Speciation

Great decision! Your selection of bird blood for dinner ensures your place in the above-ground, or ancestral, species of mosquito. Thus, you thrive in the above-ground environment which is abundant in space and food. As these conditions include seasonal changes, your population tends to hibernate in winter, meaning feeding is more predominant throughout the other seasons.

You continue to breed with other above-ground, 'upper' class mosquito citizens without access to the mutant underground population, hence your alleles do not permit interbreeding.