SPECIATION

Speciation is the formation of a new species.

Species = A group of organisms with similar morphology, physiology and behaviour which can interbreed and are reproductively isolated from other species.

For a new species to arise, a group of individuals has to be reproductively isolated from the rest of the population. There are many factors, in addition to geographical isolation, why two species may not be able to breed and produce fertile offspring:

Ecological isolation: Species occupy different habitats
Temporal isolation: Species reproduce at different times
Behavioural isolation
Physical isolation: Physical factors preventing them from mating
Hybrid inviability: Hybrids produced but don’t live long enough to reproduce
Hybrid sterilisation: Hybrid survives long enough to breed but is infertile