Evolutionary consequences of changes in species' geographical distributions driven by Milankovitch climate oscillations

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Abstract
We suggest Milankovitch climate oscillations as a common cause for geographical patterns in species diversity, species9 range sizes, polyploidy, and the degree of specialization and dispersability of organisms. Periodical changes in the orbit of the Earth cause climatic changes termed Milankovitch oscillations, leading to large changes in the size and location of species9 geographical distributions. We name these recurrent changes “orbitally forced species9 range dynamics” (ORD). The magnitude of ORD varies in space and time. ORD decreases gradual speciation (attained by gradual changes over many generations), increases range sizes and the proportions of species formed by polyploidy and other “abrupt” mechanisms, selects against specialization, and favor dispersability. Large ORD produces species prone neither to extinction nor gradual speciation. ORD increases with latitude. This produces latitudinal patterns, among them the gradient in species diversity and species9 range sizes (Rapoport9s rule). Differential ORD and its evolutionary consequences call for new conservation strategies on the regional to global scale.