Evolutionary Concepts: Selection and Speciation

Population

Group of individuals of the same species.

Genotypic Frequency

Proportion of different genotypes in a population.

Allele Frequency

Proportion of a specific allele in a population.

Disruptive Selection

Favors extreme phenotypes over intermediate ones.

Stabilizing Selection

Favors average phenotypes, reducing variation.

Directional Selection

Favors one extreme phenotype over others.

Microevolution

Small-scale evolutionary changes within a species.

Macroevolution

Large-scale evolutionary changes over long periods.

Species

Group capable of interbreeding and producing fertile offspring.

Reproductive Isolation

Barriers preventing species from interbreeding.

Prezygotic Barriers

Prevent mating or fertilization between species.

Postzygotic Barriers

Prevent hybrid zygotes from developing into viable adults.

Allopatric Speciation

Speciation due to geographical isolation.

Sympatric Speciation

Speciation occurring within overlapping populations.

Autopolyploidy

Chromosomal duplication within a single species.

Allopolyploidy

Hybridization between two species leading to polyploidy.

Adaptive Radiation

Rapid evolution of diversely adapted species from a common ancestor.

Founder Effect

Genetic drift occurring when a few individuals establish a new population.

Bottleneck Effect

Loss of genetic diversity due to a drastic reduction in population size.

Gene Flow

Movement of alleles between populations through migration.

Natural Selection

Process where individuals with advantageous traits reproduce more.

Sexual Selection

Natural selection based on mate choice and competition.

Sexual Dimorphism

Differences in appearance between males and females.

Heterozygote Advantage

Higher fitness of heterozygous individuals compared to homozygotes.

Punctuated Equilibrium

Evolution characterized by long periods of stasis interrupted by rapid change.

Gradualism

Slow, continuous evolution over long periods.

Hybrid Breakdown

Reduced fitness of subsequent generations of hybrids.