Coping with environmental change: the importance of adaptive thermoregulatory flexibility for Malagasy bats

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The energy budgets of animal species are closely linked to their environment. Species that occur in habitats with differing ecological and climatic conditions must be able to flexibly cope with these varying conditions. This holds also true for changes owing to seasonality, human-caused fragmentation or global climate change that can be challenging, because they often involve increased energy requirements. Madagascar is particularly affected by anthropogenic changes, as > 90% of the original environments are already altered. Despite their important ecosystem services and their great contribution to the preservation of ecosystems, and the acute threat to their natural habitat, surprisingly little is known about Malagasy bats.The major objective of this project is to examine the energy management of Malagasy bat species, especially Hipposideros commersoni, related to varying and changing environmental conditions, roost choice, and parasite load. The species investigated live in the most arid and unpredictable zone of the island, which undergoes drastic seasonal changes in ambient temperature, precipitation and resource availability. Therefore, we will examine the energy budgets and thermal biology of the bats directly in the field and relate these physiological parameters to local environmental characteristics, and compare them in two habitats with different roosting possibilities (cave vs. tree hollows), leading to very different microclimatic conditions, to draw conclusion on the flexibility of these physiological responses. We also document occurrence and intensity of heterothermy, one of the most powerful responses for small, endothermic mammals to cope with energy and water bottlenecks. Our study will contribute new information about the ecological and physiological demands and responses of bat species inhabiting extreme environments, which is crucial for the identification of habitat characteristics critical for the survival of mammals in general. Moreover, our results will enable reliable predictions about the capacity of bats to endure environmental and climatic change. Last but not least, our results will enable us to make comparisons with 1) temperate and tropical bats from other regions and continents and 2) the well-documented torpor patterns of Malagasy lemurs. These comparisons will allow us to address important, unanswered questions on the evolution of mammalian thermoregulation and the variability and possibly plesiomorphic character of heterothermy.