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33 Cards in this Set
- Front
- Back
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evolution
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change in genetic makeup of a population over time
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direct evidence of evolutionary change
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fossils
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actual remains
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fossils that are unchanged animal parts, including teeth and bones
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petrification
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the process in which minerals replace the cells of an organism
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imprints
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fossils that are impressions left by an organism
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molds
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form in hollow spaces of rocks as the organism within decays
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casts
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formed by minerals deposited in molds
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homologous structures
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structures with the same basic anatomical features and evolutionary origins.
demonstrate similar evolutionary patterns |
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analogous structures
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structures with similar functions but may have different evolutionary origins and patterns of development. can't be used as a basis for classification
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how are the stages of development of an embryo evidence for evolution?
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embryos pass through stages that resemble its evolutionary history. Suggests a common ancestry.
example: human embryos go through a two-layer stage gastrula is similar to cnidarians, gill slits are present indicating common ancestry with fish, have a tail |
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how is comparative biochemistry evidence for evolution?
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the similarity of metabolic processes and chemical constituents in most lifeforms show a common ancestor.
Longer time since divergence of species means the two species will have more differences in biochemistry. |
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vestigial structures
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structures that appear useless but had some ancestral function
-human appendix is small and useless, but in herbivores it assists in the digestion of celluose -human tail -splints on the legs of horses are remnants of two side toes of Eohippus -pythons and whales have leg nubs |
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geographic barriers effect on evolution
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creates new species by isolating populations of the same species, after which the two populations can evolve adaptations specific to their environment, eventually genetic differences will reach the point where interbreeding between the groups is impossible, forming two distinct species
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phylogeny
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the evolutionary history of a group of organisms
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cladistics
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used to classify organisms based on phylogenic relationships
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clade
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subtree of a cladogram, members possess some kind of derived characteristic that distinguishes them from other clades
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Lamarckian Evolution
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new organs or changes in existing ones arose because of the needs of the organism. Amount of change was thought to be based on the use or disuse of the organ.
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Why was Lamarck's theory of evolution found false?
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Lamarck's theory was based on a wrong understanding of genetics. In it, traits acquired by the organism would be passed on to the next generation. This is false, as only changes in the DNA of sex cells can be inherited. Changes to the somatic cells cannot be inherited.
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Darwin's theory of natural selection
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Pressures in the environment select for the organism most fit to survive and reproduce.
-chance variations occur thanks to mutation and recombination -if the variation is "selected for" by the environment, that individual will be more likely to survive to reproductive age -survival of the fittest leads to an increase of those favorable genes in the gene pool |
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example of natural selection in action
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DDT resistant insects. The mutation for resistance existed before the introduction of DDT, but the insecticide selected for the survival of the DDT-resistant mutants.
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population
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all members of a species inhabiting a given location
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gene pool
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the sum of all the alleles for any given train the in the population
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gene frequency
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the decimal fraction representing the presence of an allele for all members of a population that have this particular gene locus
dominant allele - p recessive allele - q p+q=1 |
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Hardy-Weinberg Principle
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A gene pool is stable if:
1. population is very large. 2. no mutations affect the gene pool 3. mating between members of the population is random 4. no net migration of individuals into or out of the population 5. the genes in the population are equally successful at reproducing |
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Hardy-Weinberg equation
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p^2 + 2pg + q^2 = 1
p^2 = frequency of dominant homozygous 2pg = frequency of heterozygous q^2 = frequency of recessive homozygous |
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in nature, populations have unstable gene pools that are not in Hardy-Weinberg equilibrium due to these agents of microevolution:
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1. natural selection- more favorable genes will be more successful at reproducing
2. mutation- change allele frequencies 3. assortive mating- mates may not be chosen randomly 4.genetic drift- changes in gene pool due to chance 5. gene flow- migration of individuals between populations |
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speciation
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the evolution of new species
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deme
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small local population
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factors that lead to speciation
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genetic variation
changes in the environment migration to new environments adaptations to new environments natural selection isolation |
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adaptive radiation
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the emergence of a number of lineages from a single ancestral species
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convergent evolution
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unrelated groups developing similar characteristics when exposed to similar environments
ex- dolphin are mammals that are similar to fish |
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divergent evolution
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a single species is broken into groups that accumulate differences, leading to the formation of a new species
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parallel evolution
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development of a similar trait in related, but distinct, species descending from the same ancestor
example- marsupial wolves, mice, and anteaters of Australia developed the same characteristics as placental wolves, mice, and anteaters in response to similar environments |
