How does isolation of gene pools lead to speciation, and how can reduced genetic variation in a changing environment lead to extinction?
1 Answer
see below
Explanation:
when two populations are isolated from each other:
there is genetic variation between the populations.
when the two populations live in different environments, there will be different alleles that give organisms a survival advantage.
only some organisms can survive due to competition, and so those without the survival advantage die, and those that have it can survive and breed to pass it on to their offspring.
since the two populations live in different environments, the alleles that last will be different.
since the selection of alleles is different for the two populations, the genetic variation between populations will increase.
eventually, their characteristics will be so different that the two populations can no longer interbreed to produce fertile offspring.
at this point, the two populations will be considered two different species.
in a changing environment:
if genetic variation is reduced, then most organisms will have similar alleles for certain characteristics.
this may mean that few organisms have an allele that would provide a survival advantage in a new environment.
a drastic change in environment could therefore kill most or all of a species, if few of them have adaptations to survive. they can die from lack of food or being unable to breed in due to the unusual environment.
