I presume you mean, how does a new species form?...
A group of one species get seperated from another, and circumstance change. shall we say... the tempertature rises? this one group (in a high temperature) will have an advantage if they have less fur, for they will not be as hot, therefore they become 'desirable mates' and through many generations the species has less fur, becoming an altogether seperate species than it started
Yes, geographic barriers guarantee the formation of new species.
macroevolution
The formation of a new species
macroevolution
The phenomenon is called speciation.
the formation of species
Reproductive variation.
DNA
speciation
The general term for the formation of a new species is speciation.
reproductive isolation
Reproductive isolation