Provide an example of how two populations could become isolated and explain how that isolation could lead to the evolution of a new species.

Ecological Isolation

Ecological, or habitat, isolation occurs when two species that could interbreed do not because the species live in different areas. For example, in India both the lion and tiger exist and are capable of interbreeding; however, the lion lives in the grasslands and the tiger lives in the forest. The two species live in different habitats and will not encounter one another: each is isolated from the other species.
Change in an organism's environment forces the organism to adapt to fit the new environment, eventually causing it to evolve into a new species. ... Isolation means that organisms of the same species are separated, and happens when there is something between the organisms that they can't cross.

Since a female is both xx chromosome and the male passes down the x chromosome, than the offspring would be female since a female is xx.