Extinction filters and current resilience: the significance of past selection pressures for conservation biology.

There is now little reasonable doubt about the scale of the present extinction crisis: recent and ongoing rates of species loss exceed background levels by two to three orders of magnitude. Nevertheless, species differ widely in their vulnerability to current threats. Growing evidence from both palaeontology and conservation biology suggests that past events may help to explain this variation. Communities appear far more resilient to particular threats if they have faced similar challenges in the past. This intuitive but poorly reported phenomenon has potentially far-reaching implications for attempts to focus conservation efforts on those areas most at risk from contemporary human activity.