BIO2 MIDTERM: Microevolution and Macroevolution

Genetic Mutations

The raw material for evolutionary change, serving as a source of genetic variability.

Gene Flow

Movement of alleles between populations, which typically increases genetic diversity.

Non-random Mating

When individuals do not choose mates randomly, including assortative and disassortative mating.

Genetic Drift

Changes to allele frequency due to random chance, strongly affecting small populations.

Bottleneck Effect

A sharp reduction in population size leading to a loss of genetic variability.

Founder Effect

The reduced genetic diversity that results when a population is established by a small number of individuals.

Natural Selection

The process that adapts a population to its environment by favoring individuals with advantageous traits.

Directional Selection

Selection that favors individuals at one extreme of the phenotypic range.

Stabilizing Selection

Selection that favors intermediate phenotypes over extremes.

Disruptive Selection

Selection that favors extreme phenotypes over intermediate ones, leading to bimodal distribution.

Balancing Selection

A form of selection that maintains genetic diversity within a population.

Sexual Selection

A special case of natural selection that involves traits related to reproduction.

Macroevolution

Evolutionary changes that create new species and groups of species over long periods.

Biological Species Concept

Defines species based on reproductive isolation and the ability to produce viable offspring.

Prezygotic Mechanisms

Reproductive isolating mechanisms that prevent mating or fertilization between species.

Postzygotic Mechanisms

Reproductive isolating mechanisms that prevent hybrid offspring from developing or reproducing.

Allopatric Speciation

Speciation that occurs when populations are geographically isolated from one another.

Phenotype

The observable characteristics of an organism determined by its genotype and environment.

Allele

Different forms of a gene that can exist at a specific locus on a chromosome.