 As previously described, gradual genetic drift across populations (isolation by distance) and limited gene dispersal can account for some of the genetic and phenotypic divergence across populations, but there are alternative models besides isolation by distance that can contribute to these differences as well.Two of these alternate models include isolation by colonization and isolation by adaptation.The former is a product of colonization history and founder effects while the latter is a product of adaption to varying environments inhibiting migration between populations.