Evolutionary rates of zooxanthellate and azooxanthellate corals and their controlling factors

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Our goal is to identify the underlying causes of evolutionary rates within scleractinian corals. Scleractinians have two fundamentally different ecologies: Those that retrieve a substantial proportion of their nutrition from symbiotic algae in their tissue (zooxanthellate corals) and those that entirely depend on zooplankton for feeding Proposal Kiessling 2 (azooxanthellate corals). We will be analyzing the evolutionary consequences of these different ecological modes and correlated traits such as coloniality and environmental affinity. While photosymbiosis is clearly beneficial at the organismic level, there is a trade-off in terms of evolutionary benefit because zooxanthellate reef corals seem to be more sensitive to environmental change and tended to be affected more strongly by extinction events than other corals. Evolutionary rates are measured by a novel combination of samplingstandardized biodiversity dynamics and molecular methods. The changes in diversification, speciation, and extinction patterns will be compared with global changes in the marine environment and evolutionary changes in ecology to learn more about the circumstances favoring the spread and demise of these different corals. Thereby, we expect to improve estimates of extinction risk of modern corals.