species

a group of individual organisms that interbreed and procure fertile, viable offspring.

hybrid

cross between two species

speciation

the formation of two species from one original species, occurs when 2 new populations must form from one original population who must evolve so that it becomes impossible for 2 members of the new population to breed.

allopatric speciation

involves geographic separation of populations from a parent species and subsequent evolution

sympatric speciation

speciation occurring within a parent species remaining in one location

dispersal

when a few members of a species move to a new geographical area, allopatric process.

vicariance

when a natural situation arises to physically divide organisms, allopatric process.

adaptive radiation

a population of one species disperses and finds a district niche or isolated habitat; multiple speciation events occur from a single species over time.

polyploidy

when a cell or organism has an extra set of chromosomes

autopolyploidy

multiple chromosomes from ones own species

allopolypoid

occurs when gametes from two different species combine

reproductive isolation

ability to interbreed

prezygotic barrier

a mechanism that blocks reproduction from taking place

postzygotic barrier

occurs after zygote formation. includes organisms that don't survive embryonic stage and ones born sterile.

temporal isolation

differences in breeding schedules, a form of reproductive isolation

habitat isolation

population of species move to new habitat and live in a place that no longer overlaps with the same species. creates new group that is reproductively and genetically independent

behavioral isolation

occurs when the presence or absence of a specific behavior prevents reproduction

gametic barrier

prezygotic barrier that works when difference in their gamete cells prevent fertilization from taking place

hybrid invariability

hybrid organisms that are not viable