Can a single biological species arise more than once (i.e., polyphyletically)? How might this possibility depend on the nature of the reproductive barrier between such a species and its closest relative?
If speciation is primarily the result of allopatric processes, that is, dependent on geographic barriers blocking dispersal and gene flow, please give two reasons why the most species-rich animal group (insects) also one of the most mobile?
One of the most important questions in Evolutionary Biology is how does genic incompatibility between species evolve without simultaneously causing defects in pure species? A leading explanation is the Dobzhansky-Muller model of hybrid incompatibility. Please give an hypothetical example of how the Dobzhansky-Muller model works.