Conservation biology of two rattlesnakes, Crotalus willardi obscurus and Sistrurus catenatus edwardsii.

摘要

Anthropogenically exacerbated extinction rates are orders of magnitude above baseline and are rising rapidly, approaching and perhaps eclipsing those associated with the “terminal Cretaceous event.” In western North America many species with narrow ecological tolerances have experienced natural declines and reductions in range as a consequence of a rapid warming and drying trend since the last pluvial period. Where these species' habitat requirements and human interests conflict, population declines, extirpations, and extinction often result. At the species level, conservation science attempts to answer questions associated with the biology of these declines and to expose connections between imperiled species and their environment.; Elucidating patterns of neutral genetic variation among and within populations of imperiled species can facilitate delineation of populations and reveal structure within populations, as well as offer insights to recent evolutionary history and its relationship to landscape. Insights gained from these studies are especially useful when considering questions of translocation and can also be valuable in legislative and legal battles. Equally important to conservation of species, though often underappreciated, is an understanding of species' autecology. In many cases, basic natural and life history data have not been gathered.; In this research, patterns of variation at neutral DNA markers are explored in order to characterize relationships among and within populations of two endangered rattlesnakes [Crotalus willardi obscurus (New Mexico Ridgenose Rattlesnake) and Sistrurus catenatus edwardsii (Desert Massasauga)]. These data demonstrate that geographically discrete populations of both species are also genetically isolated and on independent evolutionary trajectories. These data also offer insights to the demographic history and genetic health of assayed populations. Within the context of these findings, conservation implications of natural and life history data (foraging ecology and reproduction) gathered over the course of two, five-year field studies are considered, as well as a specific threat to the woodland habitat of Crotalus willardi obscurus.