NSFDEB-NERC: Testing effects of resources and competitors at multiple spatial and temporal scales in multiple populations

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Almost all species are affected by competition with other species. In most cases, one species (the subordinate competitor) is more affected than the other (the dominant competitor), and competition can limit the population size or even cause local extinction of subordinate species. This happens in two ways. Most obviously, there are direct interactions such as the dominant competitor stealing food from the subordinate. Less obviously, there are costs to subordinates of avoiding direct interactions, for example, by moving away from an area with abundant food but where the dominant competitor is likely to be encountered. This research will use cutting edge technology to test how direct and indirect effects of competition affect the movements, energy gain and loss, survival, and reproduction of African wild dogs (Lycaon pictus) in areas with high and low numbers of their dominant competitor, the lion (Panthera leo), and with high and low numbers of prey. Because prey populations are declining in many areas of the world, understanding how changes in prey abundance alter the effect of competition is essential for conservation and management.It is widely recognized that prey populations can be limited not only by direct predation, but also by the costs of avoiding predation (‘risk effects’). Logic suggests that risk effects might also exist in competitive interactions. This project will test whether the avoidance of risk carries energetic costs that translate into effects on survival, reproduction, population dynamics, and gene flow in a subordinate competitor, the African wild dog. The project will incorporate new methods into long-term studies of African wild dog, lion, and prey populations in three ecosystems. Specifically, direct observation of wild dogs will be coupled to data from GPS collars, high frequency triaxial accelerometers, and magnetic field intensity sensors to obtain very fine-scaled data on movement, dynamic body acceleration, energy expenditure, and energy gain for wild dogs hunting in areas with known densities and distributions of lions and prey. Triaxial accelerometers will provide detailed and precise measurements of vectorial dynamic body acceleration (VeDBA) and energy expenditure at time scales ranging from seconds to days or months. GPS collars will provide inferences on space use and movement from dynamic Brownian bridge movement models (dBBMMs) at time scales from hours to years. dBBMMs or other movement models fit to trajectories derived from a combination of VeDBA, magnetic field intensity, and GPS locations will test for effects on movement down to the scale of seconds. Direct observation of the same individuals in continuous three-day ‘follows’ will provide spatiotemporally matched data on encounters with prey, hunts, and kills to quantify energy gain at time scales from hours to years, and will provide critical context for the interpretation of other data. By pairing these data with intensive, long-term monitoring of known individuals, relationships with survival, reproduction, and population dynamics can be tested using a Bayesian integrated population model, and effects on gene flow understood by using a SNP chip already developed and validated. Data for a range of ecological conditions will be collected through replication of the study across three ecosystems with well-measured variation in the densities of competitors and prey. This research is co-funded in part by the Behavioral Systems Cluster in the Division of Integrative Organismal Systems.This project is jointly funded between the Division of Environmental Biology and the Division of Integrative Organismal Systems (BIO).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.