Individual and population-level responses of the Alabama beach mouse (Peromyscus polionotus ammobates) to environmental variation in space and time

摘要

In Chapter two, I show that the giving up density of P. p. ammobates is related to nocturnal light intensity, temperature, and an interaction between light intensity and temperature. This is interpreted in terms of the intensity of perceived predation risk by snakes versus owls, as mediated by temperature-regulated physiological state of the mice. In Chapter three, I consider a source-sink system where disturbance momentarily reverses the dependency structure of these two areas. Specifically, I show how a sink can rescue a source, thereby increasing persistence of both. I further show that decelerating the rate of population decline in the putative sink population can result in large improvement in persistence relative to increasing the rate of post-disturbance carrying capacity in the putative source. The magnitude of this result depends on disturbances frequency. In Chapter four, I show the degree of spatial segregation of P. p. ammobates and the Hispid cotton rat (Sigmodon hispidus) at the scale of tens of meters. After removing S. hispdus from some locations, the distribution of P. p. ammobates appears to respond. This suggests that the realized niche of P. p. ammobates is influenced by a species 10 times its size, and I suggest the possibility that this interspecific competition could be a proximate cause of extinction of P. p. ammobates if hurricanes force both species into a few remaining habitat remnants. In Chapter five, I present an analysis of data on the detection/nondetection of P. p. ammobates collected over a four-year period immediately following Hurricane Katrina. I estimate the rate of post-hurricane recovery and show the effects of various remotely-sensed environmental covariates on rates of colonization and survival. In Chapter six, I use results from Chapter five to parameterize a spatially-explicit simulation of P. p. ammobates occupancy dynamics. The model suggests that the probability of extinction over 100 years increases very abruptly at a threshold level of habitat loss and hurricane frequency. The implications of the combined effects of global warming and human development on the future of P. p. ammobates is then discussed.