A comment in Conservation Biology this month ((D.K. Skelly et al. (2007) Evolutionary Responses to Climate Change. Conservation Biology 21 (5), 1353–1355. doi:10.1111/j.1523-1739.2007.00764.x)) criticizes a recent paper in the same journal ((J.R. Malcolm (2006) Global Warming and Extinctions of Endemic Species from Biodiversity Hotspots. Conservation Biology 20 (2), 538–548. doi:10.1111/j.1523-1739.2006.00364.x)) which estimated that up to 43% of the endemic biota in some biodiversity hotspots could go extinct as a result of global climate change.
While not disputing that climate change will cause extinctions, the authors of the comment suggest that the climate envelope approach to predicting range changes ((That’s the same kind of approach that’s been used by our friend Andy Jarvis and others to predict dire consequences for the wild relatives of the peanut, potato and cowpea.)) ignores the possibility that species may in fact evolve in response to changes in the climate. And they quote evidence that such genetic change is happening.
There is nothing particularly new in this criticism — though that doesn’t mean it shouldn’t be repeated. Most papers that use climate envelope modeling to predict distributional shifts of species under climate change premise their discussion by saying something along the lines that what they’re presenting is a worst case scenario. It is what would happen if species could not move fast enough or adapt fast enough. They might not be able to adapt fast enough in particular if they lacked genetic variation, for example because of small effective population sizes.
So, that climate envelope studies may overestimate extinctions is generally recognized, I think. But the authors of the comment also point out that this focus on biodiversity extinction means that studies have overlooked “what may be the most pervasive effect of climate change: as species evolve in a changing world, genetic responses may render them forever different.”
That’s going to be particularly important for agrobiodiversity, as the genetic diversity that will be lost may be important to us in the future to feed the world. Another reason to be thankful for that insurance policy ((Thanks to the Trust’s science coordinator for permission to swipe that cliche.)) that are the genebanks of the world…