Dissertation Research: Cold Comfort - Functional Diversification in Seasonal Environments

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How do plant communities that have adjusted to unvarying favorable conditions -- steady warmth and ample water ? adapt to the development of seasonally stressful conditions, such as dry or cold periods? Answering this question is all the more important as ecosystems worldwide undergo climatic shifts matched only in long-ago geological epochs. This research will study ancient Australian forest communities that predate the deserts and eucalyptus trees that are well known members of the plant communities on this continent. These communities, which descended from wet-tropical forests found across eastern Australia during the Eocene (~55 million years ago,) faced significant adaptive challenges as climates became cooler and dryer during the Oligocene (~33 million years ago.) Today, the plants found in seasonally-dry and cool-temperate forests are very different from those found in wet-tropical forests. This study examines two alternative hypotheses for how these communities formed: did the tendency for close relatives to resemble one another lead to communities composed of pre-adapted, closely-related plants? Or did adaptive convergence result in communities of distantly-related plants that have nonetheless become ecologically similar?Studying functional traits in seasonally dry and seasonally cold environments provides an opportunity to explore natural selection under environmental conditions that are potentially lethal for a large part of the year. By contrasting tropical and temperate environments, the project also explores mechanisms behind the contrast in biodiversity between tropical and temperate regions, a major unanswered question in biology. Understanding the exact functional distinctions that allow plants to survive dry and cold seasons also has important implications for predicting future responses to environmental change. The graduate student is sharing the excitement of this research with students across the US by sending "Reports from the Field", including postcards, photographic slide shows, and web-based videos, to biology classes from grades 3-12. Students are invited to join the process of investigation through an interactive wiki site.