Bio 114; Unit 9 - Random Evolutionary Mechanics

Genetic drift

random change in allele frequency from one generation to another

allele fixation

a single allele is the only allele remaining in the population; smaller populations will reach allele fixation faster

Heterozygosity (H)

measures the probability of drawing 2 different alleles from the gene pool; also called gene diversity; always equals 1

Heterozygosity equation

H = 1-(p²-q²)

Habitat fragmentation

previously large, continuous habitat is broken into smaller unconnected pieces

Habitat loss

loss of land, reduced space

ecological corridors

between conservancies to maintain gene flow between populations

bottleneck effects

occur when an environmental/human catastrophe kills a large percent of the population; population size may rebound but genetic diversity is subset

Founder event

new, smaller population of “founders” break off from the original population

founder effect

occur if the new population has lower genetic diversity than original population

Gene flow

introducing or removing alleles from a population; change allele frequency

mutation

permanent, RANDOM change in the DNA sequence of an organism; ultimate source of ALL variation that evolution acts on