Predicting extinction risk in declining species

What biological attributes predispose species to the risk of extinction? Th ere are many hypotheses but so far there has been no systematic analysis fo r discriminating between them. Using complete phylogenies of contemporary c arnivores and primates, we present, to our knowledge, the first comparative test showing that high trophic level, low population density, slow life hi story and, in particular, small geographical range size are all significant ly and independently associated with a high extinction risk in declining sp ecies. These traits together explain nearly 50% of the total between-specie s variation in extinction risk. Much of the remaining variation can be acco unted for by external anthropogenic factors that affect species irrespectiv e of their biology.