AMHERST, Mass. Introducing a new approach that combines evolutionary and engineering analyses to identify the targets of natural selection, researchers report in the current issue of Evolution that the new tool opens a way of discovering evidence for selection for biomechanical function in very diverse organisms and of reconstructing skull shapes in long-extinct ancestral species.
Evolutionary biologist Elizabeth Dumont and mechanical engineer Ian Grosse at the University of Massachusetts Amherst, with evolutionary biologist Liliana Dvalos of Stony Brook University and support from the National Science Foundation, studied the evolutionary histories of the adaptive radiation of New World leaf-nosed bats based on their dietary niches.
As the authors point out, adaptive radiations, that is, the explosive evolution of species into new ecological niches, have generated much of the biological diversity seen in the world today. "Natural selection is the driving force behind adaptation to new niches, but it can be difficult to identify which features are the targets of selection. This is especially the case when selection was important in the distant past of a group whose living members now occupy very different niches," they note.
They set out to tackle this by examining almost 200 species of New World leaf-nosed bats that exploit many different food niches: Insects, frogs, lizards, fruit, nectar and even blood. The bats' skulls of today reflect this dietary diversity. Species with long, narrow snouts eat nectar, while short-faced bats have exceptionally short, wide palates for eating hard fruits. Species that eat other foods have snouts shaped somewhere in between.
Dumont explains further, "We knew diet was associated with those things, but there was no evidence that natural selection acted to make those changes in the skull. The engineering model allowed us to identify the biomechanical functions that natural select
|Contact: Janet Lathrop|
University of Massachusetts at Amherst