AP Bio Test

Sympatric speciation

New species forming in the same area due to reproductive

isolation (behavioral, temporal, or genetic).

Allopatric speciation

New species form because geographic barriers prevent gene flow.

Adaptive radiation

Rapid evolution of many species from a common ancestor to fill

ecological niches.

Convergent evolution

Independent evolution of similar traits in unrelated species due to

similar selective pressures.

Divergent evolution

Evolution of different traits in closely related species due to different

selective pressures.

Stabilizing selection

Favors intermediate phenotypes, reduces variation. Example: Human birth weight: average weight favored.

Directional selection:

Favors one extreme phenotype, shifts population trait distribution. Example: Peppered moths during industrialization.

Disruptive selection:

Favors both extreme phenotypes over intermediates. Example: Bird beaks: very small or very large beaks favored when seed sizes vary.

Homologous structure

Structures in different species with common ancestry, may have

different functions.

Analogous structure

Structures with similar function but independent evolutionary

origin

Vestigial structure

Structure that has lost most or all original function.

evolution

change in allele frequencies within a population over generations.

populations

evolution occurs in ___

natural selection

occurs when individuals with advantageous traits survive and reproduce more

successfully, leads to adaptations that improve survival and reproduction.

variation, heritability, competition for resources, and differential

reproductive success.

What four conditions must exist for natural selection to happen

fitness

an organism's ability to survive and reproduce in a specific environment, It is measured by reproductive success, or the number of viable offspring produced.

Adaptations

heritable traits that increase an organism's survival and reproduction.

Structural adaptations

adaptations that. involve physical traits such as camouflage or beak shape.

Physiological adaptations

adaptations that involve internal processes such as venom production.

Behavioral adaptations

adaptations that involve actions like migration or mating displays.

Directional selection

favors one extreme phenotype and shifts the population in one direction.

Stabilizing selection

favors intermediate phenotypes and reduces variation.

Disruptive selection

favors both extremes and selects against intermediate traits.

Genetic variation

necessary for natural selection to occur, includes mutation, crossing over, independent assortment, and random fertilization.

mutation

ultimate source of new genetic variation, a permanent change in DNA sequence, can be beneficial, neutral, or harmful, though most are neutral.

Gene Flow

the movement of alleles between populations due to migration, increase genetic variation and make populations genetically more similar.

Genetic Drift

a random change in allele frequencies due to chance, most significant in small populations and can reduce genetic diversity.

Bottleneck Effect

a drastic population reduction due to environmental disasters,

Founder Effect

small group splits off to establish a new population, carrying only partial genetic diversity. 

Hardy-Weinberg model

describes a population where evolution is not occurring, Allele frequencies remain constant if five conditions are met: no mutation, random mating, no

natural selection, very large population size, and no gene flow.

p² + 2pq + q² = 1.

equation for HW model

Sexual selection

favors traits that improve mating success.

Intrasexual selection

involves competition within one sex, often males.

Intersexual selection

involves mate choice, often females choosing specific traits.

Speciation

occurs when populations become reproductively isolated and evolve into separate

species.

Prezygotic barriers

prevent fertilization and include habitat, temporal, behavioral, mechanical, and

gametic isolation.

Postzygotic barriers

occur after fertilization and include reduced hybrid viability, reduced hybrid

fertility, and hybrid breakdown.

Artificial selection

when humans select organisms with desired traits to reproduce. Examples include dog breeding