Fragmented systems yielding small isolated populations suffer increased extirpation or extinction probabilities primarily from demographic processes ( Lande 1988 Woodroffe & Ginsberg 1998), and secondarily from more gradual genetic processes ( Frankham et al. Habitat fragmentation is a serious threat to biological diversity and is at the root of the present extinction crisis ( Wilcox & Murphy 1985).
They also demonstrate the ability of genetic analysis to detect gender-specific demographic population fragmentation in recently disturbed systems, a traditionally intractable yet increasingly important ecological measurement worldwide. Our results suggest that these trans-border bear populations may be more threatened than previously thought and that conservation efforts must expand to include international connectivity management. Two resulting populations are vulnerably small (≤100 animals) and one of these is completely isolated. Using individual-based genetic analysis, our results suggest this demographic connection has been severed across their entire range in southern Canada by a highway and associated settlements, limiting female and reducing male movement. inter-population movement of both sexes) to Canadian bears.
A tenet of grizzly bear conservation is that the viability of these populations requires demographic linkage (i.e. Grizzly bear range contraction in the conterminous USA has left four fragmented populations, three of which remain along the Canada–USA border. Therefore, if human-dominated landscapes fragment remaining carnivore populations, small and demographically vulnerable populations may result.
Large carnivores live at low densities and require large areas to thrive at the population level. Ecosystem conservation requires the presence of native carnivores, yet in North America, the distributions of many larger carnivores have contracted.
0 kommentar(er)
