BIOL2040: Evolution - Lecture 6: Population Genetics II

These flashcards cover important vocabulary terms and concepts from the lecture on Population Genetics, emphasizing mechanisms of selection, mutation, and inbreeding.

Overdominance

A phenomenon where heterozygotes have a fitness advantage over homozygotes.

Heterozygote advantage

The condition where heterozygous individuals have a greater fitness than either homozygous type.

Sickle-cell anemia

A genetic disorder affecting red blood cells, causing them to be sickle-shaped and leading to various health issues.

Balanced polymorphism

A stable equilibrium in a population where two or more alleles persist due to selection.

Frequency-independent selection

Selection where the fitness of a phenotype does not depend on its frequency in the population.

Directional selection

A type of natural selection that favors one extreme phenotype over the others.

Underdominance

A scenario where heterozygotes have a lower fitness than homozygotes.

Polymorphism

The occurrence of two or more different alleles at a locus within a population.

Positive frequency-dependent selection

Selection where the fitness of a phenotype increases as it becomes more common.

Negative frequency-dependent selection

Selection where the fitness of a phenotype decreases as it becomes more common.

Gene flow

The transfer of alleles from one population to another.

Hardy-Weinberg equilibrium

A principle stating that allele and genotype frequencies will remain constant in a population from generation to generation in the absence of evolutionary influences.

Assortative mating

A non-random mating pattern where individuals with similar phenotypes mate more frequently.

Disassortative mating

A non-random mating pattern where individuals with different phenotypes mate more frequently.

Inbreeding depression

Reduced biological fitness in a given population due to inbreeding.

Inbreeding coefficient (F)

A measure of the likelihood that two alleles in an individual are identical by descent.

Mutation rate (µ)

The frequency at which a gene mutation occurs in a population.

Selection coefficient (s)

A measure of the relative fitness of a genotype as compared to the most fit genotype.

Familial Adenomatous Polyposis (FAP)

A genetic condition that causes cancer predisposition due to mutations in the APC gene.

Inbreeding coefficient

The proportion reduction in observed heterozygosity as a proportion of that expected under Hardy-Weinberg equilibrium.

Rovers and sitters

Different phenotypes in fruit flies, where rovers move more and sitters are sedentary.

Genetic drift

Random changes in allele frequencies in a population, often significant in small populations.

Migration-selection balance

The equilibrium state reached when the opposing forces of migration and selection stabilize allele frequencies.

Fixation index (Fst)

A measure of population differentiation due to genetic structure.

Negative frequency-dependent selection

Phenotypes favoured when their frequency in the population is low.

Sickle-shaped red blood cells

Red blood cells that are abnormally shaped due to sickle-cell disease, leading to health issues.

Fitness

The ability of an organism to survive and reproduce in its environment.