Species and Speciation Examples

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African cichlids in Lake Victoria include hundreds of closely related species. Many look similar morphologically but genetic analyses reveal distinct lineages.

How many independently evolving lineages exist within the lake?

Evolutionary Species Concept

Finches on the Galápagos Islands differ in beak size and shape depending on the food resources they exploit.

Do distinct niches correspond to distinct species boundaries in these finches?

Ecological Species Concept

Ensatina salamanders form a ring of populations around California’s Central Valley. Neighboring populations interbreed but southern populations do not interbreed where they meet.

Are the southern populations reproductively isolated when they come into contact?

Biological Species Concept

Mosquitoes in the Anopheles gambiae complex appear morphologically identical but contain several genetically distinct lineages.

What are the smallest genetically diagnosable evolutionary lineages relevant to disease transmission?

Phylogenetic Species Concept

Paleoanthropologists study fossils such as Homo erectus and Homo habilis and must often classify specimens using only anatomical features.

Do two fossil skulls represent the same species.

Morphological Species Concept

Rhagoletis pomonella flies historically used hawthorn fruit, but some populations now use apples. The two groups live in the same areas and look identical, but their hosts fruit at different times, affecting mating timing.

Are differences in mating timing reducing gene flow between apple and hawthorn populations?

Biological Species Concept

Polar bears and brown bears differ in morphology, habitat, and diet but can hybridize where their ranges overlap

Do polar bears represent a lineage adapted to a distinct ecological niche compared with brown bears?

Ecological Species Concept

Two tree frog populations look identical but produce different mating calls and form separate genetic lineages.

Can each lineage be diagnosed as the smallest unique evolutionary unit using DNA data?

Phylogenetic Species Concept

Kaibab squirrels live on the north rim and Abert's squirrels on the south rim of the Grand Canyon.

Did the formation of a geographic barrier lead to divergence between these populations?

Allopatric Species Concept

Rhagoletis flies shifted from hawthorn to apple hosts but remain in the same geographic region.

Did divergence in host plant use lead to reproductive isolation without geographic separation?

Sympatric Species Concept

Cichlid fish in Lake Victoria differ in mating coloration and female preference.

Did divergence in mate choice cause reproductive isolation within the same lake?

Sympatric Species Concept

Ensatina salamanders form a ring of populations around California’s Central Valley.

Did gradual divergence along a geographic range lead to reproductive isolation?

Parapatric

Genome duplication creates polyploid plants that cannot reproduce with the original population.

Can new species arise instantly within the same geographic area through genome duplication?

Sympatric