele q = frequency of recessive allele |
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What does the biological concept of species emphasize?
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Reproductive isolation
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What does the morphological concept of species emphasize?
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Similarity of traits - must be careful, different species may look identical, members of a species may look very different
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What allows a species consisting of several distinct populations to maintain its identity as a species?
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Gene Flow
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What are barriers that impede members of two species from producing viable, fertile offspring?
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Reproductive Isolation
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What are the five types of prezygotic barriers (reproductive isolation)? Explain each briefly.
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1) Habitat Isolation - species that occupy different habitats
2) Temporal Isolation - species that breed during different times 3) Behavioral Isolation - courtship rituals that enable mate recognition 4) Mechanical Isolation - mating is attempted, but morphological differences prevent it 5) Gametic Isolation - sperm of one species may not be able to fertilize the eggs of another species |
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What are the three types of postzygotic barriers (reproductive isolation)? Explain each briefly.
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1) Reduced Hybrid Viability - impairs hybrid's development or survival
2) Reduced Hybrid Fertility - hybrid is sterile 3) Hybrid Breakdown - after first generation, offspring can't survive or are sterile |
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What are the two types of speciation?
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1) Allopatric - geographically isolated
2) Sympatric - no geographic barrier |
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What is an example of allopatric speciation?
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Two separate species of squirrels on opposite sides of the Grand Canyon
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In the salamander example, the further geographically the different salamanders were from each other, the greater the degree of what?
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Reproductive Isolation
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Which type of speciation has more species typically? Which has fewer?
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More species = allopatric (geographic barriers)
Less species = sympatric (w/o geographic barrier) |
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What factors can lead to sympatric speciation? (3)
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Gene flow reduced by:
1) polyploidy 2) habitat differentiation 3) sexual selection |
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What happens during polyploidy? What are the two kinds? Where are they most likely to occur?
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An accident of cell division leading to a chromosomal change in which the organism possesses more than two complete chromosome sets.
Autopolyploidy & Allopolyploidy. Most common in plants; can occur in some animals. |
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What differentiates autopolyploids from allopolyploids?
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Autopolyploids have more than two chromosome sets that are from a single species
Allopolyploids have more than two chromosome sets that are from two different species |
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How do autopolyploids occur?
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Failure of cell division after chromosome duplication gives rise to tetraploid.
Gametes produced are diploid. (Offspring with tetraploid karyotypes may be viable and fertile) |
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Where do autopolyploids typically occur? Why?
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Plants because they can self-pollinate (therefore not having to wait for another "incorrect" gamete to mate with)
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How do allopolyploids occur?
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Two separate species:
Species A has a meiotic error, unreduced gamete w/ 2n. Hybrid formed with Species B (sterile - set of chromosomes can not pair during meiosis). Can propagate itself asexually (plants) --> fertile polyploid. Only fertile when mating w/ members of same new species (not parents). |
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Wheat used for bread is an example of what kind of polyploidy?
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Allopolyploidy (six sets of chromosomes, two sets from each of three different species).
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What was the example of sexual selection that led to sympatric speciation?
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Coloration of cichlids; females select males based on their appearances, but when they couldn't distinguish between the two species (orange tinted light), they mated with both; therefore, breeding coloration is the main reproductive barrier.
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What are three limitations of the biological species concept?
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1) Cannot easily apply to fossil species
2) Does not apply to asexual species 3) Relies heavily on gene flow as a mechanism |
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What is a hybrid zone?
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A region in which members of different species mate and produce hybrids.
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What are the three outcomes for hybrids in a "hybrid zone"? Explain briefly.
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1) Reinforcement - strengthen reproductive barriers - hybrids cease eventually
2) Fusion - weakening of reproductive barriers - two species fuse 3) Stability - continued production of hybrid individuals |
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Which type of speciation is reinforcement of reproductive barriers most likely to occur in?
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Sympatric species because you learn to distinguish between species (allopatric, if you never see them, can't distinguish).
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When hybrids are less fit than their parents, which type of outcome will occur?
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Reinforcement (of reproductive barriers)
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For fusion of species to occur in a hybrid zone, what must be true?
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The fitness of the hybrids must be at least as fit as the original species.
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What will happen if gene flow is great enough between two parent species of a hybrid?
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Parents will fuse into a single species (breakdown of reproductive barriers).
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What are the two patterns of speciation that can occur over time?
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1) Punctuated pattern - new species suddenly change as they branch
2) Gradual pattern - new species diverge slowly |
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What is the range of time for speciation events to occur?
What is the average time frame? |
4,000 years - 40,000,000 years
average = 6,500,000 years |
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What are the four species concepts?
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1) Biological Species Concept
2) Morphological Species Concept 3) Ecological Species Concept 4) Phylogenetic Species Concept |
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What is the species concept that is described as the sum of how members of the species interact with the nonliving and living parts of their environment? What does it accommodate? What does it emphasize?
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Ecological Species Concept
- accommodates sexual and asexual - emphasizes role of disruptive natural selection as organisms adapt to different environmental conditions |
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What is the phylogenetic species concept?
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A species is the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.
How does one determine the degree of differences required to indicate a separate species? |
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What is the order of taxonomic classification?
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Domain
Kingdom Phylum Class Order Family Genus Species *Keep Personal Computer On For Great Surfing |
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What is a polytomy?
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A branch point from which more than two descendent groups emerge.
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What are sister taxa?
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Groups of organisms that share an immediate common ancestor.
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What do phylogenetic trees show? What don't they show?
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Patterns of descent.
Do not show when species evolved or how much genetic change occurred. |
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What is the definition of phylogeny?
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The evolutionary history of a species or group of species.
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How do you construct a phylogeny?
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Using systematics - a discipline focused on classifying organisms and determining their evolutionary relationships.
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What is occurring when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages.
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Convergent evolution
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What types of data do phylogenies infer from?
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Morphological and molecular data.
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What is another name for shared ancestry?
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Homology
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What is the group called where all of the descendants of a common ancestor are part of the group?
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Monophyletic Group
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What is a group called where not all of the descendants of a common ancestor are included?
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Paraphyletic Group
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What is a group called where there is not one single common ancestor involved? (Descendants from multiple ancestors)
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Polyphyletic Group
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What is it called when a phylogenetic tree has the fewest branches?
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Most Parsimonious
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As the time of divergence increases, what happens to the number of mutations?
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Number of mutations increases.
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What is the method for estimating the time required for a given amount of evolutionary change, based on the observation that some regions of genomes appear to evolve at constant rates?
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Molecular Clock
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If a species has more mutations accumulated, according to the molecular clock, is it older or younger?
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Older, more time for mutations to accumulate.
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Bird and reptiles diverged at about the same time. Therefore, with respect to the Cytochrome C gene of their common ancestor the number of amino acid differences between their cytochrome C protein will be...
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... very similar (same amount of time for mutations to occur, just different mutations).
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According to the molecular clock theory, mutations occur at what kinds of rates?
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Constant
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What is the theory that says that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian selection?
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Neutral Theory
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What are the three domains?
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Eukarya, Archaea, Bacteria
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What is horizontal gene transfer? What are three mechanisms it can occur by?
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A process by which genes are transferred from one genome to another.
1. Exchange of transposable elements and plasmids 2. Viral infection 3. Fusion of organisms |
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How did the domain Eukarya develop possibly?
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Endosymbiosis between an early bacterium and an early archaean (therefore, equally closely related to bacteria and archaea).
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What was the initial understanding of viruses?
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They were contagious fluids.
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What are all viruses made of?
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Protein coat and nucleic acids inside (RNA)
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What are two characteristics of of viruses?
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Infectious
Filterable |
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Where is the genetic information in a virus?
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Viral RNA
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What were the beautiful multi-colored tulips caused by?
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A virus
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What kinds of viruses are?
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DNA or RNA
single stranded or double stranded for both |
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What is the minimum three things all viruses must have?
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1) Coprotein gene (coat)
2) Movement gene 3) Replication gene |
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What is the greatest number of genes a virus can have?
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200-300 genes
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What are the forces of evolution acting on virus populations?
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1) Genetics (mutations, recombination, reassortment)
2) Selection (competition, natural selection) |
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How do viruses generate variety in the genome?
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Mutations, recombination, reassortment.
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Why do viruses have a high mutation rate?
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To generate variability, which allows for selection of better fit individuals in a species.
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What three reasons contribute to virus evolution being so fast?
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1) Fast generation time
2) High rates of fecundity (large # of offspring) 3) High rates of mutation (no repair mechanisms) |
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Why are virus populations called "quasispecies"?
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Because the virus populations are dynamic distributions of nonidentical but related replicons.
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Greatest fitness occurs when mutations approach what? Why?
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The error threshold; too much mutation can lead to loss of vital information, too little mutation can lead to host defenses overcoming the virus.
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What is the slow accumulation of mutations in a population due to constant selective pressure in a single host species?
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Genetic Drift
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When a major genetic change occurs caused by the mixing of genomes derived from two distinct populations of viruses (infect two different species), what has occurred?
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Genetic Shift
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What are the two pathways for virus evolution?
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1) Co-evolution with host
2) Infection of multiple host species |
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What are the advantages and disadvantages of "Co-Evolution with Host"? What types of viruses typically use this pathway?
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Prosperous host = prosperous virus
Virus shares same fate as host (genetic bottlenecks can be fatal). Typical of DNA viruses. |
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What are the advantages of "Infection of Multiple Host Species"? What types of viruses typically use this pathway?
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If one host species is compromised, virus can replicate in another.
Virus cannot optimize for any one situation. Typical of RNA viruses. |
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How does the strength of a virus relate to its chance of transmission?
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More virulent = less chance for transmission (stay in bed)
Less virulent = more chance for transmission (out and about) |
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Which prokaryote causes the most food borne illnesses?
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Campylobactor (exotoxin)
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What is the mechanism that caused the E. Coli we know of to be so bad for us?
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Horizontal Gene Transfer
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What is an ecological interaction between two species in which both benefit?
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Mutualism
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What are the three ecological relationships in which a prokaryote can interact?
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1) Mutualism
2) Commensalism 3) Parasitism |
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What are parasites that cause diseases called?
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Pathogens
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When a prokaryote converts atmospheric nitrogen (N2) to ammonia (NH3), what is this called? What happens to the NH3 after?
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Nitrogen Fixation
Becomes incorporated in amino acids / proteins. |
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What does the ecological relationship called commensalism imply?
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One species benefits while the other is not harmed or helped in any significant way.
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What is parasitism?
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Ecological relationship in which a parasite eats teh cell contents, tissues, or body fluids of its host; harmful!
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What is the ratio of bacteria cells to human cells?
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10 (bacteria) : 1 (human)
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What are some uses of bacteria?
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Snow making machine
Antibiotics Biofuels Food (yogurt, natto - Japanese delicacy) |
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What are the 6 shapes bacteria can come in? 3 main shapes?
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1) Coccus (sphere)
2) Rod (bacillus) 3) Coccobacillus (in between) 4) Vibrio (flexible) 5) Spirilum (slighly spiral) 6) Spirochetes (more spiral) 1) Round (cocci) 2) Rectangular (rod) 3) Spiral |
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What are the components of a bacteria?
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Cell Wall and Membranes
Cytoplasm and Periplasm Chromosomes and Plasmids Extracellular Polysaccharide Proteins - enzymes, flagella, pili |
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How many cell membranes do bacteria have?
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1 or 2 cell membranes
One = Gram POSITIVE (dark purple) Two = Gram NEGATIVE (red) (some have no cell membranes) |
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What do most bacterial cell walls contain?
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Peptidoglycan, a network of modified-sugar polymers cross-linked by short polypeptides (traps the crystal violet color for a Gram Stain)
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At what rate can bacteria multiply at?
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30 min, although most are at about 2 hours
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In what way are the number of bacterial cells expressed?
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Log scale
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What does the extracellular polysaccharide form around the bacteria? Why?
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Capsule which can help protect prokaryotes from attacks by the host's immune system.
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What is a thick-coated, resistant cell produced by a bacterial cell exposed to harsh conditions?
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Endospore
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What are three key features of prokaryotes' biology?
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1) Small
2) Reproduce by binary fission 3) Short generation times |
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How are fimbriae distinguished from pili?
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Fimbriae are smaller and used to attached to cell walls.
Pili (sex) engages in conjugation for transfer. |
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Although prokaryotic cells usually lack complex compartmentalization, what kind of specialization can they have?
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Specialized membranes that perform metabolic functions, i.e., respiratory membrane (aerobic), thylakoid membranes (photosynthesis).
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Prokaryotes have considerable genetic variation, what 3 factors contribute to this?
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1) Rapid Reproduction
2) Mutation 3) Genetic Recombination (conjugation, transformation, transduction) |
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Where does a phototroph get its energy from?
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Light
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Where does a chemotroph get its energy from?
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Chemicals
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Where do autotrophs get their carbon from?
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CO2
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Where do heterotrophs get their carbon from?
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Organic compounds
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What are the four major modes of nutrition?
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1) Photoautotroph (photosynthetic prokaryotes)
2) Chemoautotroph (very few prokaryotes) 3) Photoheterotroph (very few prokaryotes) 4) Chemoheterotroph (many prokaryotes and protists; fungi; animals; some plants) |
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What kind of nutrition do humans / animals engage in?
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Chemoheterotroph (carbon and energy from organic compounds)
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What is the role of biofilms? What are they?
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Metabolic cooperation (signaling molecules)
Surface-coating colonies - numerous bacterial species (plaque on teeth) |
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Crown Gall Disease occurs in trees and causes a large "gall" to form at the crown of the plant. What causes this? What is this an example of?
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Bacterial plasmid transfers DNA to plant cell, plant expresses the DNA as a "gall".
Transformation. |
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Are there bacteria that don't have a cell wall? What are they called?
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Yes: mycoplasmas - gram positive
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What are the major groups of bacteria?
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Proteobacteria
Chlamydieas Spirochetes Cyanobacteria Gram-Positive Bacteria (streptomyces and mycoplasmas) |
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What are the subgroups of proteobacteria?
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Alpha, Beta, Gamma, Delta, Epsilon
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If ____ were to disappear, the prospects for any other life surviving would be dim.
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Prokaryotes
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Which type of bacteria must live in other animal cells (obligate intracellular parasite), is the most common STD, and is the most common cause of blindness?
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Chlamydia
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What is the equivalent of mycoplasmas that attack plants called?
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Phytoplasmas
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What type of bacteria does this describe: obligate parasites, vertebrate hosts, smallest cells, requires sterols.
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Mycoplasma
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What is the smallest cell? Makes great model organisms...
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Mycolplasma
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Archaea are probably more closely related to?
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Eukarya
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What are the only similarities between bacteria and archaea?
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Both are prokaryotes that have no nuclear envelope or membrane-enclosed organelles; do have circular chromosomes.
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What character is unique to the domain archaea? What are these kinds of cells called?
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Ability for some species to grow at temp. above 100*C, thermophiles.
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What are halophiles able to do? Which domain are they in?
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Able to live in highly salty environments. Archaea.
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What are methanogens able to do? Which domain are they in?
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Use CO2 to oxidize H2, releasing methane as a waste product (poisoned by O2). Archaea.
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The protist kingdom is no longer used, yet the term is still used, why?
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Refer to eukaryotes that are neither plants, animals, or fungi.
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Who has a flagellum that operates via a molecular "motor"?
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Prokaryotes
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What can be said about the flagellum of prokaryotes and protists?
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They are analogous structures. Different in origin.
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Are flagella common in prokaryotes and protists?
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Over half do have a flagellum for each category.
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What is characteristic of Diplomonads (Excavata, Protist)?
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Modified mitochondrias
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What is characteristic of Parabasalids (Excavata, Protist)? What is the most well-known parabasalid? What does it do?
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Modified mitochondrias; Trichomonas viginalis - infects the vagina and urethra of males by feeding on vaginal lining.
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Trypanosoma is what kind of protist? What does it do? What is characteristic of this kind of protist?
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Kinetoplastid (Excavata)
Causes sleeping sickness. Massive mitochondria w/ a mass of DNA called a kinetoplast. |
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Which kind of protists have hairy flagellum? What does this category break down into (4)?
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Stramenopiles
-- Diatoms -- Golden Algae -- Brown Algae (seaweed) -- Oomycetes |
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What are the water molds, "fungal-like protists"? What do they produce?
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Oomycetes which produce oospores.
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What is the most famous ecological impact that oomycetes had?
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Potato Famine
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How did the potatoes of Ireland get infected?
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Via sporangia.
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What is the source of potato seed for potato growers?
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Specialized growers produce potato tubers (potato we eat) that are certified as disease free.
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Rotton, infected potatoes get put into a pile called what?
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Cull pile
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Protists have which kind of phylogenetic tree?
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Polyphyletic
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What is the sister group to stramenopiles?
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Alveolata
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What is characteristic of alveolates?
What are the subgroups (3)? |
Protists with membrane-bounded sacs (alveoli).
-- Dinoflagellates -- Apicomplexans -- Ciliates |
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Dinoflagellates are what kind of protists? What is another name for them?
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Alveolata
Phytoplankton |
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What kind of protists are parasites of animals and cause serious human diseases?
- What is one of the most prevalent examples of disease that it causes? - Example in Milwaukee? - Example spread in cats/rodents? |
Apicomplexans
- Malaria (plasmodium - transmitted through insects in sporozoites - merozoites) - Cryptosporidium (related to contaminated water in wells) - Toxoplasmosis (half of people in world have antibodies of this) |
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What is a potential problem with Toxoplasmosis (a disease caused by apicomplexans)? Where does this protist reproduction occur? How can you obtain it?
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If pregnant woman first gets disease while pregnant, the disease can cross placental barrier and affect fetus.
Reproduces in cats. Half of infections from not cooking meat well (or cats fecal matter). |
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What are plants (not protists) most closely related to?
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Green algae (protists)
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What are things are in the same clade as plants?
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Green algae and Red algae
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The unikonts (clade of protists) include what two categories and two major kingdoms?
What is characteristic of unikonts? |
1) Amoebozoans
2) Opisthokonts (Fungi & Animals) -- Single posterior flagellum |
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What is characteristic of amoeba?
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Engulf food by phagocytosis.
Somewhat related to animals (and fungi) |
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Why are fungi so important?
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Without fungi, there might not be plants.
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Fungi have cell walls made of what?
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Chitin
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What is the structure of the cells of fungi called? (2 kinds)
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Network of filaments called hyphae.
1) Septate hypha 2) Coenocytic hypha |
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What is a mass of hyphae called?
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Mycelium
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How are different kinds of fungi categorized?
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By their reproductive structures which produce spores
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What differentiates septate hypha from coenocytic hypha?
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Septate hypha are divided into cells by septa (w/ pores that allow flow of cell components).
Coenocytic hypha lack septa; continuous cytoplasmic mass w/ many nuclei (repeated division of nuclei w/o cytokinesis). |
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How do fungi obtain their nutrients?
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Either by releasing enzymes to environment which breakdown food for them to absorb, OR
Release haustoria (specialized hyphae) which act like straws and extract nutrients from hosts. |
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What are fungi that partake in a mutually beneficial relationship w/ plant roots called?
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Mycorrhizae
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What three crucial roles do fungi play in ecological interaction?
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Decomposers
Mutualists Parasites |
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How do fungi reproduce? (2)
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Asexually: spores
Sexually: plasmogamy - karyogamy - meiosis - germination |
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In fungal sexual reproduction, what is the fusion of cytoplasm? What does this produce?
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Plasmogamy - heterokaryotic cell (unfused nuclei from different parents: n + n)
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In fungal sexual reproduction, what is the stage that fuses the heterokaryotic nuclei? What does this produce?
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Karyogamy - diploid (2n) zygote
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In fungal sexual reproduction, what does meiosis produce? Where do they go from there?
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Takes zygote (2n) transforms to spores (n) which then go through germination.
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What is the alternative to producing spores in fungal sexual reproduction?
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Budding (as seen in yeasts)
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What are the five classes of fungi?
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1) Chytrids
2) Zygomycetes 3) Glomeromycetes 4) Ascomycetes ** 5) Basidiomycetes ** ** Most prevalent |
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What are the only fungi with motile spores (flagellum)? What does this class produce?
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Chytrids (produce zoospores)
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In zygomycetes, the mycelia can reproduce asexually by forming what?
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Sporangia full of spores
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Which kind of fungus grows on bread?
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Rhizopus (zygomycetes)
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What is the sexual reproductive cycle like for zygomycetes? What kind of cells do they have?
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Spores grow into mycelia (+ and -)
Plasmogamy (haploid, n --> heterokaryotic, n + n) (produces zygosporangium) Karyogamy (diploid, 2n) Meiosis (haploid, n) (zygospore germinates into sporangium) -- Coenocytic hypha |
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What kind of fungi form arbuscular mycorrhizae w/ plant roots? What is this an example of?
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Glomeromycetes - Mutualism
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Which kind of fungi are called "sac fungi"?
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Ascomycetes
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What are the edible ascomycetes that are kind of a delicacy?
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Morels
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What is characteristic of ascomycetes (fungi) during their sexual reproduction cycle?
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Production of sexual spores in saclike ascus (made of ascospores) (septa hyphae)
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While most fungi spend most of their time in the haploid (n) stage, which kind of fungi spend most time in the dikaryotic (n+n) stage?
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Basidiomycetes
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What are these common fungi classified as: mushrooms, puffballs, and shelf fungi?
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Basidiomycetes
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Which are the "sac fungi"?
Which are the "club fungi"? |
Sac = ascomycetes
Club = basidiomycetes |
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What are the majority of plant diseases caused by?
What are the majority of human diseases caused by? |
Fungi (pathogens) (fungi)
Bacteria and viruses (humans) |
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Symbiotic pairing of fungus and green algae produces what?
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Lichen
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What is one of the biggest contributions of fungi to humans?
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Some fungi produce antibiotics: penicillin.
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What do aflotoxins cause? What can they be found in?
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Liver cancer
Peanuts |
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What group of animals does not have true tissues?
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Sponges / Porifera
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What are the two distinctions of symmetry amongst animals?
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Radial --> Cnidarians (anenome, hydra, jellyfish)
Bilateral |
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Cnidarians have how many layers of tissues?
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2 - Ectoderm and Endoderm
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Bilateral symmetry has what characteristics?
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Two axes of orientation: front (anterior) to back (posterior), top (dorsal) to bottom (ventral).
Allows for a head/brain (cephalization) |
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What is a coelom?
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Cavity enclosed by mesoderm.
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What is an animal that does not have a body cavity?
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Acoelomate.
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What is an animal that has a body cavity in between the endoderm and mesoderm?
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Pseudocoelomate.
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What is the early embryonic development in animals?
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Zygote --> Cleavage --> Blastula (contains a blastocoel = empty cavity)
--> Gastrulation (forms endoderm/ectoderm and blastopore) |
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What is the cavity in side of a blastula formed after cleavage of the zygote?
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Blastocoel
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What are the three characteristics of a protostome, regarding (1) cleavage, (2) coelom formation, and (3) fate of the blastopore?
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(1) cleavage - spiral/diagonol and determinate
(2) coelom formation - solid masses of mesoderm split and form coelom (3) mouth develops from blastopore |
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What are the three characteristics of a deuterostome, regarding (1) cleavage, (2) coelom formation, and (3) fate of the blastopore?
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(1) cleavage - radial/perpindicular and indeterminate
(2) coelom formation - folds of archentron form coelom (3) anus develops from blastopore |
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What does indeterminate cleavage mean?
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Each cell in the early stages of cleavage retains the capacity to develop into a complete embryo.
(makes identical twins and stem cells possible) |
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Bilateral animals can be split up into what two categories (based on morphological characteristics)?
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Deuterostomes (includes chordates...) and Protostomes
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In the molecular phylogenetic tree of animals, what are the "protostomes" broken down into?
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Locotrophophores and Ecdysozoans (arthropods and nematodes)
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What is the act of shedding the outer skeleton called?
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Ecdysis
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What are the two characteristics of lophotrochophores?
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Lophophore - like a crown of tentacles that functions in feeding
Trocophore - distinct developmental stage - larva |
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What group do mollusks, annelids, brachiopods, and platyhelminthes fall under?
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Lophotrochophores
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What are two characteristics of platyhelminthes? What are most of them known as?
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Flatworms
-- no coelom -- 3 tissues: ecto/endo/meso-derm |
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What subcategories can flatworms be broken down into? (3) (Which are free-living, which are parasitic?)
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Turbellarians - free-living
Tapeworms - parasitic Flukes - parasitic |
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Flukes (flatworms) have part of their life cycle in which other animal? What is this called?
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Snails - schistosomiasis
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What proportion of people in the world are affected by flatworms?
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1/3
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What type of body cavity do nematodes have?
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Pseudocoeloms
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Which kind of animal is the most abundant?
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Nematodes
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What other living things are nematodes associated with?
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Animals, Plants, pathogens of insects
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What do plant-feeding nematodes have structurally?
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A stylet.
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How do nematodes kill insects?
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Nematode carries bacteria into insect.
Bacteria kills insect. Nematode eats bacteria and multiplies. |
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Where do nematodes get their nutrition from?
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Other nematodes, animals, plants, fungi, or bacteria.
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River Blindness is caused by which kind of animal? How is it transmitted? What is its health significance?
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Nematodes in lymphatic system.
Transmitted by black flies. One of leading causes of blindness in Africa. Can also cause shock and death. |
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The human pathogen Ascaris Lumbricoldes is caused by which kind of animal? How big is it? How do we get it? What does it do? How many people does it affect?
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Nematode
Up to a foot long. Obtained from undercooked meat. Lives in small intestines and latches on and lays up to 200,000 eggs; causes anemia and may be in as many as 1.2 billion people |
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What is the nematode disease in humans that is spread through undercooked pork? What does it cause?
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Trichinella Spiralis
Cysts in muscles --> inflammation, shock, death, extremely painful |
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What is the significance of Caenorhavditis elegans?
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It is a model system; nematode.
First multicellular organism to have its genome sequenced. Useful in lab since it just lives on bacteria. |
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Which group has the greatest number of species in the universe?
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Insects
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What kind of organisms are insects? When did their ancestors first show up?
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Terrestrial
Ordovician |
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Why are insects so much smaller than they used to be?
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Concentration of Oxygen in the atmosphere has changed.
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Why are there more species of insects in the world / what adaptation led to their success?
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Flight - allows them to fill different niches
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Animals / vertebrates evolved flight how much longer after insects did?
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80-100 million years approximately
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What is it suspected that insects evolved their wings from?
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Gills - aquatic ancestors - evolved into wings when they became terrestrial beings
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How many times did insects evolve wings throughout history?
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One time, as opposed to vertebrates who evolved wings many times.
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What are angiosperms?
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Flowering plants (vast majority = 90% of all plants)
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What did insects co-evolve with?
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Angiosperms (flowers)
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Which characteristic in insects helps them dominate terrestrial habitats?
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Social (organization)
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According to the molecular data phylogenetic tree of animals, what two groups are deuterostomes? What distinguishes them?
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Echinodermata (starfish)
Chordata -- have a notochord |
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What is a notochord? Who has them?
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It is a flexible rod of tissue which consists of fluid-filled cells in a fibrous tissue. It gives notochords some structure.
Found in all chordates. In vertebrates related to skeletal vertebrae; in humans related to disks between vertebrae. |
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What are the four features common to all chordates?
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1) Notochord
2) Dorsal, hollow nerve cord 3) Muscular, post-anal tail 4) Pharyngeal slits or clefts |
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Which extant chordate has a notochord but no skeletal mineralized bones or head?
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Lancelet
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Which chordate has a head but no backbone?
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Hagfish
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What is the first group that has a notochord, head, and backbone, but no jaw?
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Lamprey
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What is the category for animals with jaws?
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Gnathostomes
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What is the order of evolved traits in deuterostomes?
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Notochord
Head Vertebral column Jaws / Mineralized Skeleton Legs Amniotic Egg Milk |
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What groups are included in the tetrapods?
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Amphibia
Reptilia (includes birds) Mammalia |
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What is the main difference between birds (reptiles) and dinosaurs (otherwise they are very similar)?
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Feathers
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An amniotic egg is characterized by four extra-embryonic membranes, what are they?
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1) Amnion - membrane which surrounds amniotic cavity; cushions embryo from shock
2) Yolk sac - membrane which surrounds the nutrients (yolk) 3) Allantois - membrane which surrounds the disposed waste 4) Chorion - membrane which allows for gas exchange w/ allantois membrane |
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What distinguishes mammals from others with an amniotic egg (reptiles)?
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Milk and hair
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What differentiates monotremes from all other mammals?
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Lays eggs
No nipples for milk - young suck milk from fur of mother |
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How are marsupials distinguished from other mammals?
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Young mothers - embryo completes development in pouch on mother.
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Anthropoids can be split into what two groups?
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Monkeys (new-world and old-world)
Apes (including humans) |
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What are the non-human apes?
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Gibbon
Orangutan Gorilla Chimpanzees and Bonobos |
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How are apes different from monkeys?
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Larger brain
More social Can live in trees or on the ground More flexible behavior No tail Opposable thumb All (except humans) have flexible/grasping toe and similar arm to leg ratio Forward-facing eyes |
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What is the closest relative to humans?
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Chimpanzees (and bonobos)
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When did apes diverge from Old World monkeys?
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20-25 mya
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When did the first hominins appear? What was it called?
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6.5 mya
Sahelanthropus tchadensis |
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What is the significance of the hominin Australopithecus afarensis?
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Only 1 m tall; 40% complete skeleton of this species named Lucy (~3.2 bya)
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Which hominin are homo sapiens a direct descendent of?
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Homo ergaster (~1.7 mya)
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When did Homo sapiens first come about?
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200,000 years ago
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What is the "Out of Africa Hypothesis"? Where is the most variation found?
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Homo sapiens evolved in Africa and migrated outwards in various ways. (Map used mitochondrial DNA because nuclear genome is very similar).
Most variation in Africa; founder effect takes select subset of genes to other places. |
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Is there biological evidence of races?
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No; race is a social construct.
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Did Neanderthals give rise to European humans?
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Europeans are in a clade with other living humans; separate from Neanderthals.
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When did large-scale adaptive radiation occur?
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After each of the five mass extinctions, when survivors became adapted to the many vacant ecological niches.
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If a male patrols a group of females to prevent other males from mating with them, potentially leading to competition / combat, this is an example of what?
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Intra-sexual selection.
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