reproductive barriers/changes

speciation

process by which new species arise

geographic isolation

when populations are separated by physical barriers such as mountains or rivers

reproductive barriers

include timing, behavior, and mechanical differences that prevent interbreeding

biological species concept

defines a species as a group that can breed and produce fertile offspring

macroevolution

large-scale evolutionary changes, such as the emergence of new taxonomic groups

adaptive radiation

the rapid evolution of many diverse species from a common ancestor, often in new environments

directional selection

favors individuals with traits at one extreme

stabilizing selection

favors average traits and reduces variation

disruptive selection

favors individuals with both extremes of a trait over intermediate traits

temporal isolation

species breed at different times that leads to speciation

behavioral isolation

different courtship rituals prevent mating

mechanical isolation

reproductive structures are incompatible

gametic isolation

sperm and egg cannot fuse even if mating occurs

gene flow

the movement of alleles from one population to another