How are new species formed?
Scientists have recognized 3 distinct stages in the formation
of a new species......
Stage 1: A barrier to breeding.
One species may be split into 2 separate populations by some
sort of barrier which prevents the two populations from breeding together. Being
able to breed together keeps the DNA of 2 separate populations the same.
If a barrier prevents this mixing of genes, the 2 separate populations
may develop in different directions. Individuals with traits suitable to those
different habitats survive and pass on their DNA to their offspring, and the
DNA less suitable for survival disappears.
Long & Slichter