Chapter 12: The Forces of Evolutionary Change - Natural Selection and the Hardy-Weinberg Principle ch5

Flashcards covering key definitions related to evolutionary change, natural selection, and the Hardy-Weinberg Principle.

Evolution

Changes in heritable traits from generation to generation.

Allele frequency

The proportion of a specific allele in a population, calculated as (# of copies of an allele) / (Total # of alleles for the same gene in the population).

Gene pool

The combination of all the genes (including alleles) present in a reproducing population or species.

Natural selection

The mechanism of evolution where the environment influences the survival and reproduction of individuals with features best suited to it.

Variation (natural selection condition)

The presence of different heritable traits among individuals in a population.

Heritability (natural selection condition)

Genetic variations that can be passed down from parents to their offspring.

Differential survival and reproduction

Individuals with traits that are more beneficial in their environment are more likely to survive and reproduce.

Adaptations

Heritable features that provide a selective advantage by improving an organism’s ability to survive and reproduce.

Fitness (evolutionary)

An organism’s genetic contribution to the next generation, representing reproductive success.

Directional selection

A mode of natural selection that favors one extreme phenotype over another.

Disruptive selection

A mode of natural selection that favors individuals at both extremes of the phenotypic range over intermediate phenotypes.

Stabilizing selection

A mode of natural selection that favors intermediate phenotypes and selects against extreme variations.

Hardy-Weinberg Equilibrium (HWE)

The unlikely situation (null hypothesis) in which allele frequencies do not change between generations, used to test for evolution.

Assumptions of Hardy-Weinberg Equilibrium

Conditions for allele frequencies to remain constant: no natural selection, no mutations, large population size, random mating, and no migration.

p (Hardy-Weinberg Principle)

The frequency of the dominant allele in a population.

q (Hardy-Weinberg Principle)

The frequency of the recessive allele in a population.

p^2 (Hardy-Weinberg Principle)

The frequency of homozygous dominant individuals in the next generation.

q^2 (Hardy-Weinberg Principle)

The frequency of homozygous recessive individuals in the next generation.

2pq (Hardy-Weinberg Principle)

The frequency of heterozygous individuals in the next generation.