Chapter 17: Evolution of Populations Flashcards
Allele frequency
Number of times that an allele occurs in a gene pool compared with the number of alleles in that pool for the same gene
Gene pool
all of the genes, including all the different alleles for each gene, that are present in a population at any one time
Single-gene trait
trait controlled by one gene that has two alleles
polygenic trait
trait controlled by two or more genes
Directional selection
Form of natural selection in which in which individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve
Stabilizing Selection
Form of natural selection in which individuals near the center of a distribution curve have higher fitness than individuals at either end of the curve
Disruptive Selection
Natural selection in which individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle of the curve
Genetic Drift
Random change in allele frequency caused by a series of chance occurrences that cause an allele to become more or less common in a population
Bottleneck effect
A change in allele frequency following a dramatic reduction in the size of a population
Founder effect
Change in allele frequencies as a result of the migration of a small subgroup of a population
Genetic equilibrium
Situation in which allele frequencies in a population remain the same
Hardy-Weinberg Principle
Principle that states that allele frequencies in a population remain constant unless one or more factors (non-random mating, small population, selection, mutations, and migrating)
Sexual Selection
When individuals select mates based on heritable traits
Species
group of similar organisms that can breed and produce fertile offspring
Speciation
Formation of a new species
Reproductive isolation
Separation of a species or population so that they no longer interbreed and evolve into two separate species
Behavioral isolation
Form of reproductive isolation in which two populations develop differences in courtship rituals or other behaviors that prevent them from breeding
geography isolation
Form of reproductive isolation in which two populations are separated by geographic barriers such as rivers, mountains, or bodies of water, leading to the formation of two separate subspecies
Temporal Isolation
Form of reproductive isolation in which two or more species reproduce at different times
Molecular Clock
Method used by researchers that uses mutation rates in DNA to estimate the length of time that two species have been evolving independently
