Allopatric Speciation in Oceans Questioned
From ScienceDaily:
“Most scientists believe that allopatric speciation, where different species arise from an ancestral species only after breeding populations have become physically isolated from each other, is the dominant mode of speciation both on land and in the sea. The key to this theory is the existence of some kind of physical barrier that operates to restrict interbreeding (gene flow) between populations so that, given enough time, such populations diverge until they’re considered separate species.
[...]
It has been theorized that the boundaries between these water masses act as barriers to the movement of plankton, which are organisms that cannot actively swim against currents, but instead drift with them. The existence of these supposed ‘barriers’ has resulted in the general assumption amongst scientists that allopatric speciation is the dominant mode of plankton diversification throughout the oceans. However, the new work published in the journal Geology suggests an altogether different picture.”
