Examine the following scenario:

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 time.

there is a steady rise in the population of bright-colored fish. both populations thrive.

suppose that a short land barrier separates lake a from another small lake with a population of only the normal dark-colored fish (lake b). after torrential rains lasting for days, the lakes overflow and a few of the bright-colored fish from lake a are washed into lake b.

list the sequence of evolutionary mechanisms which have come into effect in each event.

a. genetic drift, mutation, natural selection
b. mutation, founder principle, bottleneck effect
c. mutation, natural selection, migration (gene flow)