Volume 11, Number 8: 20 February 2008
Many are the horror stories of untold numbers of plant and animal species slated for imminent extinction because of catastrophic temperature increases claimed to be just around the corner or "in the pipeline," as James Hansen describes it, due to past and projected increases in anthropogenic CO2 emissions (Parmesan and Yohe, 2003; Root et al., 2003; Malcolm et al., 2006; to cite but a few). We have discussed at considerable length, and subsequently refuted, a number of these contentions in our major report The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere? One topic that is not broached there, however -- at least to any significant degree -- is that of evolutionary responses, which may be rapid enough to enable species to successfully cope with the degree and rate of global warming that is typically predicted by climate alarmists to be destined to occur somewhere in the very near future. Since that time, we have reviewed a number of papers that have indeed revealed the reality of such responses; and these reviews are now archived under the various sub-headings of Evolution in our Subject Index. In addition, we here discuss a number of pertinent observations made by Skelly et al. (2007) in a commentary they wrote for the journal Conservation Biology.
The group of seven scientists from the United States, Canada and Australia critiques the common technique of using the "climate-envelope approach" to predict extinctions, citing as their primary reason for doing so the fact that this approach "implicitly assumes that species cannot evolve in response to changing climate," when in numerous cases they can do so very effectively. Stating that "many examples of contemporary evolution in response to climate change exist," they report that "in less than 40 years, populations of the frog Rana sylvatica have undergone localized evolution in thermal tolerance (Skelly and Freidenburg, 2000), temperature-specific development rate (Skelly, 2004), and thermal preference (Freidenburg and Skelly, 2004)," while noting that "laboratory studies of insects show that thermal tolerance can change markedly after as few as 10 generations (Good, 1993)." Adding that "studies of microevolution in plants show substantial trait evolution in response to climate manipulations (Bone and Farres, 2001)," they go on to say that "collectively, these findings show that genetic variation for traits related to thermal performance is common and evolutionary response to changing climate has been the typical finding in experimental and observational studies (Hendry and Kinnison, 1999; Kinnison and Hendry, 2001)."
Although evolution will obviously be slower in the cases of long-lived trees and large mammals, where long generation times are the norm, Skelly et al. say that the case for rapid evolutionary responses among many other species "has grown much stronger (e.g., Stockwell et al., 2003; Berteaux et al., 2004; Hariston et al., 2005; Bradshaw and Holzapfel, 2006; Schwartz et al., 2006; Urban et al., 2007)." As a result, they write that "on the basis of the present knowledge of genetic variation in performance traits and species' capacity for evolutionary response, it can be concluded that evolutionary change will often occur concomitantly with changes in climate [our italics and bold] as well as [with] other environmental changes (e.g., Grant and Grant, 2002; Stockwell et al., 2003; Balanya et al., 2006; Jump et al., 2006; Pelletier et al., 2007)."
Consequently, and in summing up the implications of the many studies cited by Skelly et al., it can now be confidently concluded, as stated in the title of our editorial, that "global warming begets species-saving rapid evolutionary changes in many plants and animals."
Sherwood, Keith and Craig Idso
References
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