In threespined sticklebacks small fish males with bright col

In three-spined sticklebacks (small fish) males with bright coloration are favored by females but their bright coloration puts those males at a higher risk of predation by muskies (predatory fish). What kind(s) of selection could explain bright coloration in sticklebacks?

a.) Group selection

b.) Sexual selection

c.) Balancing selection

d.) Sexual selection & Group selection

e.) Group selection & stabilizing selection

Solution

The answer is b) Sexual selection

The three-spined stickleback is a small fish that shows conspicuous sexual dichromatism and parental care during the breeding season; males develop bright orange-red body coloration and blue-green eyes. Females prefer more intensely red-colored males in simultaneous choice situations, which reveals his physical condition. In an experiment it was found that these males exhibit a greater diversity of Major Histocompatibility Complex (MHC, produce protein products that are essential for the functioning of the immune system). Males that have MHC genes are different from one another and will be superior when reproducing with regard to parasite resistance, body condition and reproductive success and survival.