AMHERST, Mass. A new study involving bat skulls, bite force measurements and scat samples collected by an international team of evolutionary biologists is helping to solve a nagging question of evolution: Why some groups of animals develop scores of different species over time while others evolve only a few. Their findings appear in the current issue of Proceedings of the Royal Society B: Biological Sciences.
To answer this question, Elizabeth Dumont at the University of Massachusetts Amherst and Liliana Dvalos of Stony Brook University together with colleagues at UCLA and the Leibniz Institute for Zoo and Wildlife Research, Berlin, compiled large amounts of data on the diet, bite force and skull shape in a family of New World bats, and took advantage of new statistical techniques to date and document changes in the rate of evolution of these traits and the number of species over time.
They investigated why there are so many more species of New World Leaf-Nosed bats, nearly 200, while their closest relatives produced only 10 species over the same period of time. Most bats are insect feeders, while the New World Leaf-Nosed bats eat nectar, fruit, frogs, lizards and even blood.
One hypothesis is that the evolution of a trait, such as head shape, that gives access to new resources can lead to the rapid evolution of many new species. As Dumont and Dvalos explain, connecting changes in body structure to an ecological opportunity requires showing that a significant increase in the number of species occurred in tandem with the appearance of new anatomical traits, and that those traits are associated with enhanced resource use.
"If the availability of fruit provided the ecological opportunity that, in the presence of anatomical innovations that allowed eating the fruit, led to a significant increase in the birth of new species, then skull morphology should predict both diet and bite force" they said. They found support for
|Contact: Janet Lathrop|
University of Massachusetts at Amherst