Ins and Outs of Extinction

Abstract

The global extinction of a species is the end point of a series of smaller-scale local extinctions of populations. Hence, the causes of extinction can be understood by studying patterns of extinction at the local scale. Species vary in their intrinsic vulnerability to extinction, and there is a range of extrinsic factors that can influence a population's survival; the probability of extinction might depend on the interplay of these two broad considerations. To study these questions, Fréville et al. took advantage of the Park Grass experiment, in which the fate of populations of herbaceous plants subjected to different fertilizer treatments have been followed for 60 years at a site in southeast England. The interactions of 11 intrinsic factors (life-history traits relating, for example, to reproduction and growth) with four extrinsic factors (such as nitrogen enrichment and acidification) were investigated. It transpired that population extinction could in most cases be related to the interaction of just one life-history trait with one extrinsic factor, but that the pairs of factors differed in different species. These findings point the way to a more accurate and predictive science of extinction, which will in turn provide a new tool for conservation managers attempting to reduce the rate of local extinctions caused by human activity. — AMS