Evolution Review Part 2 Jan 2025 PDF

## Evolution Review - Part 2 ### 1. What is the Hardy Weinberg principle? An allelic frequency in a population does not change over successive generations. The population is at equilibrium. ### What are the five conditions that must be met in order to meet the Hardy Weinberg Principle? 1. No mutati...

## Evolution Review - Part 2 ### 1. What is the Hardy Weinberg principle? An allelic frequency in a population does not change over successive generations. The population is at equilibrium. ### What are the five conditions that must be met in order to meet the Hardy Weinberg Principle? 1. No mutation 2. No immigration or emigration 3. Population must be large 4. Random reproduction 5. No natural selection ### How does the Hardy Weinberg Principle prove the existence of evolution. It is virtually impossible to meet all 5 conditions. Allele frequencies do change and evolution occurs. ### In a class of individuals, 6 out of 20 have attached earlobes (ee). * **a) What is the frequency of the ee genotype?** 6 / 20 = 0.3 * **b) What is the frequency of the EE genotype?** p^2 = (0.45)^2 = 0.20 * **c) What is the frequency of the Ee genotype?** 2pq = 2(0.45)(0.55) = 0.495 * **d) What is the frequency of unattached earlobes?** 0.20 + 0.495 = 0.695 or 0.7 * **e) What is the frequency of the recessive allele?** q = √0.30 = 0.55 * **freg. of dominant allele: 1 - 0.55 = 0.45** ## 5. What are 5 ways that a gene pool can be altered? 1. Natural Selection 2. Immigration/Emigration 3. Genetic Drift (Bottleneck Effect/Founder Effect) 4. Non-random mating 5. Mutations ### 6. What is genetic drift? Change in the gene pool of a small population due to random chance. ### What is a population bottleneck? Give an example. Severe reduction in population of a species (near extinction) usually caused by a catastrophic event. * Example: Elephant seals - hunting reduced population to only 20 individuals in the 1890s. - rebuilding population lacks genetic variation blc. it is rebuilt from only a small gene pool. ### What is the founder effect? Give two examples. A small, founder group of individuals colonize a new area. Population in new area built from only the genes present in founding few (small gene pool). * **Example 1**: Afrikaner Population - lacks genetic diversity - has high freq. of Huntington's ### 9. Compare and contrast allopatric and speciation speciation. **Allopatric** - leads to reproductive isolation through physical geographic separation of individuals. The populations are separated and then diverge into separate species. **Sympatric** - leads to reproductive isolation subjected to different pressures. The population changes in their habitat and niche due to those pressures making them to diverge into separate species. ### 10. Give an example of geographic isolation. A physical barrier prevents gene flow (prevents mating between certain individuals) because they are physically separated. * Examples: mountains, canyons, glaciers, rising sea levels ### 11. What is reproductive isolation? Give four ways in which it occurs. When individuals can no longer offspring interbred to produce viable offspring. 1. Geographic Isolation 2. Niche differentiation 3. Altered behavior 4. Altered physiology ### 12. What is the difference between convergent and divergent evolution? **Convergent** - different organisms that live in similar habitat or environmental conditions, give rise to a number of similar, yet non-homologous structures. They have adapted to similar conditions. **Divergent** - ancestral species gives rise to different homologous - same common ancestor, have diverged due to different environmental pressures. ### 13. What is the difference between homologous and analogous species? **Homologous** - structures are due to a common ancestor. Have diverged due to different environmental pressures. **Analogous** - similar function, evolved due to similar environmental pressures. ### 14. What is the difference between punctuated equilibrium and gradualism? * **Did not cover** ### 15. Explain the importance of genetic variation to evolution and to the survival of a species. Genetic variation is what natural selection acts upon. Individuals are better suited. Genetic variation in a population, in turn, allows a few individuals to be less suited and not survive, while also allows a population to evolve in response to environmental or situational changes. High genetic variation in a world provides protection. Individuals carrying the alleles that would make them more likely to survive are least a few individuals carrying the genetic variations succeed. A population with low genetic variation is vulnerable to changes and may be killed off as a result.