The importance of behavioral separation as a mechanism for promoting sympatric speciation in a heterogeneous or patchwork landscape is highlighted in John Maynard Smith's seminal paper on sympatric speciation.
Through DNA comparison, scientists believe the Pan / Homo divergence occurred between 5.4 and 6.3 million years ago, after an unusual process of speciation that ranged over 4 million years.
But even in the Selenidera toucanets which, though largely sedentary, are technically able to disperse widely, the Amazon River forms a barrier that was simply too wide to cross in significant numbers as to inhibit speciation.
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The genus Selenidera was used by the German biologist Jürgen Haffer as an example of the "refugia" hypothesis of speciation.
In contrast to Ernst Mayr's interpretation of speciation by splitting, particularly allopatric and peripatric speciation.