What is the evolutionist viewpoint on speciation?

Question

Meaning, how do you define it, how does it work, and how does it contribute to evolution?

Answer 1

It's part of evolution.  What exactly was your question?

Answer 2

Speciation (the branching of a species into two daughter species) occurs when two subpopulations of a species get *genetically isolated* from each other.

This can be because of some geographical separation ... a river cuts through a valley, climate change dries up a valley between mountain ranges, a lake dries up into two lakes, an island drifts away from the mainland due to continental drift, etc. etc. etc.   This results in subpopulations losing contact with each other, and thus genetic isolation ... mutations that occur in one population have no way to spread to the other population ... and so the two accumulate very different genes over the centuries, and eventually lose the ability to interbreed ... they have become separate *species*.   This is called 'allopatric speciation'.

However, there are other mechanisms besides geographic isolation that can cause genetic isolation.   These have names like parapatric, peripatric, and sympatric speciation. (See source for more information, and good illustrations.)

Answer 3

Meaning, how do you define it, how does it work, and how does it contribute to evolution?

When one species diverges into 2 or more groups, and they stay separated for a long time.  Each evolves in it's own direction, until they are too different to interbreed anymore.  Or if they can breed, their offspring are infertile.  That's the definition and how it works.

But evolution contributes to speciation, not the other way around.