Why do island chains provide ideal conditions for adaptive radiation to occur?
Organisms of one species can arrive to an island together and then disperse throughout the chain, each settling into different niches and exploiting different food resources to reduce competition.
Two species of fish had recently undergone sympatric speciation. The males of each species had a different coloring through which the females could identify and choose a partner from her own species. After some time, pollution made the lake so cloudy that it was hard for females to distinguish colors. What might take place in this situation?
It is likely the two species would start to reproduce with each other. Depending on the viability of their offspring, they may fuse back into one species.
Why can polyploidy individuals lead to speciation fairly quickly?
The formation of gametes with new n numbers can occur in one generation. After a couple of generations, enough of these new hybrids can form to reproduce together as a new species.