CGL2011-27469 - Conducta espacial y mecanismos de coexis

The grey fox and the culpeo fox occur in disjunct ranges over most of South America but coexist in southern Patagonia. Coexistence might have occurred only recently if culpeos (three times heavier than grey foxes and hence the superior competitor) had invaded the area due to throphic subsidies supplied since European colonization 200 years ago. We shall estimate fox regional distribution and its dynamics, the relative abundance of fox species and their trophic resources, the availability of potential refuges, and patterns of fox spatial bahaviour in order to test predictions of four paradigms of coexistence of competitors. Neutral theory predicts stochastic distributions for both species and, therefore, a random distribution of coexistence. Patch dynamics theory does not allow local coexistence but predicts regional coexistence if species trade-off competitive ability and colonization ability. Species sorting theory predicts spatial, temporal, or habitat segregation, or any other difference in life history traits that confer to one of the species a competitive advantage in some habitats but not others. Mass effects theory allows for coexistence if populations of the inferior competitor persist at a negative growth rate sustained by immigration (sink). We will also address equivalent predictions regarding spatial behaviour, paying special attention to the pattern of interactions between heterospecifics through the analysis of simultaneous trajectories.