21 terms

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the number of times an allele occurs in a gene pool compared with the number of alleles in that pool for the same gene
allele frequency
form of reproduction isolation in which two populations develop differences in courtship rituals or other behaviors that prevent them from breeding
behavioral isolation
a change in allele frequency following a dramatic reduction in the size of a population
bottleneck effect
form of natural selection when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve
directional 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
disruptive selection
change in allele frequencies as a result of migration of a small subgroup of a population
founder effect
all the genes, including all the different alleles for each gene, that are present in a population at any one time
gene pool
random change in allele frequency caused by a series of change occurrences that cause an allele to become more or less common in a population
genetic drift
situation in which allele frequencies in a population remain the same
genetic equilibrium
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
geographic isolation
principle that states that allele frequencies in a population remain constant unless one or more factors cause those frequencies to change
Hardy-Weinberg principle
method used by researchers that uses mutation rates in DNA to estimate the length of time that two species have been evolving independently
molecular clock
trait controlled by two or more genes
polygenic trait
number of times that an allele occurs in e gene pool compared with the number of times other alleles for the same gene
relative frequency
separation of a species or population so that they no longer interbreed and evolve into two separate species
reproductive isolation
when individuals select mates based on heritable traits
sexual selection
trait controlled by one gene that has two alleles
single-gene trait
formation of a new species
speciation
group of similar organisms that can breed and produce fertile offspring
species
form of natural selection in which individuals near the center of distribution curve have higher fitness than individuals at either end of the curve
stabilizing selection
form of reproduction isolation in which two or more species reproduces at different times
temporal isolation