Sycamore / Pane

Sycamore trees (in the genus {Platanus) from Eurasian and North America can produce perfectly fertile hybrids, despite having been separated geographically by the Atlantic Ocean over tens of millions of years. Hybridizing the eastern Mediterranean Platanus orientalis with the eastern North America P. occidentalis gives us vigorous hybrids used as street trees in many temperate zone cities. Not only are the parental species still inter-fertile, the hybrids are fertile as well, despite millions of years of separation. Such realities discredit any claim that long term-isolation will necessarily produce genetically incompatible new species. In a time summary of speciation, Menno Schilthuizen concludes that "....scientific date are starting to support the notion that the impact of geographical isolation has been trivial rather than paramount." Surely there must be ways, other than broad-scale geographic isolation, by which populations can from new species.