Green-eyed Tree Frog Speciation

After a million years of being geographically isolated, the northern and southern populations of the green-eyed tree frog Litoria genimaculata met again 8,000 years ago, each had changed in subtle ways. The calls of the male frogs were different, and more importantly, the offspring of a north-south pairing didn't survive well. One population that was cut off from its southern kin (isolated south) found a way to ensure healthy young. Isolated southern females selected southern males by virtue of their distinctive call. The preference resulted in rapid speciation between the two populations of southern frogs.

This type of reinforcement of natural selection has been controversial since Darwin's time, but researchers supported by NSF and the Australian Cooperative Research Centre for Tropical Rainforest Ecology and Management have published data to support the concept.