Bio1151b Chapter 23 The Evolution of Populations
  1. Natural selection acts on individuals, but              evolve, based on genetic variations, the change in genetic makeup of a population over time is called                 .
  2. A             is a localized group of individuals that are capable of interbreeding and producing          offspring.
  3. As a population evolves, its         and           frequencies change. Such               change can be analyzed by comparing it to a non-evolving population.
  4. A non-evolving population reaches the                 equilibrium due to Mendelian              of alleles, under five idealized conditions:
    • Extremely        population size.
    • No gene       due to migration.
    • No            .
    •         mating.
    • No natural            .
  5. Mendelian inheritance preserves         frequencies in a population, resulting in constant          variation.
  6. At Hardy-Weinberg equilibrium, the distribution of 2          p and q in a population can be modeled by these equations:
    • The         frequencies are described by p + q = 1, where p is the dominant allele frequency and q is the recessive allele frequency.
    • The           frequencies are described by p2 + 2pq + q2 = 1.
  7. Mutation and sexual                produce the variation that makes evolution possible.
    • Genetic        in small populations result tends to         genetic variation. In very small populations the              effect can contribute to severe loss of genetic diversity.
    • Gene       from the movement of individuals or gametes between populations can affect allele frequencies and tends to         genetic differences between populations.
    •           is the basis for natural selection, and results in unequal reproduction of alleles.
    • Selection favors certain            by acting on the             of individuals.
      •              selection favors individuals at one end of the phenotypic range.
      •             selection favors individuals at both extremes of the phenotypic range.
      •              selection favors intermediate phenotypes.
    • Summary.
  8. Heterozygotes sometimes may possess greater          than homozygotes and preserve a recessive allele in a population due to               advantage.
  9. In many species          are choosy in selecting their mates, resulting in sexual             . This is called              selection, or       choice.
  10.              selection is the competition among males for access to mates, often at the peril of their own survival.