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Evolution
| Question | Answer |
|---|---|
| What is evolution? | Changes in allele frequencies in populations, species, or groups over time; driven by natural selection |
| What is microevolution? | Changes in allele frequencies that occur within a population |
| What is macroevolution? | Patterns of changes in groups of related species over broad periods of geologic time |
| What did Lamarck propose? | That body features acquired during one's lifetime (due to use/disuse) can be passed down to offspring — this is FALSE |
| What did Darwin-Wallace propose? | Natural selection ("survival of the fittest") |
| What is natural selection? | Changes in allele frequencies that lead to increased fitness ("survival of the fittest") |
| What is fitness? | The ability of an organism to survive and produce fertile offspring |
| What are the 3 requirements for natural selection? | 1) Heritable variation among individuals in the population 2) Competition: demand for resources exceeds available resources 3) Accumulation of favorable traits that promote increased fitness |
| What is stabilizing selection? | Selection that favors the intermediate phenotype and reduces variation; extremes are selected against |
| What is disruptive selection? | Selection that favors both extreme phenotypes over the intermediate; increases variation |
| What is directional selection? | Selection that favors one extreme phenotype, shifting the population in that direction over time |
| What is genetic equilibrium? | When allele frequencies remain constant from generation to generation; occurs when no evolution is taking place |
| What are the 5 requirements for genetic equilibrium (Hardy-Weinberg)? | 1) No mutations 2) No natural selection 3) No gene flow 4) Large population 5) Random mating |
| What is the Hardy-Weinberg equation? | p² + 2pq + q² = 1, and p + q = 1; where p = frequency of dominant allele, q = frequency of recessive allele, p² = homozygous dominant, 2pq = heterozygous, q² = homozygous recessive |
| What is genetic drift? | A random increase or decrease of an allele frequency in a population; includes the founder effect and bottleneck effect |
| What is gene flow? | The addition or removal of alleles from a population when individuals enter or leave |
| What are all the causes of changes in allele frequencies? | Genetic drift, gene flow, non-random mating, mutations, natural selection |
| What are the 4 sources of genetic variation? | 1) Mutation 2) Sexual reproduction (genetic recombination, independent assortment, random joining of gametes) 3) Balanced polymorphism/heterozygote advantage 4) Diploidy (recessive alleles stored in heterozygotes for later generations) |
| What is balanced polymorphism? | The maintenance of different phenotypes in a population; includes heterozygote advantage, where the heterozygote is more fit than either homozygous condition |
| What are homologous structures? | Body parts that resemble one another between different species descended from a common ancestor (e.g., bat vs. bird forelimbs) |
| What are analogous structures? | Body parts that resemble one another between different species that evolved independently, not from a common ancestor (e.g., bat vs. bee wings) |
| What is divergent evolution? | Formation of two or more species from a common ancestor that become increasingly different over time; the result of speciation (e.g., fox, wolf, and domestic dog) |
| What is convergent evolution? | Two unrelated species independently evolving similar traits due to adapting to similar environments; produces analogous traits (e.g., bat and bird wings) |
| What is parallel evolution? | Two related species developing similar adaptations after diverging from a common ancestor (e.g., mammoth and elephant) |
| What is coevolution? | Two or more species with a close ecological relationship evolving together in response to new adaptations in the other species (e.g., predator/prey relationships) |
| What is speciation? | The formation of a new species; begins when gene flow ceases between two sections of a population |
| What is a species? | A group of individuals capable of interbreeding |
| What is allopatric speciation? | Speciation that occurs when a population is divided by a geographic barrier |
| What is sympatric speciation? | Speciation that occurs without a geographic barrier (e.g., via polyploidy or habitat differentiation) |
| What are the 5 prezygotic barriers to reproduction? | 1) Habitat 2) Temporal — species reproduce at different seasons/times 3) Behavioral — species do not perform the correct courtship rituals 4) Mechanical — male/female genitalia are incompatible 5) Gametic — male/female gametes do not recognize each other |
| What are the 3 postzygotic barriers to reproduction? | 1) Hybrid inviability — offspring dies before reaching reproductive maturity 2) Hybrid sterility — offspring cannot reproduce 3) Hybrid breakdown — offspring have reduced viability or fertility |
Created by:
smurtab