Monday, August 1, 2011

Rapid Evolution in Island Frogs

Fanged frog guarding eggs. Photo credit:
Jimmy A. McGuire
Scientists led by Ben Evans of McMaster University have documented the rapid evolution of new fanged frog species on the island of Sulawesi, near the Philippines. The team found 13 species of fanged frog on the island, nine of which hadn't previously been described. The species differ in body size, amount of webbing in their feet, and even how they raise their young—all in accordance with the demands of their distinct ecological niches. Sulawesi has the same number of fanged frog species as the Philippine archipelago. "We would expect to find more species on the archipelago because it's so much larger, but that's not the case," Evans said. Why such diversity on the smaller island? There's less competition on Sulawesi, the researchers say. Fanged frogs in the Philippines have to compete with another genus of frogs, Platymantis. Platymantis never made to hop over to Sulawesi, leaving the fanged frogs free to spread out into new habitat niches, to which they eventually adapted. The rapid evolution of these frogs is a striking example of adaptive radiation—a concept Charles Darwin famously recorded in Galapagos finches.

Mohammad I. Setiadi, Jimmy A. McGuire, Rafe M. Brown, Mohammad Zubairi, Djoko T. Iskandar, Noviar Andayani, Jatna Supriatna, Ben J. Evans. Adaptive Radiation and Ecological Opportunity in Sulawesi and Philippine Fanged Frog (Limnonectes) Communities. The American Naturalist, 2011; 178 (2): 221 DOI:10.1086/660830

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