The Microevolutionary Process - Vocabulary Flashcards

Vocabulary-style flashcards covering key concepts from the lecture notes on the microevolutionary process.

microevolution

change in allele frequencies in a population over time

allele frequency

The proportion of a given allele among all alleles at a locus in a population.

genetic equilibrium

A state in which allele frequencies remain constant across generations and no evolution occurs.

Hardy-Weinberg equilibrium

A null model where allele and genotype frequencies remain constant in the absence of evolutionary forces; used to identify forces driving microevolution.

mutation

The process that introduces new genetic variation; the raw material of evolution; effects range from lethal to beneficial.

mutation rate

The frequency at which new mutations arise per generation.

lethal mutation

A mutation that causes death, preventing reproduction.

deleterious mutation

A mutation that reduces an organism’s fitness.

neutral mutation

A mutation with no effect on fitness.

beneficial mutation

A mutation that increases an organism’s fitness.

genetic drift

Random fluctuations in allele frequencies, especially in small populations; can reduce genetic variation and lead to fixation.

fixation

When the frequency of an allele becomes 1 in the population.

gene flow

The transfer of alleles between populations.

migration

Movement of individuals between populations, enabling gene flow.

bottleneck

A sharp, temporary reduction in population size that increases genetic drift and loss of genetic variation.

founder effect

When a new population is started by a small number of individuals, often with different allele frequencies from the original population.

source population

A population that donates migrants to other populations in a metapopulation.

sink population

A population that relies on immigration to persist or maintain numbers.

rescue effect

Immigration that reduces extinction risk for small populations by introducing new genetic variation.

drift and fitness (effects)

Genetic drift can lead to loss of variation and fixation of harmful alleles, increasing inbreeding and mortality.

directional selection

Natural selection that shifts allele frequencies in a single, consistent direction.

stabilizing selection

Natural selection that favors intermediate phenotypes and disfavors extremes.

disruptive selection

Natural selection that favors extreme phenotypes at both ends and disfavors intermediates.

random mating

Mating with no mate choice or preference, a condition of Hardy-Weinberg equilibrium.

no mutations (HW criterion)

One condition of Hardy-Weinberg: no new mutations enter the gene pool.

fully isolated (HW criterion)

HW condition: no gene flow with other populations.

allele has no fitness effect (HW criterion)

HW condition: alleles do not affect survival or reproduction.

conservation applications: wildlife corridors

Strategies to promote gene flow and genetic diversity by connecting habitats.

source-sink dynamics

A model where sources export individuals to sinks; sinks persist mainly due to immigration.