Gentoo penguins present a potential mate with a pebble. Emperor penguins have a specific call and movement that they make to attract a mate. Which type of isolation do these penguins demonstrate?

but there is no

i guess you forgot putting it.

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).