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75 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What was the early earth like, and how might the conditions have favored the evolution of the first life forms?
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The early earth had no C02 and no C03 (ozone). It was anaerobic. Four million years ago, as the early earth cooled water vapor condensed to form early oceans.
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Describe the Miller-Urey experiment and tell how it supported the idea that life evolved very soon after the earth formed.
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in 1953, Stanley Miller stimulated the early atmosphere in a flask. Electricity + Methane + Ammonia + Hydrogen + Water + Etc. Amino acids, simple sugars, nucleotides, and other small molecules that are precursors to monomers of macromolecules.
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About half a billion years after life began, a group called the cyanobacteria evolved a very useful ability. What was this ability, and how did it shape the environment of the earth to make it favorable for more complex life forms?
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•Cyanobacteria created photosynthesis.
• This made Oxygen greatly increase. •The ability of cyanobacteria to perform oxygenic photosynthesis is thought to have converted the early reducing atmosphere into an oxidizing one, which dramatically changed the composition of life forms on Earth by provoking an explosion of biodiversity and leading to the near-extinction of oxygen-intolerant organisms. *Chloroplasts in plants and eukaryotic algae have evolved from cyanobacteria via endosymbiosis. * An increase in the concentration of oxygen in air or water would increase the size to which an organism could grow without its tissues becoming starved of oxygen. |
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When did animals evolve?
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around 530 million years ago
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What is the “Cambrian explosion”?
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It is the seemingly rapid appearance of most major groups of complex animals around 530 million years ago, as evidenced by the fossil record. This was accompanied by a major diversification of other organisms, including animals,
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Why could the “explosion” occur when it did in the history of life on earth?
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•Large increase in oxygen allowed for aerobic respiration and thus the evolution of many complex organisms.
• calcium carbonate (CaCO3) was more abundant, and that is an important component in the shells of many organisms. Having shells and skeletons may have allowed animals to evolve larger sizes and/or more complexity |
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Describe the situation of the land masses of earth at the end of the Permian period.
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•Climate got very cool, lots of glacier formation, sea levels at lowest ever; the majority of marine life went extinct.
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permian= permiafrost = "ice age"
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By the end of the Cretaceous period, what had happened?
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•the continents separated and flowering plants, and their pollinators, really begin to diversify.
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Briefly describe the relatively recent global climatic changes that occurred during the Pleistocene.
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Fluctuations of climate and sea level have led to many changes in biodiversity. Many large terrestrial vertebrates went extinct during the last ice age (ended 8,000 years ago).
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What is the Endosymbiontic Theory?
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•concerns the origins of mitochondria and plastids (e.g. chloroplasts), which are organelles of eukaryotic cells.
•According to this theory, these organelles (mitochondria and plastids (e.g. chloroplasts)) originated as separate prokaryotic organisms which were taken inside the cell as endosymbionts. •Mitochondria developed from proteobacteria and chloroplasts from cyanobacteria |
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Define microevolution.
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Microevolution is any change in the frequency of alleles in a gene pool (population) from one generation to the next.
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Give the “broad-scale” definition of evolution.
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The broad-scale definition of evolution is evolution is “descent with modification” from a common ancestor, resulting in changes in the features of organisms across generations.
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Big- Snakes evolve Down Mountians
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How are they related?
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They are related because the processes which alter gene pools from one generation to the next are responsible for generating ALL BIOLOGICAL DIVERSITY, including traits, species, major groups of organisms, etc.
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What are some of the “practical” reasons for studying evolution? Be able to list the ones I mentioned in class, and briefly describe at least one of these.
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Understanding how to combat and prevent diseases, understand how to develop new pesticides, helps lead scientists to discovery, creates knowledge for how organisms respond to environmental change, understanding ourselves. The theory of evolution is one of the most powerful and useful theories in all of science. It can help us to form explanations for any biological phenomenon.
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Scientists like Linnaeus were called “natural theologians”. Explain this.
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In the 17th and 18th centuries scientists who studied nature in an attempt to better understand the nature and mind of the ultimate creator were called “natural theologians”.
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Before about the time of Lamarck, what was the prevailing belief about how new species arose?
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The idea of descent with modification was gaining ground, but no one had any idea how it happens. Lamark proposed the mechanism of inheritance of acquired characteristics: organisms grow traits based on their use, and are able to pass changed traits to offspring.
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After Darwin, what was the view?
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After Darwin the view was natural selection: the process by which favorable heritable traits become more common in successive generations of a population of reproducing organisms, and unfavorable heritable traits become less common, due to differential reproduction of genotypes.
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at least four people that helped to shape Darwin’s thinking on evolution. Be able to explain in detail how the thinking of at least one of these people influenced Darwin.
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Malthus, Lyell, Lamarck, and Linnaeus. Lyell, a geologist, believed that the earth was very old and that biblical ideas of creation and timing had to be wrong. He gradually began to accept evolution, but had some unusual ideas. He worked with Hutton to establish that physical and chemical processes worked slowly and constantly through millennia. Darwin carried his book on Geology aboard the Beagle with him.
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M L^3 .. slader
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What two conditions are required of populations in order for natural selection to occur? Be able to briefly explain each.
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Compitition and variation:
•Heritable variation exists within populations of organisms. •Organisms produce more offspring than can survive. •These offspring vary in their ability to survive and reproduce. •These conditions produce competition between organisms for survival and reproduction -Individuals with beneficial traits will tend to survive and reproduce more than individuals with less effective traits. Those traits are passed from parent to offspring. |
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What were the five major components (ideas) of Darwin’s theory of evolution? Be able to briefly explain some of them.
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- Evolution- Changes in organisms across generations.
-Common Descent- Effectively argued that all species diverged from common ancestors. -Gradualness- Natural selection takes a long time to change traits and create complex adaptations. - Evolution is a POPULATION LEVEL phenomenon -Natural Selection- This explains what CAUSES evolution. The insight explained how traits can become well adapted to their environment over time. |
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What are four means by which evolution can occur?
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•Mutation
•Gene Flow •Genetic Drift •Natural Selection |
My Grandma Finds Good Deeds Noble and Special
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Define natural selection.
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•Natural Selection is the favoring of some individuals over others due to the traits that they exhibit.
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Give four examples of different kinds of traits that natural selection can act on (hint:there are four kinds of traits that I described in the lecture).
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•Examples: peppered moth, Darwin’s finches, three spine stickleback, and the common mussel.
•The moth originally mostly peppered moth. It was thought to be camouflaged on lichen-covered trees then eaten by birds. Industrial revolution in England killed lichens and darkened tree trunks with soot. Rare black morph became more common. Since environmental cleanup, peppered form has become more common again. This story has shown to be more complex, and perhaps not quite true in all details |
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Define fitness.
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The contribution an individual (or genotype) makes to the gene pool of the next generation, relative to the contribution of other individuals.
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Discuss the formula – R = h2 * S
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•“R” is the response to the selection. Evolution occurs when there is a selection of something and a variation in a phenotype of a gene.
•“h2” is the heritability or the degree of genetic control of the trait. The response to selection is how much the population changes. •“S” is the strength of selection |
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What is convergent evolution?
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Convergent evolution describes the acquisition of the same biological trait in unrelated lineages. For example we see similarities in the flying squirrels of North America and the sugar gliders of Australia.
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common egrits always believe in unrequited love
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What is the difference between continuous and discrete phenotypic variation?
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•A discrete phenotypic trait exhibits only a few categories. The variation depends on the genetic control of the trait.
•Quantitative variation is when individuals of a population cannot be readily separated into a small number of distinct categories; we say that the variation is continuous. |
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Define sexual selection.
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•Sexual selection is natural selection for mating success.
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What are the two kinds of sexual selection? Could you give an example of each?
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•Intrasexual selection is competition among the same sex. For example, beetles and snakes often fight each other for a mate.(poor cricket)
•Intersexual selection requires mate choice. This is often due to the males color or behavior (ex: peacocks and spiders).(deer) |
cricket and the deer
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Why are females the choosier sex?
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•Females generally have fewer opportunities to mate, so must be more “careful” in their choices. The ladies “eyeball” the guys and pick the best.
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What is “honest advertising”?
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•Honest advertising is questioning whether selection is causing males to lie. Should selection also favor unhealthy males that lie, like the lion with the comb over?
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What can a poor male cricket do to “get some girls” if he is a lousy singer?
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Sly male crickets produce no chirp themselves, but poach females attracted to another cricket's call.
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Natural selection may be the most important cause of evolution, but it is not the only cause. What three other processes can cause evolution? Can you define them?
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•Genetic drift- Random (due entirely to chance) changes in allele frequency within a population across generations.
•Gene flow- the movement of alleles into or out of a population. •Mutation- a change in the nucleotide sequence of a stretch of DNA |
Good Dogs- Read Cartoons Frequently
Flow = movement mutation= change in DNA |
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What are the two forms of genetic drift?
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•Two mechanisms are a genetic “bottleneck” and the “founder effect”.
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Good Dogs- Bring Food
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How are they different?
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•In the “bottleneck” a larger population suddenly contracts to a small size, genetic drift can result in sudden and radical changes in allele frequency that occur independently of selection.
•In the “founder effect” a few individuals with a rare allele in the originating generation can produce a population that has allele frequencies that seem at odds with natural selection. |
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Why is genetic drift such a concern to conservation biologists?
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Is progressively more important as population size is reduced (i.e., causes greater changes in small populations)
• Can alter allele/genotype frequencies rapidly and dramatically • Can cause total loss of alleles, thus reducing overall genetic diversity • As a result, is important in conservation |
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Define gene flow.
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Gene flow is the movement of alleles into or out of a population (immigration and emigration).
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The amount of gene flow, and its effect on a species, depends critically upon how the species is distributed in space. Most species are broken up into two or more populations with varying levels of gene flow. What are the four general patterns of gene flow among populations?
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• A) Continent-island model
• B) Full island model • C) One-dimensional stepping stone model • D) Two-dimensional stepping stone model |
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How is gene flow in sockey salmon likely to be different from that in Hawaiian gobies?
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Sockey salmon follows the one-dimensional stepping stone model. The gene flow is linear; small steps in a line. The Hawiian gobies, on the other hand, follow the full island model. They exchange alleles with gobies of other populations.
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Imagine two species of small fish living in a set of headwater streams. How might gene flow be different in the two species even though they live in the same streams?
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A mobile species could maintain contact between headwater “patches”. A sedentary species might show very reduced gene flow.
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Why can’t evolution via natural selection produce perfect organisms?
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• Evolution is limited by historical constraints – why are there no four-legged birds?
• Adaptations are often compromises (remember the idea of trade-offs?) • Natural selection is not the only “player” in the game...drift (a chance phenomenon) also is important, as is mutation • Selection can only act on existing variation... what is in the population NOW. Alleles do not appear or disappear “on demand” |
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What is speciation?
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It is the process where a species diverges into two or more descendant species.
Speciation is the process by which biodiversity is generated. |
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How are the biological, phylogenetic, and evolutionary species concepts related?
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The evolutionary species concept combines the genealogical basis of the phylogenetic species concept with the genetic basis of the biological species concept.
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What is a species, according to the Biological Species Concept?
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A population, or group of populations, whose members have the potential to interbreed in nature, and if they do they produce viable, fertile offspring; they are unable to produce viable, fertile offspring if they mate with members of another species.
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What are the two main modes of speciation, and how are they different? Which is the one that generates biodiversity (more species than you started with)?
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The two main modes are allopatric and sympatric.
They are different because in allopatric speciation is separated geographically, restricting the gene flow between the subpopulations. In sympatric speciation geographical isolation is not needed at all. Allopatric speciation generates more biodiversity. |
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What is an adaptive radiation. Give an example of one.
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Adaptive radiation is a special kind of cladogenesis. It is an evolutionary process driven by mutation and natural selection.
An example of this would be Darwin’s finches; they developed from the same species and became adaptive to the kinds of seeds they were eating. |
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What is the difference between pre-zygotic and post-zygotic isolating mechanisms? Could you give one example of each?
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Pre-zygotic isolating mechanisms are factors which prevent individuals from mating. For example, dragon flies fit together perfectly to mate so if they are trying to mate with the wrong insect it does not work or “fit”.
Post-zygotic isolating mechanisms include genomic incompatibility, hybrid inviability or sterility. For example, a horse and a donkey can mate to create a mule, but that mule is sterile. |
pre = prevent
post= donkey |
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What is the “function” of isolating mechanisms?
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To maintain species boundaries and create stronger more fertile beings.
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Why is it incorrect to say that evolution is equivalent to atheism?
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It isn’t! Science in general and evolutionary theory specifically, is unable to address the question of the existence of a “supernatural” being who created” everything. Evolutionary theory does contradict some specific “claims” on historical events that are referred to in religious writings (e.g., the Judaeo-Christian Bible) Evolution is no more intrinsically atheistic than medicine! Your doctor would never say, for example, “We don’t need to do any tests, because your condition is due to a curse by God. You must repent to be cured.”
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Why is it important for scientists (including doctors [especially those involved in medical research]) to assume that some higher being is not involved in the day-to-day working of the natural world?
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We must assume that “God” is not involved in our day-to-day studies. Because we cannot know which (if any) areas “God” is involved with, we must he/she is involved in none until we find uncontestable proof to the contrary.
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How do shared, nested traits of organisms show that evolution has occurred?
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•Organisms share nested sets of traits, which supports common ancestry E.g., all vertebrates have backbones, all tetrapods have backbones and 4 limbs, all amniotes have backbones, 4 limbs and amnion, etc.
•Shared genes among very different groups see picture |
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How do the panda’s “thumb” and the human eye provide support for evolution instead of intelligent design?
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The panda has an opposable thumb which is believed to have been developed since the panda eats bamboo; the thumb helps to hold its food. The human eye has developed in complexity and gradation over time. Darwin proposed the idea when discussing natural selection.
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There are five lines of evidence that favor an evolutionary hypothesis over an intelligent design hypothesis. Can you name them (I ran out of time to cover the one that is exemplified by organisms common to South America, Australia, and Antarctica – the marsupials).
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1.Hox genes
•Meaning the developmental transformation of a body segment). •It was subsequently discovered that mammals possess four sets, or 'clusters', of Hox genes. As opposed to the single set controlling development in the fruit fly 2.Similar development patterns among species •Organisms with shared traits also share similar developmental pathways. •The more similar the organisms, the more similar is their development • Distantly-related groups share many features of early development, closely-related groups share features of both early and late development 3.Ecological Analogues •unrelated organisms in separate geographic regions that are morphologically and ecologically similar 4. Geographic distributions •Geographic distributions of organisms (and fossils) can often be explained by geological events • splitting and movement of continents •Formation of rivers, mountain ranges •Organisms on oceanic islands resemble organisms on nearest mainland •Ex. South American Organisms •S. America used to be connected to Antarctica and Australia An island continent for last ~90 million years • Connected with N. America in last 4 million years •Distribution of fossils and living organisms can be explained by this history 5.“errors of design” •Vestigial traits E.g., human appendix, hind limbs in pythons and whales •“Errors” of design – E.g., vertebrate retina, panda’s thumb, non-coding DNA, appearance of temporary structures during development |
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Three mechanisms that produce evolutionary change.
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natural selection, genetic drift, gene flow.
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Natural selection.
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favors genes that improve capacity for survival and reproduction.
usually predominates in large populations |
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Genetic drift.
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is random change in the frequency of alleles, caused by the random sampling of a generation's genes during reproduction
dominates in small populations. The dominance of genetic drift in small populations can even lead to the fixation of slightly deleterious mutations.[54] As a result, changing population size can dramatically influence the course of evolution |
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Gene flow.
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the transfer of genes within and between populations.
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Population bottlenecks.
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where the population shrinks temporarily and therefore loses genetic variation, result in a more uniform population.
Bottlenecks also result from alterations in gene flow such as decreased migration, expansions into new habitats, or population subdivision. |
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The central concept of natural selection is...
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the evolutionary fitness of an organism
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the evolutionary...
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evolutionary fitness of an organism is...
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This measures the organism's genetic contribution to the next generation.
However, this is not the same as the total number of offspring: instead fitness measures the proportion of subsequent generations that carry an organism's genes. Consequently, if an allele increases fitness more than the other alleles of that gene, then with each generation this allele will become more common within the population. These traits are said to be "selected for". Conversely, the lower fitness caused by having a less beneficial or deleterious allele results in this allele becoming rarer — they are "selected against". Importantly, the fitness of an allele is not a fixed characteristic, if the environment changes, previously neutral or harmful traits may become beneficial and previously beneficial traits become harmful. (peppered moth) |
(peppered moth)
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sexual selection is...
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special case of natural selection
selection for any trait that increases mating success by increasing the attractiveness of an organism to potential mates. ex. in male deer, even though big antlers, mating calls or bright colors attract preditors and decrease survival rates the survival disadvantage is balanced by a higher rate of mate-ability in males that show these sexually selective traits |
deer
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Genetic drift (in depth)
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is the change in allele frequency from one generation to the next that occurs because alleles in offspring are a random sample of those in the parents, as well as from the role that chance plays in determining whether a given individual will survive and reproduce.
alleles are subject to sampling error. As a result, when selective forces are absent or relatively weak, allele frequencies tend to "drift" upward or downward randomly. This drift halts when an allele eventually becomes fixed, either by disappearing from the population, or replacing the other alleles entirely. Genetic drift may therefore eliminate some alleles from a population due to chance alone. Even in the absence of selective forces, genetic drift can cause two separate populations which began with the same genetic structure to drift apart into two divergent populations with different sets of alleles The time for an allele to become fixed by genetic drift depends on population size, with fixation occurring more rapidly in smaller populations.[67] The precise measure of populations that is important here is called the effective population size, a theoretical number representing the number of breeding individuals that would exhibit the same observed degree of inbreeding. |
two separate populations which began with the same genetic structure...
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Gene flow
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is the exchange of genes between populations, which are usually of the same species.
Examples of gene flow within a species include the migration and then breeding of organisms. Gene transfer between species includes the formation of hybrid organisms and horizontal gene transfer. Migration into or out of a population can change allele frequencies, as well as introducing genetic variation into a population. Immigration may add new genetic material to the established gene pool of a population. Conversely, emigration may remove genetic material. As barriers to reproduction between two diverging populations are required for the populations to become new species, gene flow may slow this process by spreading genetic differences between the populations. Male lions leave the pride where they are born and take over a new pride to mate. This results in gene flow between prides |
male lions
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Migration (into and out of)
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Migration into or out of a population can change allele frequencies, as well as introducing genetic variation into a population.
Immigration may add new genetic material to the established gene pool of a population. Conversely, emigration may remove genetic material. |
im/emigration
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barriers to reproduction between two diverging populations are..
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required for the populations to become new species.
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required...
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emigration...
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may remove genetic material
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remove
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Immigration...
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may add new genetic material to the established gene pool of a population.
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add
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outcomes of evolution
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are sometimes divided into macroevolution and microevolution
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big/ small
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macroevolution vs. microevolution
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macroevolution, which is evolution that occurs at or above the level of species, such as extinction and speciation
microevolution, which is smaller evolutionary changes, such as adaptations, within a species or population. In general, macroevolution is regarded as the outcome of long periods of microevolution. Thus, the distinction between micro- and macroevolution is not a fundamental one - the difference is simply the time involved. However, in macroevolution, the traits of the entire species may be important. For instance, a large amount of variation among individuals allows a species to rapidly adapt to new habitats, lessening the chance of it going extinct, while a wide geographic range increases the chance of speciation, by making it more likely that part of the population will become isolated. In this sense, microevolution and macroevolution might involve selection at different levels - with microevolution acting on genes and organisms, versus macroevolutionary processes acting on entire species and affecting the rate of speciation and extinction |
macroevolution endangers species
microevolution adapts species |
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Adaptations...
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are structures or behaviors that enhance a specific function, causing organisms to become better at surviving
and reproducing. They are produced by a combination of the continuous production of small, random changes in traits, followed by natural selection of the variants best-suited for their environment. This process can cause either the gain of a new feature, or the loss of an ancestral feature. As adaptation occurs through the gradual modification of existing structures, structures with similar internal organization may have very different functions in related organisms. This is the result of a single ancestral structure being adapted to function in different ways. Panda's thumb-being formed into a false "thumb," indicate that an organism's evolutionary lineage can limit what adaptations are possible |
pandas thumb
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vestigial structures...
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During adaptation, some structures may lose their original function and become vestigial structures.
Such structures may have little or no function in a current species, yet have a clear function in ancestral species wisdom teeth |
wisdom teeth
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Speciation...
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is the process where a species diverges into two or more descendant species.
In sexually-reproducing organisms, speciation results from reproductive isolation followed by genealogical divergence allopatric speciation, which occurs in populations initially isolated geographically, such as by habitat fragmentation or migration. Selection under these conditions can produce very rapid changes in the appearance and behaviour of organisms. As selection and drift act independently on populations isolated from the rest of their species, separation may eventually produce organisms that cannot interbreed. sympatric speciation species diverge without geographic isolation or changes in habitat. This form is rare since even a small amount of gene flow may remove genetic differences between parts of a population. Generally, sympatric speciation in animals requires the evolution of both genetic differences and non-random mating, to allow reproductive isolation to evolve. |
2 importants kinds but 4 in total
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allopatric speciation...
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which occurs in populations initially isolated geographically, such as by habitat fragmentation or migration. Selection under these conditions can produce very rapid changes in the appearance and behaviour of organisms. As selection and drift act independently on populations isolated from the rest of their species, separation may eventually produce organisms that cannot interbreed.
Finches |
finches- geography
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sympatric speciation...
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species diverge without geographic isolation or changes in habitat. This form is rare since even a small amount of gene flow may remove genetic differences between parts of a population.
Generally, sympatric speciation in animals requires the evolution of both genetic differences and non-random mating, to allow reproductive isolation to evolve. |
rare..oppisite of allopatric
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common descent...
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All organisms on Earth are descended from a common ancestor or ancestral gene pool.
Current species are a stage in the process of evolution, with their diversity the product of a long series of speciation and extinction events. The common descent of organisms was first deduced from four simple facts about organisms: 1) First, they have geographic distributions that cannot be explained by local adaptation. 2)Second, the diversity of life is not a set of completely unique organisms, but organisms that share morphological similarities. 3) Third, vestigial traits with no clear purpose resemble functional ancestral traits, 4) that organisms can be classified using these similarities into a hierarchy of nested groups. |
4 reasons..
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