Population Genetics Lecture Notes

Flashcards covering key concepts in population genetics and evolutionary biology.

Population Genetics

The study of genetic variation within populations and how allele frequencies change over time.

Gene Pool

The total collection of alleles in a population.

Microevolution

Small scale evolution that occurs within a species over time.

Mutations

Changes in genotype that can create new phenotypes, impacting fitness and serving as the original source for genetic variation.

Genetic Drift

Random fluctuations in allele frequencies, especially in small populations, which can decrease genetic variation.

Founder Effect

When a small group breaks away from a larger population, carrying only a fraction of the original population's genetic diversity.

Bottleneck Effect

A sharp reduction in population size due to an event, leading to loss of genetic diversity.

Gene Flow

The transfer of alleles between populations due to migration.

Natural Selection

The process where individuals with traits better suited to their environment have a higher chance of survival and reproduction.

Directional Selection

A form of natural selection that favors one extreme phenotype, shifting allele frequencies in one direction.

Stabilizing Selection

Natural selection that favors the average phenotype and reduces variation.

Disruptive Selection

Natural selection that favors extreme phenotypes at both ends of the spectrum.

Sexual Selection

Natural selection based on the preference for certain traits in mates.

Speciation

The formation of new and distinct species as a result of reproductive isolation.

Allopatric Speciation

Speciation that occurs when populations are geographically isolated.

Sympatric Speciation

Speciation that occurs while populations live in the same geographic area but are reproductively isolated.

Adaptive Radiation

The evolution of organisms into separate species that occupy different ecological niches.

Punctuated Equilibrium

The model of evolution that proposes species experience long periods of stasis interrupted by rapid evolutionary changes.

Gradualism

The model of evolution that proposes slow, steady changes over time.

Prezygotic Barriers

Barriers that prevent mating or fertilization between species.

Postzygotic Barriers

Barriers that occur after fertilization, leading to hybrid inviability or infertility.

Mechanical Isolation

Structural differences in reproductive organs that prevent successful mating.

Gametic Isolation

A type of prezygotic barrier where the sperm and egg are incompatible.

Reduced Hybrid Viability

When hybrid offspring do not survive to maturity.

Hybrid Breakdown

When hybrids are viable but their subsequent generations are inviable or infertile.

Coevolution

The process by which one species evolves in response to the evolution of another species.

Mass Extinction

A large number of species going extinct over a short period of time due to major events.

Background Extinction

The natural process of species elimination that maintains the balance of ecosystems.