Speciation

exam 3

Speciation

slow process where one species splits into 2 or more

forms the bridge between micro and macro evolution

one gene pool becoming two separate/different gene pools

Morphological Species Concept

a species shares the same physical/visible traits (common anatomical structures)

Phylogenetic Species Concept

smallest cluster of individuals descending from a unique common ancestor

the traits in common differ from descendants of the same ancestor

Ecological Species Concept

a group of organisms that share a common lineage and fill a similar niche

emphasizes disruptive selection (but could classify organisms that interbreed as two different species)

Biological Species Concept

interbreeding organisms that produce fertile offspring are a species (gene flow between populations)

excludes nonsexual reproducing species (parthenogenesis)

3 Steps of Speciation

1) geographic barriers or disruptive selection leads to reproductive isolation

2) reproductive isolation allows for unique genetic differences in each population

3) genetic differences enhance reproductive isolation

Allopatric Speciation

physical barriers present

has to be greater than an organisms capacity for movement

can result from founder event (distant colonization)

microevolution creates genetic divergence in populations once separated due to different selective pressures

Sympatric Speciation

no physical barrier present