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Community Ecology: physiological mechanisms of species co-existence
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We are answering the call to rebuild community ecology from functional traits, performance currencies, and fundamental and realized niches. The results are providing more rigorous and physiologically explicit predictions to deal with pressing issues of global change. Much of our research projects focus on ants, which rank among the most numerically abundant and ecologically dominant consumers on earth. This consumption is governed by the metabolic requirements of workers, which in turn depend on environmental temperature. However, little is known about how temperature shapes ant metabolic rates within and across populations. In a recent 2019 study published in Journal of Animal Ecology, my collaborators and I sought to better understand these thermal ecology dynamics, performing common garden experiments, comparing thermal reaction norms (Q10) of metabolic rate (MR) and behavior (activity levels) across populations of ant species arrayed along elevation gradients. We found support for the metabolic cold adaptation hypothesis, that high elevation ectotherms can quickly ramp up metabolic rates at cold temperatures to maximize foraging returns.
Bottom picture: I have established a respirometry system in my lab to measure the metabolic rates of insects and other ectotherms
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Co-evolutionary Eco-physiology
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Symbioses often involve food exchange among interacting partners, but the nutritional dimensions underlying these transactions are often difficult to parse. My lab group has developed techniques for using symbioses involving social insects as models for such inquiry. A main focus of our research is the remarkable lineage of attine ants, that have evolved diverse farming strategies for cultivating a range of fungal symbionts over their evolutionary history. Related research explores nutritional partnerships among fungus-farming termites (collaboration with the lab of Michael Poulsen), invasive Argentine ants and honeydew producing aphid mutualists (with Jules Silverman), and metabolic experiments to resolve the energetic costs of nematode parasites that induce berry mimicry in their ant hosts (with Steve Yanoviak and Mike Kaspari). A new collaboration with Henrik de Fine Licht and our co-supervised Masters student Zsuzsanna Csontos, is testing hypotheses about how nutrition governs host-specificity in insect pathogens.
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Nutritional dimensions in ecology
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The growth and survival of individuals and societies boils down to the acquisition of food. Despite this simple premise, foods are complex mixtures of water, inorganic elements, carbohydrates, proteins, toxins, etc. Eco-physiological approaches integrating food chemistry and consumer performance have long been dominated by simplified single-currency approaches on one end, and by detailed single-species approaches on the other. The emerging field of nutritional geometry (NG) has reconciled these perspectives in diverse taxa, providing new theory, methods (e.g. nutritionally defined diets) and new graphical tools (e.g. performance landscapes) for visualizing how foraging organisms prioritize multiple competing nutritional requirements. My lab is innovating new NG approaches to study ecological dynamics ranging from predicting invasive species success to studying the inner workings of insect societies. For instance, since workers must make collective decisions about how to prioritize the harvest of various foods whose nutritional content may be more beneficial for sustaining other nestmates. My lab uses a variety of approaches, from stable isotopes, to near infrared spectrometry, to understand these nutritional decisions.
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