Two pods of dolphins (same species) exist off the coast of Mexico. Pod A likes to swim and play at depth in cooler water. Pod B likes to play on the crests of waves, preferring to stay a little closer to the light. Eventually the two pods preferentially choose mates which exhibit the same preference for swimming depth. Over time they lose the ability to interbreed. This speciation event is

The correct answer is - speciation is sympatric.

Explanation:

Sympatric speciation is a process of speciation that takes place when there is reproductive isolation between two populations of a species without any geographical separation.

This speciation takes place in the population with come ancestors as given in the question both pods of dolphins lose their ability to interbreed due to the sympatric speciation without any geographical separation.

Thus, the correct answer is - speciation is sympatric.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).