Background
The authors write that in response to projected global warming, "it is estimated that 59% and 98% of South African and European reptiles, respectively, will become extinct or will undergo range retraction if they cannot change their [latitudinal] distributions," citing Thomas et al. (2004) and Araujo et al. (2006). And they note, in this regard, that Hickling et al. (2006) found that "the distribution limits of two reptiles (Lacerta agilis and Natrix natrix) in the United Kingdom are not changing as temperature increases."

What was done
Wondering about their own country, the four Spanish researchers say they "used data on the distributions of reptiles in Spain during the 20th century to analyze whether the distributions of these reptiles have changed as climate has changed." This they did by comparing "the distributions of reptile species before 1975" - the year when they say that according to the IPCC (2007) the current period of warming began - "with distributions during 1991-2005."

What was learned
Moreno-Rueda et al. report that "after controlling for sampling effort, geographic bias in sampling, phylogeny, and spatial autocorrelation, the northern limits of the distribution of reptiles in Spain shifted northward between 1940-1975 and 1991-2005," but they say "there was no similar shift southward in the southern limits of species' ranges." In addition, they indicate that the mean latitude of the ranges of the species they examined "shifted northward by an equivalent of 0.5 km/year, which is similar to the magnitude of range shifts in other taxonomic groups (Parmesan and Yohe, 2003)."

What it means
Noting that they were "the first to show there is a correlation between changes in latitudinal distribution and increases in temperature for a wide variety of species of reptiles in Spain," the four researchers say their "finding that reptiles are expanding their northern ranges, potentially in response to climate change, could mean the probability of extinction associated with increases in temperature may be lower than expected." In fact, with their ranges expanding, Spain's reptiles could soon be doing even better than they have in the past.

References
Araujo, M.B., Thuiller, W. and Pearson, R.G. 2006. Climate warming and the decline of amphibians and reptiles in Europe. Journal of Biogeography 33: 1712-1728.

Hickling, R., Roy, D.B., Hill, J.K., Fox, R. and Thomas, C.D. 2006. The distributions of a wide range of taxonomic groups are expanding polewards. Global Change Biology 12: 450-455.

IPCC. 2007. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the IPCC, Solomon, S., Qin, D., Manning, M., Chen, Z. Marquis, M., Averyt, K., Tignor, M. and Miller H.L. (Eds.). Cambridge University Press, New York, New York, USA.

Parmesan, C. and Yohe, G. 2003. A globally coherent fingerprint of climate change impacts across natural systems. Nature 421: 37-42.

Thomas, C.D., Cameron, A., Green, R.E., Bakkenes, M., Beaumont, L.J., Collingham, Y.C., Barend, F., Erasmus, N., Ferreira de Siqueira, M., Grainger, A., Hannah, L., Hughes, L., Huntley, B., van Jaarsveld, A.S., Midgley, G.F., Miles, L., Ortega-Huerta, M.A., Peterson, A.T., Phillips, O.L. and Williams, S.E. 2004. Extinction risk from climate change. Nature 427: 145-148.