Children aren't the only youngsters who are picky eaters: More than half of all species are believed to change their diets -- sometimes more than once -- between birth and adulthood. And a new study by ecologists at Rice University and the University of California, Santa Barbara, finds this pattern has major implications for the survival of threatened species and the stability of natural ecosystems.
With thousands of species facing Earth's sixth major mass extinction, there is little doubt that the planet's biodiversity is in rapid decline. But many questions remain about how natural ecosystems will respond to the lost diversity. The new study, published online this week in Ecology Letters, challenges one of the standard assumptions that ecologists have used for decades to analyze the effects of biodiversity loss on ecosystems. That assumption -- that all food resources used by a species are interchangeable among all members of the species -- fails to account for the fact that diets change as young animals develop into adults, said Rice ecologist Volker Rudolf, one of the study's co-authors. The findings by Rudolf and co-author Kevin Lafferty suggest that changing dietary needs within species have important implications for ecosystem health.
"If a species has three resources in an ecosystem, and we take away one, conventional wisdom suggests that that species should be fine," said Rudolf, assistant professor in ecology and evolutionary biology. "But if the missing resource is crucial for a particular developmental stage of the species, that just doesn't work. You can't take away all of the adults, for example, or all of the larvae, and assume that the species will persist."
He said the new study was made possible by a wealth of information from recent datasets collected by Lafferty and colleagues at UC Santa Barbara. The datasets cover seven food webs --each representing the network of connections between dozens and, in some ca
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