Evolutionary Genetics: Selection, Assortative Mating, and Migration

Vocabulary flashcards covering topics from population genetics and evolutionary biology, including floral selection, dominant versus recessive deleterious alleles, positive and negative assortative mating, pheromones, and the impact of migration on Hardy-Weinberg equilibrium.

Coevolution (Flower-Pollinator Interaction)

The reciprocal evolutionary process where pollinators develop a preference for specific flower colors (e.g., hummingbirds preferring red, bees preferring white) based on nectar rewards, which in turn selects for those specific flower colors in the plant population.

Deleterious Recessive Alleles

Harmful alleles that persist in populations over long periods because they can hide phenotypically in asymptomatic heterozygous carriers ($2pq$), as seen in diseases like Tay Sachs disease, sickle cell anemia, cystic fibrosis, and SCIDs.

Unfavored Dominant Alleles

Deleterious alleles that cannot hide from natural selection because their negative phenotype is expressed in both homozygotes and heterozygotes ($2pq$), causing them to be eliminated from the population rapidly.

Assortative Mating

A system of non-random mating where an individual's mate choice is conditional on their own genotype or phenotype.

Positive Assortative Mating

A form of assortative mating where individuals preferentially choose mates with genotypes or phenotypes similar to their own ('like mates with like'), acting as a positive feedback mechanism that increases homozygosity ($p^2$ and $q^2$) and reduces heterozygotes ($2pq$).

Negative Assortative Mating

A mating pattern where individuals preferentially choose mates with genotypes or phenotypes different from their own ('opposites attract'), functioning to prevent inbreeding and maintain high heterozygosity.

Human T-Shirt Study

A study demonstrating negative assortative mating in humans, showing that individuals use pheromones to detect and prefer partners who have immune function genes different from their own to avoid inbreeding.

Pheromones

Chemical signals detected outside standard olfaction that convey genetic information about a potential mate, such as relatedness, immune profile, health, and disease state.

Population Substructure (Hardy-Weinberg Effect)

A scenario where pooling distinct subpopulations that are individually in Hardy-Weinberg equilibrium results in an apparent deficiency of heterozygotes ($2pq$) and an excess of homozygotes if their underlying allele frequencies differ.

$1\%$ Migration Threshold

The concept that a migration rate of just $1\%$ between two large populations is typically sufficient to maintain genetic connection and prevent complete genetic divergence.