AP Bio Unit 7/8 (anjeline's version)

Homologous Structure

A feature in different species that share a common origin even if it has different functions

Vestigial Organs

Organs that have lost most of their original function via evolution but are still present

Embryological Homologies

Similarities in developmental stages of species that show a common ancestor

Molecular Homologies

Similarities in molecular structure that show a common ancestor

Genetic Drift

Variation in frequency of genotypes in a small population

Bottleneck Effect

A sharp reduction in population size that decreases genetic diversity

Density-dependent factors

Ecological influences that affect population size and growth in relation to population density

Density-independent factors

Ecological influences that affect population size regardless of density

Resource Partitioning

Division of limited resources by species to avoid competition in a niche

Invasive Species

A non-native organism whose introduction to an ecosystem causes harm

Keystone species

Species with a disproportionately large effect on its environment relative to its abundance

Anatomical Homologies

Similarities in structure of different species from a common ancestor

Divergent Evolution

The process by which interbreeding species diverged in 2+ evolutionary groups

Adaptive Radiation

The process of organisms diversifying from an ancestral species into a multitude of forms

Convergent Evolution

The process of individual organisms evolving different structures with the same function

Analogous Structures

Structures with the same/similar functions but not from the same evolutionary origin

Geographic Variation

Differences in traits of populations in the same species across different locations

Founder Effect

A new population founded by original founders carrying a fraction of the total generic variation of the parental pop.

Allopatric Speciation

New species arise due to geographic isolation

Sympatric Speciation

Evolution of a new species from an ancestral species within the same area

Punctuated Equilibrium

The idea that evolution is caused by periods of rapid speciation after years of little to no change

Gradualism

The idea that evolution occurs via slow and small changes over long periods of time

Carrying Capacity

The maximum population size a species can handle without degradation

Symbiosis

Two organisms living in close physical association, often to the advantage of both

Trophic Structure

The partitioning of biomass between different trophic levels in an ecosystem

Mechanical Isolation

Prevents 2 species from interbreeding due to physical incompatibilities

Gametic Isolation

Prevents the fusion of gametes and stops fertilization

Postzygotic Barriers

Reproductive mechanisms after fertilization that reduce fertility and gene flow

Population

Group of organisms of the same species that live in the same area and can interbreed

K-selected

Organisms that produce few offspring but focus on survival

r-selected

Organisms that produce many offspring in unstable environments

Artificial Selection (selective breeding)

The crossing of 2 members of the same species with similar traits

Reproductive Isolation

Prevents different species from interbreeding and producing fertile offspring

Prezygotic Barriers

Prevent mating/fertilization between species before the formation of a zygote

Habitat Isolation

2 species could interbreed but don't because they occupy different habitats in the same area

Behavioral Isolation

Differences in mating behaviors/signals prevent different species from breeding

Temporal Isolation

Differences in mating timing or something else prevent closely related species from interbreeding even in the same area.