Understanding functional connectivity in shortgrass and mixedgrass prairies using the swift fox as a model organism
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Habitat fragmentation and loss are the greatest sources of biodiversity loss today. The negative relationship between these phenomena and myriad ecological processes are well-documented. Chief amongst these impacts is the disruption of dispersal regimes, resulting in isolated or semi-isolated groups. Reduced dispersal in turn negatively influences gene flow between groups of individuals, resulting in reduced genetic diversity, increasing risk of inbreeding depression and, ultimately, heightened extinction risk. Thus, maintaining functional connectivity in ecosystems is high on the list of conservation priorities. The Great Plains is a vast ecosystem characterized by habitat fragmentation natural and anthropogenic in origin. Remnant shortgrass and mixedgrass prairies, in which this study occurs, have been reduced to < 50% of their previous extensive geographic area, largely due to agricultural development. Anthropogenic impacts on connectivity are predicted to increase, resulting in loss of up to 50% of remnant native grasslands. Thus, understanding these factors’ influence on grassland connectivity is critical for conservation and management in both contemporary and future time scales. Here, I employed a landscape genetics approach to address a series of objectives, which include assessing current and historic genetic diversity and structure in swift fox populations, relating gene flow and genetic structure patterns to landscape influences, and providing insight into conservation needs for the species. In addition, I used the swift fox as a model species to elucidate connectivity patterns across two focal areas in the shortgrass and mixedgrass prairies, ultimately presenting functional connectivity maps for these regions. Finally, I developed a new method for studying connectivity networks in fragmented populations with empirically derived cost metrics, and demonstrated its utility for identifying movement corridors using least-cost path modeling; this analysis was conducted in a fragmented swift fox population wherein genetic diversity appears to be linked to inter-population movement; thus identification of movement corridors is a critical conservation need locally.