Statement: Allopatric models of speciation follow Occam’s Razor in the sense that they require minimal assumptions to allow populations to evolve separate traits. For example, once populations are separate, only a single simple process like drift is necessary to drive differentiation (phenetic concept), evolution of novel characters (phylogenetic concept), or even permanent breeding barriers (biological species concept). It doesn’t mean that other factors don’t participate (e. g., selection, mutation), but it doesn’t require them. Sympatric models (which don’t physically separate populations) require more assumptions, usually needing to invoke at least two additional assumptions. These are usually:A) That sister species are each other's closest relative. B) Selection against hybrids and assortative mating. C) Ploidy level shifts