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186 Cards in this Set

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What is biological evolution?
The change of biological organisms between generations through time. Specifically populations of interbreeding organisms between generations.
What did Carolus Linneaus contribute?
Named species based on morphology. (mid-1700's, 6000+ species)
What did James Usher contribute?
Dated earth based on bible. (1658, 4004 BC)
What did James Hutton contribute?
Erosion changes face of earth slowly over time. (1785)
What did Charles Lyell contribute?
Earth is very old, gradualism, uniformitarianism.
What did Thomas Malthus contribute?
Populations kept in check by limited resources and mortality.
What did John-Baptiste Lamarck contribute?
Species not fixed, transform into one another through internal force and acquired characters.
What is Charles Darwins theory of evolution?
Natural selection, acting over many generations gradually produces new adaptations and new species.
Natural selection can be defined as:
Differential reproductive success
What are the two definitions of adaptation:
1) The processes by which adaptive traits are aquired.
2) The traits that enhance the survival and reproductive success of the bearers.
Define micro-evolution:
Rapidly occuring evolutionary change (virus mutations).
Define macro-evolution:
long terms patterns of evolutionary change.
What is the law of superposition.
Young rocks are found above old rocks.
Carbon 14 is used to date what and why?
The C 12-14 ratio in the environment is constant. When an organism dies the 12-14 ratio decreases overtime as new C is not taken up. Thus used to date fossils.
How are sedemintary rocks dated?
Hard to date, use lava flow btw sediment layers and date with K or Ar 40.
The oldest crust is:
4.4 byr. old and contains zircon crystal to accurately date it.
When were the first signs of life and how do we known.
3.85 byr. from high C12/13 ratio in sedementary rocks in Isua, Greenland.
What are boundaries between eras based on?
Major differences in the fossil organisms contained in the layers.
What heats the mantel of the earth?
Radioactive decay of earths core.
What does plate movement affect?
Climate, sea level, distribution and evolution of organisms.
When did oxygen concentrations begin to rise and why?
2.5 byr, prokaryotes began to photosynthesize.
What organism created stromatolites and what are they?
Cyanobacteria, layers of film to protect organisms from uv light. Cells then move above layer when becomes thick.
What seems necessary for the evolution of larger cells and organisms?
Oxygen rich atmosphere.
When did oxygen concentrations become high enough for eukaryotic cells?
1,500 mya
When did oxygen concentrations become high enough for multicellular organisms?
750-700 mya
How old is the first actual fossil, what is it of?
3.5 byr. Cyanobacteria?
-O2 begins to enter atmosphere
2.5-2byr
Define life:
A system that can convert raw material from the environment into copies of itself.into copi
What are two ubiquitous features of life?
Structured cell to organize energy for growth and reproduction, DNA.
The oldest life we think?
3.8 byr
First single-celled life forms with true nucleus.
1.5 byr
When are first multicellular organims?
600 myr
During what parts of the Precambrian era were large areas of the earth covered with glaciers?
Carboniferous, Permian, and Quaternary
What is an evolutionary radiation?
Periods marked by dramatic increase in diversity.
What are the steps of fossilization?
Death, burial, compaction, replacement of bones by rock, erosion to reveal fossil.
What are the rock types and how are they formed?
Igneous – volcanic action
Sedimentary - compression of sedaments
Metamorphic - heating and compression of other rock types
What type of rock can be dated and what type of rock has fossils?
Dated – igneous
Fossils - sedimentary
How long due most species exist on earth for?
Fewer than 10 million years.
What types of organisms are best represented in the fossil record?
Marine animals w/ hard skeletions, vertebratesm insects and spiders (amber)
When did ediacaran animals arise and what are they?
600 myr., non-placed phylogenetically
What are small, shelly faunas and when did they arise?
544 myr., tiny tubes, spines, cones and plates that are unlike any modern groups.
What were the Cambrian continents?
Laurentia, Siberia, and Gondwanaland
When did atmospheric O2 levels reach nearly current levels?
The early Cambrian.
Where are the best Cambrian fossils found?
Canada and China.
What occurred at the end of the Cambrian period?
Mass extinction.
When was the Cambrian explosion?
540 myr.
What event occurred directly before the Cambrian explosion?
Ediacaran and Vendian faunas disappeard.
Why is the Cambrian explosion signifigant?
All known phylum developed. Since then only one has disappeared and only one has arisen.
What are possible evolutionary triggers of the Cambrian explosion?
Evolution of hard parts, evolution of Hox genes, muscle and eyes for predation, increasing O2 levels.
What is the one phyla missing from the Cambrian?
Bryozoans
What occured during the Ordivician period and when was it?
490-443 mya., the continents were mostly in the Southern hemisphere. Crazy evolutionary radiation of marine organisms. First fish. Ancestors of plants and club mosses colonized the land. Followed by glaciation, 75% of sea life died.
What occured during the Silurian period and when was it?
443-417 mya. Marine organisms rebound from Ordivician extinction. Tropical sea had no barriers - dispersal of organisms. First known tracheophytes appear on land.
What occured during the Devonian period and when was it?
417-354 mya. Continents drift northward. Rates of evolution accelerate esp for marine mammals. All major groups of fishes present at end of period. First gymnosperms appear. Early amphibians (crazy and big) and tetrapods. Once again 75% extinction of marine organisms at end.
What occured during the Carboniferous period and when was it?
354-290 mya. Large glaciers up high, swamp forests in tropics led to formation of coal. Huge snails, scorpions, centipeded adn insects abound. Land life proliferates. Reptiles evolve. Crinoids on sea floor.
What occured during the Permian period and when was it?
290-245 mya. Land mass Pangea (all together) Major volcanic action. Ash causes largest glaciers in earths history. Reptiles overtake amphibians. Bony fish in oceans, reptiles lead to mammals.
What occured at the end of the Permian?
Large meteor, O2 leaves deep ocean, CO2 and H2S release from ocean. 96% of all life goes extinct.
What occured during the Mesozoic period and when was it?
248 mya. Pangea separates, glaciers melt. Life proliferates again. Life on each continent became distinct.
What occured during the Triassic period and when was it?
248-206 mya. Vertabrates diversify, confiers and seed ferns become dominant trees. Frogs and turtles arise. Reptiles radiate to dinosaurs, reptiles and birds. Mass extinction of 65% at end.
What occured during the Jurassic period and when was it?
206-144 mya. Two large continents: Laurasia and Gondwana. Ray finned fishes begin to dominate ocean, salamanders and lizards appear. Flying reptiles. Dinosaur bipedal predators, quadrapedal herbivores. Mammals
What occured during the Cretaceous period and when was it?
144-65 mya. Gondwana breaks. Continuous ocean in tropics. Flowering plants, more types of small mammals. Mass extinction.
What occured during the Cenozoic period and when was it?
65 mya. Continents where they are now, except Australia attached to antartica. Radiation of mammals. Flowering plants dominate.
Specifically talk about the tertiary period of the Cenozoic.
65-1.8 mya. Australia goes north. Climate drier and cooler, grasslands spread, invertebrates as they are today, birds mammals and reptiles radiate a lot.
What are the two epochs of the quaternary period of the cenozoic. When is the quaternary period?
Two parts: Pleistocene and Holocene
1.8 mya - present
Discribe the pleistocene epoch.
Major climate fluctuation. Hominids evolve, yield homosapiens. Glaciers retreated from temperate latitudes 15,000 yrs ago.
What is thought to cause a species to stay evolutionarily static over long periods of time?
Lack of environmental selective pressures for change.
What is extinction?
Removal of new species.
What is the background exctinction rate for animal families?
3-4 per million years.
Explain r=b+i-d-e
Rate of pop. growth equals birth plus immigration minus death minus emigration.
Explain what types of organisms are likely to survive or become extinct.
Widespread and common things survive, narrowly spread rare things become extinct.
Factors increasing probability of extinction:
- fragmented ranges
- occupy fewer sites within a range
- have smaller population sizes
- at limit of environmental tolerance
Explain the relationship between the size of a species ranges and the boundaries btw them.
Large geographic ranges have smoother boundaries than small ranges w/ typically more fragmented boundaries.
What types of forces lead to background extinction.
Population fluctuation, volcanic eruption, climate fluctuation, floods, competition w/ immigrants, new preditors and competitors, etc.
What qualifies a mass extinction?
>50% of species die, sudden, broad taxanomic coverage, changes in surviviing biota
What are some causes of mass extinctions?
Ocean circulation, global climate change, sea level change, volcanos, meteors
How many major mass extinctions?
5
When were the 5 mass extinctions?
Late ordovician, late devonian, end-permean, end-triassic, and cretacious-tertiary
What are the features of the Ordovician mass extinction and when was it?
438 mya. Caused by climatic change and glaciation of Gondwana. Sea level regression, anoxia. Potential collection bias.
What are the features of the Late Devonian mass extinction and when was it?
375 myr. Global temperature and sea level decline, meteorite impact.
What are the features of the Permo-triassic mass extinction and when was it?
248 myr. 96% of all species. GREATEST Productivity decline, continental shelf area decline, asteroid impact, global warming and cooling, volcanism and anoxia.
What are the features of the end-triassic mass extinction and when was it?
206 myr. Aridity, sea level regression, impact and rifting
What are the features of the K-T boundary mass extinction and when was it?
65 myr. Loss of dinosaurs. meteorite - volcanic eruption - climate change
What are the features of the Late Pleistocene extinction and when was it?
10,000 ybp. Mostly large mammals, few birds, dramatic geographic range changes in plants, dramatic geographic range changes in marine fauna. Human hunting a catalyst.
What are some of the present exctinctions occuring?
-tropical systems like reefs
-shallow water
-planktonic forms
-large-bodied animals
What is hunting by humans and habitat destruction causing?
Possibly the most massive extinction ever.
What are species?
Actually or potentially interbreeding populations which are reproductively isolated from other groups.
What is speciation?
The process by which one species splits into two species. Requires segregation of the gene pool.
Describe allopatric speciation.
Geographic separation and then independent evolution of species resulting in two non-interbreeding groups.
What is the founder affect?
A small group of founding individuals for a new species contain a subsample of the gene pool of the parent population.
What is a ring species?
A species where slightly variant groups can each interbreed, but the most divergent groups cannot.
How do isolation of members of a speices occur?
By vicariance (splitting), dispersal, distance
What is sympatric speciation?
A partition of a gene pool that occurs without physical separation.
What is the most common means of sympatric speciation?
Polyploidy
What is autopolyploidy?
chromosome duplication in a single species
What is allopolyploidy?
the combining of chromosomes from two different species
Discribe autopolyploidy:
The accidental production of tetraploid cells create plants that cannot produce fertile offspring with diploid plants. Genetic isolation occurs quickly.Di
Discribe allopolyploidy:
Arises when closely related species hybridize. Usually fertile because chromosomes have closely related partners.
What are the 5 prezygotic reproductive barriers?
- spatial isolation
- temporal isolation (diff. mating periods)
- mechanical isolation (reproductive organs diff)
- gametic isolation - gametes incompatable
- behavioral isolation
What are some examples of reproductive isolating mechanisms:
- Different mating songs btw species
- plant species using diff polinators
What are the 3 postzygotic reproductive barriers?
- hybrid zygote abnormality
- hybrid infertility
- low hybrid viability
What is reinforcement?
Poor survival of hybrid offspring reinforces the process of speciation.
Discribe a hybrid zone:
Formerly isolated populations interbreed in a specific region before speciation is complete.
What are the 3 possible outcomes a hybrid zone?
- offspring are succesful and spread through both populations and no new species result
- offspring are less successful and complete separation may occur as prezygotic barriers strengthen
- a narrow hybrid zone may persist if reinforcement does not occur
How does species richness affect speciation rates?
The more species there are, the more opportunities there are to make new species.
How do dipersal rates affect speciation rates?
The more members of a species are able to disperse, the faster new species will be formed.
How does ecological specialization affect speciation rates?
Species restricted to habitat types that are patchy in distribution are more likely to diverge than those in continuous habitats.
How do population bottlenecks affect speciation rates?
When extreme reductions in population size occur, new adaptations often result.
How does pollination mechanism affect speciation rates?
Animal pollinated plants have increased speciation rates.
How does sexual selection affect speciation rates?
Animals with complex sexual selection behavior result in rapid reinforcement of reproductive isolation btw species.
How does environmental change affect speciation rates?
Climate change can fragment formerly united habitats.
What geographical form encourages evolutionary radiations?
Isolated island environments with little competition from existing life.
Define systematics:
The scientific study of the diversity of organisms that reveals the evolutionary relationship between them.
Define taxonomy:
A subdivision of systematics that is the theory and practice of classifying organisms.
Define phylogeny:
A hypothesis that describes the the history of decent of a group of organisms from their common ancenstor.
What is cladogenesis:
Is split in the phylogenetic tree resulting in two new species.
What are the node, stem and crown in a phylogenetic tree?
Just what they sound like.
Define ancestral traits:
Traits inherited from a common ancestor that are shared between species.
Define derived traits:
A trait that differs from the ancestral form.
What is a homologous feature?
Any feature (DNA, behavior, etc) shared by species descended from a common ancestor.
Define convergent evolution:
When a given trait evolves independently more than once due to similar selective pressures.
Define evolutionary reversal:
When a character reverts from a derived trait to the ancestral trait.
Define homoplastic traits:
Similar traits tha tare not derived from a common ancestor.
Discribe the phylogentic relationship between an out-group and an in-group:
An outgroup is closely related to the in-group (lineage of interest) but has branched off from the group below its base of the evolutionary tree. Ancestral traits are found in both groups.
What are some traits commonly used to construct phylogenetic trees?
Morphology, DNA, RNA, proteins
What is the parsimony principle?
That the simplest evolutionary paths are most probable. (fewest homoplasies)
What is a consensus tree?
The outcome of merging multiple trees of equal length that were based on different information.
In what order to the classes in the Linnean Classification system go?
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
What do the terms in the binomial nomenclature of the Linnean Classification system denote?
Genus, species
What does spp. and sp. denote:
spp- more that one species in a genus
sp - an unspecified species in a genus
Define taxon:
A group of species treated as a unit.
What is a monophyletic group?
A clade that contains ALL the descendants of a particular ancestor, and no others.
What is a polyphyletic taxon?
Contains members with more that one recent common ancestor.
What is a paraphyletic group?
Contains some, but not all of the descendants of a particular ancestor.
Define a grade:
A paraphyletic group that has undergone rapid evolutionary change and should thus remain classified as a paraphyletic group.
Does genotype necessarily determine phenotype?
No, the same genotype can produce different phenotypes in different environments. Diff. genotypes can also have same phenotype.
What is a medelian population?
A locally interbreeding group within a geographic population.
What is genetic structure?
The frequencies of different alleles at each locul adn the frequencies of different genotypes in a Mendelian population.
What are the 5 assumptions required for a population to be at Hardy-Weinberg equilibrium, and what does this mean?
- mating is random
- population size is very large
- there is no migration btw populations
- there is no mutation
- natural selection does not affect the allels under consideration

A pop. in which allele and genotype frequency are constant
What does the HW equil tell us?
Allele frequencies do not change btw generations unless an external force exerts a pressure on them.
What are the known evolutionary agents?
Mutation, gene flow, random genetic drift, nonrandom mating, natural selection
What is gene flow?
When individuals migrate to a new location and breed with the pop there.
What is genetic drift?
The loss of certain alleles from a population due to death of organisms.
What is the founder affect?
The reduced number of alleles when a few individuals colonize a new region.
What is non-random mating?
When individuals mate preferentially with others of the same of diff genotype. Also, self-fertilization.
What is stabilizing selection?
Preserves the characteristics of a population by favoring average individuals. (baby birth weight)
What is directional selection?
Selection preferring individuals the vary in one direction from the mean. (giraffe necks)
What is disruptive selection?
Individuals varying in either direction from the mean are favored. (large or small beaks in birds)
Define intrasexual selection and intersexual selection.
Intra - trait give competitive advantage to reach opposite sex
inter - trait makes more attractive to opposite sex
Define a polygynous species:
One male theoretically controls reproductive access to many females.
What is biodiversity?
All living things and the processes that sustain them.
What are the two components of measuring biodiversity?
Richness and abundance
What are the different levels at which we can examine biodiversity?
Genetic, population, species, genera (some have many species others few), phyla (diversity of body plans)
What set of derived traits to all animals share?
- similarities in small subunit ribosomal RNA
- similarities in Hox genes
- special cell-cell junctions
- a common set of extracellular matrix molecules including collagen
What are metazoans and how did they evolve?
Coordinated groups of cells that form animals. Cells became specialized for diff functions. These cells continued to further differentiate and improve communication with other cells.
What general traits characterize animals?
- multicellular
- heterotrophs, take in other organisms
- expend energy to aquire organic molecules
- must have circulatory systems that transport CO2 and O2
What adaptations spawned the diversification of animal species?
Development of the ability to capture and eat many types of food. The need to move in search of food favored sensory structures.
Define spherical, radial and bilateral symmetry.
Spherical - body parts radiate out from central point
Radial - one main axis around which body parts are arranged
Bilateral - one mirror plane
Define cephalization:
The presence of a head bearing sensory organs and central nervous tissue at the anterior end of the animal
What is a body cavity and what parameter does it define for the animal?
A body cavity is a fluid filled cavity that defines how the animal can move.
Define acoelomates:
Lack an enclosed body cavity. Space between gut and body wall is filled with cell called mesenchyme.
Define pseudochoelomates:
Have a pseudocoel; a fluid filled space in which organs are suspended.
Define coelomates:
Have a coelom that develops within the mesoderm. Lined with pretoneum and enclosed on both sides by muscles.
What are hydrostatic skeletons?
The fluid filled body cavities of simple organisms that yield structural support.
Describe Porifera:
- lineage leading to sponges
- Sessile
- body plan: aggregation of cells around canal system
- sexual or asexual reproduction
Describe Cnideria:
- next to split off from animal line
- gut w/ one entrance
- have structural molecules such as actin, collagen, and homeobox genes
- include sea pens, jellies, corals
Describe Cnideria life-cycle:
Two stages with same body plan:
- polyp - asexual, reproduce by budding
- medusae - produces eggs and sperm which are released into water
Describe Ctenophora:
- 3rd to split off
- comb jellies
- body plan similar to cnidarians with radial symmetry and feeding tentacles
- separate mouth and anus
- tentacles are sticky
Why do we believe all bilateral animals are monophyletic?
All bilateral symmetry in all animals controlled by homologous hox genes.
What are the 5 shared traits of all protostomes?
- central nervous system w/ anterior brain that surrounds entrance to intestinal track
- ventral nervous sustem wtih paired or fused longitudinal nerves
- free floating larvae w/ a food collection system consisting of compound cilia
- blastopore that becomes mouth
- soem w/ spiral cleavage
What are the shared traits of deuterosomes?
- dorsal nervous system
- larvae (if present) collect food w/ cells having single cilium
- blastopore that becomes anus
- radial cleavage
- internal skeleton
Describe platyhelminthes:
- flatworms
- bilaterally symmetrical, unsegmented, acoelomate animals
- lack organs for transporting O2 to internal tissue
- simple organs for excreting metabolic waste
- feed on living or dead animal tissue
- flat form allows each body cell to be near body surface
- most parasitic - digest material from host
Describe brachiopoda:
- marine lophophorates that resemble mollusks
- two shell halves are dorsal and ventral
- attach to solid surface w/ short flexible stock
- release gametes into water for fertilization
Describe annelida:
- segmented body cavity (precise movement)
- worms that live in marine, freshwater, and land
- each segment controlled by one ganglion
- lack external rigid protective surface
- thin body wall allows for gas exchange
Describe mollusca:
- snails to giant squid
- foot, mantle, viscera
- foot for locomotion and support for internal organs
- mantle fold of tissue that covers internal organs
- many species have radula, feeding structure
Describe the bivalve class of mollusks:
- hinged two part shell
- mostly sedentary
- reduced heads
- water in through siphon, food extracted from water
- water and gametes excreted through another opening
Describe the gastropod class of mollusks:
- mostly motile (using large foot to move)
- mostly species rich of the mollusks
- crawl or swim
- only terrestrial mollusks
Describe the cephalopods class of mollusks:
- modified excurrent siphon
- move rapidly through water
- first large shelled animals to move vertically in ocean
Describe arthropoda:
- trilobites
- rigid exoskeleton, jointed appendages for many functions
- came on land several times
- often have head, thorax, abdomen
What group is the likely ancestor of a deuterostomes?
The yunnanozoans.
- large mouth
- 6 gills
- segmented posterior body section
Describe echinodermata:
- calcified internal plates covered by thin layers of skin and some muscle (fused to form internal skeleton_
- water vascular system (gas exchange, locomotion, feeding)
- calcified hydrolic canals leading to tube feet
- larvae have bilateral symmetry, adults have pentaradial symmetry
Describe hemichordata:
- proboscis, collar, trunk
- proboscus can dig and stick nutrients
Describe chordata:
- bilateral symmetry
- pharyngeal slits
- dorsal, hollow nerve cord
- ventral heart
- tail that extends beyond anus
- notochord
What are the sub-phyla of chordata?
urochordata, cephalochordata, vertebrata
How do the vertebrates differ from early chordata?
The vertebrates have a jointed, dorsal vertebral column that replaced the notochord as their primary support
Describe the chordata body plan:
- rigid internal skeleton
- two pairs of appendages attached to the vertebral column
- anterior skull with large brain
- internal organs suspended in large cavity
- well - developed circulatory system, driven by ventral heart
What characteristics of evolution do deuterostomes and protostomes share?
- got food from soft marine sediments
- body compartmentalized
- planktonic larval stages
- colonized land, skeleton gave advantage to deut. (which returned to water several times)