How is lake or river that freezes over to the organisms in the water?

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population.b) the separated population is small, and genetic drift occurs.c) the isolated population is exposed to different selection pressures than the ancestral population.d) different mutations begin to distinguish the gene pools of the separated populations.e) gene flow between the two populations is extensive.

Can a trait be both polygenic and have multiple alleles? explain why or why not.

The pelican's beak is adapted for in .