the formation of new species as a result of evolution


the study of the structure and form of an organism

biological species concept

the concept that a species is a population of organisms that can interbreed but cannot breed with other populations

geographic isolation

the physical separation of populations due to geographic barriers that prevent interbreeding

allopatric speciation

happens when species arise as a result of geographic isolation; means "different homelands"

reproductive isolation

the inability of members of a population to successfully interbreed with members of another population of the same or a related species

prezygotic isolation

also called premating isolation, occurs before fertilization

postzygotic isolation

also called postmating isolation, occurs after fertilization

sympatric speciation

occurs when two subpopulations become reproductively isolated within the same geographic area; proposed by Darwin


the idea thta speciation ocurs at a regular, gradual rate

punctuated equilibrium

relative stability for long periods of time interspersed with much shorter periods during when many species become extinct and new species emerge; "punctuated" refers to sudden, rapid change and "equilibrium" refers to periods of little change

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

Voice Recording