Biol 101: LO17

allopatric speciation

population becomes geographically isolated

allopatric speciation example

pupfish, panama isthmus, porto santo rabbits

sympatric speciation

evolves within the same geographic region, change in ploidy in plants

sympatric speciation example

lake victoria chichlids

prezygotic barriers

prevent mating and/or fertilization

postzygotic barriers

prevent gene flow after fertilization has occured

temporal isolation

different times

habitat isolation

different habitats

behavioral isolation

different courtship behaviors

mechanical isolation

incompatible reproductive organs

gametic isolation

games that are incompatible due to chemical differences

hybrid inviability

embryos die during development

hybrid sterility

hybrids do not reproduce successfully

hybrid breakdown

offspring of F1 cannot reproduce beyond a few generations, have reduced fitness

preadaptation

structure an organism already possessed that becomes modified as it adapts to a new role

macroevolutionary pattern

adaptive radiation

adaptive radiation

many species form over a short period of time from a few ancestral species

macroevolutionary pattern

extinction

background extinction

continuous extinction, always occurring

mass extinction

larger number of species killed over a period of time, due to major environmental catastrophes