Ch.16 Population_Genetics

BIOS 112 Fundamentals of Organismal Biology - Chapter 16 Population Genetics Study Guide

Evaluate the strength of supporting evidence

5 Conditions Necessary to Maintain Hardy-Weinberg Equilibrium:

  1. No mutation.

  2. No migration (gene flow).

  3. Large population size.

  4. Random mating.

  5. No natural selection.

Contribution to Microevolution:

  • Mutation: Introduces new alleles, affecting gene frequencies.

  • Gene Flow: Involves migration of individuals, introducing new alleles and altering allele frequencies.

  • Genetic Drift: Random fluctuations in allele frequencies, which can significantly impact small populations.

    • Bottleneck Effect: A dramatic reduction in population size reduces genetic diversity.

    • Founder Effect: When a small group establishes a new population, leading to reduced genetic variation.

  • Assortative Mating: Individuals choose mates based on particular traits, impacting allele frequencies.

  • Natural Selection: Different survival and reproduction rates of individuals with varying phenotypes lead to changes in allele frequencies.

Types of Natural Selection:

  • Stabilizing: Favors average phenotypes.

  • Directional: Favors one extreme phenotype.

  • Disruptive: Favors extreme phenotypes at both ends.

  • Balancing (Heterozygote Advantage): Maintains multiple phenotypes in a population.

Types of Sexual Selection:

  1. Female Choice: Females select mates based on specific traits.

    • Good Genes Hypothesis: Females prefer males with indicators of genetic fitness.

    • Runaway Hypothesis: Preference for certain male traits can become a feedback loop, enhancing those traits.

  2. Male Competition: Males compete for access to females.

    • Dominance Hierarchies: Social ranking that can influence mating success.

    • Sexual Dimorphism: Differences in traits between sexes that arise due to sexual selection.

Definitions:

  • Evolution: Change in allele frequencies in a population over time.

  • Microevolution: Small-scale changes in allele frequencies within a population.

  • Population: A group of individuals of the same species that can interbreed.

  • Population Genetics: The study of genetic variation within populations and how it changes over time.

  • Gene Pool: The total collection of alleles in a population.

  • Allele: Different forms of the same gene.

  • Allele Frequency: The proportion of a specific allele among all alleles present for a certain gene in a population.

  • Reproductive Isolation: Mechanisms that prevent different species from mating.

  • Fitness: The ability of an individual to survive and reproduce in its environment, contributing to the gene pool of subsequent generations.