A population of small fish lives in a lake (Lake A). The dark-colored fish are the ancestral phenotype and represent the usual coloration of the species. The bright-colored fish however arose over Tim?

The bright-colored fish in Lake A represent a variant phenotype that likely arose through a mutation or genetic variation. This change in coloration could provide advantages such as better camouflage from predators or increased attractiveness to mates, potentially allowing them to thrive in specific environments within the lake. Over time, if these advantages lead to higher survival and reproduction rates, the bright-colored fish may become more prevalent in the population, demonstrating natural selection in action.