Drivers of marine biodiversity: Tiny, freeloading clams find the key to evolutionary success
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What mechanisms control the generation and maintenance of biological diversity on the planet? It's a central question in evolutionary biology. For land-dwelling organisms such as insects and the flowers they pollinate, it's clear that interactions between species are one of the main drivers of the evolutionary change that leads to biological diversity. But the picture is much murkier for ocean dwellers, mainly because the scope of ecological interactions remains poorly characterized for most marine species. In one of the first efforts to examine how species interactions drive diversification of ocean-dwelling organisms, two University of Michigan researchers and an Australian colleague looked at the lifestyle choices within an exceptionally diverse superfamily of tiny clams, the Galeommatoidea. "What was surprising was the overwhelming evidence that commensalism is associated with the soft-bottomed habitat. You seldom get such clear-cut data in an ecological study," said Jingchun Li, a doctoral student in the U-M Department of Ecology and Evolutionary Biology and first author of the PLoS ONE paper. "Jingchun's finding that the type of sea floor habitat strongly modulates the ecological importance of commensalism in these megadiverse clams gives us a novel insight into how ostensibly irrelevant background physical conditions may shape the evolution of species interactions in marine environments," said study co-author Diarmaid O'Foighil, Li's adviser and the director of the U-M Museum of Zoology.