Project Title

Do amphibian populations at geographic range margins exhibit reduced capacities for phenotypic plasticity?

Department

Biological Sciences

Abstract

Rapid global climate is predicted to eliminate 11 – 17% of species by the end of the century, yet phenotypic plasticity may reduce extinction risk by buffering species from climate change. Such assumptions, however, contradict relationships between genetic diversity and range position, as geographically peripheral populations often exhibit reduced genetic diversity, resulting in populations that may be ill-prepared to withstand climate change. We assessed phenotypic plasticity in tadpoles (Cope's Gray Treefrog, Hyla chrysoscelis) from geographically central and peripheral populations in response to two ecological stressors: reduced hydroperiod and predation risk. Tadpoles from peripheral populations exhibited increased growth rates under predation risk and increased tail length: depth ratios, which indicate development towards greater thrust for escape from predators. Data from hydroperiod experiments are still being analyzed, but results to date indicate that peripheral populations may be just as capable, or even more capable, of phenotypically plastic responses to stress. While our findings are limited to small sample sizes from this pilot study, if such patterns are reinforced in more comprehensive future studies, a reconsideration of the hypothesized pattern of central-peripheral variation in phenotypic plasticity, and its roles in response to global climate change, may be necessary.

Presentation format

Poster

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Do amphibian populations at geographic range margins exhibit reduced capacities for phenotypic plasticity?

Rapid global climate is predicted to eliminate 11 – 17% of species by the end of the century, yet phenotypic plasticity may reduce extinction risk by buffering species from climate change. Such assumptions, however, contradict relationships between genetic diversity and range position, as geographically peripheral populations often exhibit reduced genetic diversity, resulting in populations that may be ill-prepared to withstand climate change. We assessed phenotypic plasticity in tadpoles (Cope's Gray Treefrog, Hyla chrysoscelis) from geographically central and peripheral populations in response to two ecological stressors: reduced hydroperiod and predation risk. Tadpoles from peripheral populations exhibited increased growth rates under predation risk and increased tail length: depth ratios, which indicate development towards greater thrust for escape from predators. Data from hydroperiod experiments are still being analyzed, but results to date indicate that peripheral populations may be just as capable, or even more capable, of phenotypically plastic responses to stress. While our findings are limited to small sample sizes from this pilot study, if such patterns are reinforced in more comprehensive future studies, a reconsideration of the hypothesized pattern of central-peripheral variation in phenotypic plasticity, and its roles in response to global climate change, may be necessary.