Invasive Species and the Loss of Beta Diversity

Why should we avoid introducing invasive species? In this paper I argue that in addition to the more ordinary and visible types of harm that invasive species cause, they also cause a reduction in a particular kind of biodiversity—that of beta diversity. Rather than simply measuring the number of species found in a particular region, beta diversity measures the differences in the species found between regions. This difference between regions can be measured by comparing neighboring regions (local beta diversity) or by comparing distant regions (global beta diversity). Both types of beta diversity are reduced by the introduction of invasive species. I further argue that beta diversity is an important part of our concept of biodiversity and of what we value about the natural world. Thus the tendency of invasive species to reduce beta diversity gives us a substantial reason to avoid introducing them.