Mechanisms of Evolution

Vocabulary

adaptation

process or trait that improves an organism’s ability to survive or reproduce in a given environment

allele frequency

the proportion of available slots at a given locus that have a particular allele

bottleneck effect

a type of genetic drift caused by a sharp decrease in population size; the gene pool of the remaining population may not reflect that of the original population

evolution

when defined narrowly, a change in gene frequencies within a population from one generation to the next

fitness

the number of surviving offspring that an individual contributes to the next generation

founder effect

a type of genetic drift in which a few individuals start a new population; the gene pool of the new population may not reflect that of the original population

gene flow

change in the gene pool caused by individuals entering or leaving a population

gene pool

the total set of alleles of all individuals in a population

genetic drift

the process by which random events cause random fluctuations in gene frequencies; these changes are not related to fitness or adaptation

genetic variation

differences among segments of DNA (through which traits are inherited) within a population

genotype

the genetic makeup of an organism

genotype frequency

the proportion of individuals in a population that have a particular genotype

Hardy-Weinberg equilibrium

the state of a population in which allele and genotype frequencies do not change between generations because evolution is not occurring

intersexual selection

a form of natural selection where mate choice by one sex results in different rates of success in reproduction between individuals

intrasexual selection

a form of natural selection where competition among individuals of same sex results in different rates of success in reproduction

locus (plural, loci)

the physical location of a gene on a chromosome

mutation

a change in DNA sequence

natural selection

a mechanism of evolution in which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do

population

an interbreeding group of individuals of the same species

sexual selection

a form of natural selection that focuses on reproduction, results from difference in reproductive success between individuals