Species are categorized:

Morphologically: if they appear identical physically

Biologically: interbreeding and producing fertile offspring

Evolutionary: Interbreeding groups are reproductively isolated and evolve separately from each other.

Speciation: When new biological species are created

What has to happen for the lineage to split?

Just small genetic differences are enough for speciation to occur. This can be change in location, time and mating rituals. This happens when they are reproductively isolated.

Alopatric Speciation: Popukations of species become isolated due to geographic separation. This is caused by a barrier, or something extrinsic which doens’t let the 2 groups mate with each other.

ex. mountain ranges, valleys, land

Sympatric Speciation: Two separate species evolve even thought they share the same geographic rea. Does not require large distance like alopatric and reduces gene flow.

Adaptive Radiation: Single species evolve into multiple diffrent but closely related species. Each new species fills a diffreent ecological niche, and occurs when a variety of resources arise.