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Southern California Lizards Could Cope with Predicted Warming

Paper Reviewed
Barrows, C.W. and Fisher, M. 2014. Past, present and future distributions of a local assemblage of congeneric lizards in southern California. Biological Conservation 180: 97-107.

Barrows and Fisher (2014) begin their study of a local assemblage of congeneric lizards in southern California by stating "species and species assemblages extant today survived multiple past climate shifts throughout the Pleistocene." And in consequence of this fact, they say "their current distributions are in part the result of those fluctuating warm and cool climate cycles," citing the study of Woodruff (2010). But how did they do it?

One way could have been via migration or dispersal. But another potential mechanism could have been behavioral adaptation, whereby -- in the case of lizards -- the reptiles shuttle between Sun and shade to maintain a preferred body temperature (Tb) that is independent of ambient temperature, as described some time ago by Dawson (1967). More recently, for example, Lopez-Alcaide et al. (2014) discovered that "Sceloporus adleri can alter its thermoregulatory behavior to maintain its preferred Tb for key physiological processes when environmental temperatures were increased by 6°C."

And so it was that the two researchers constructed a set of habitat suitability models (HSMs) for an assemblage of four sympatric species of lizards within the genus Sceloporus -- S. magister, S. occidentalis, S. vandenburgianus, and S. orcutti -- in order to predict their distributions under three climate conditions: (1) the last glacial maximum of ca 20 kya, (2) the present, and (3) the end of the current century as forseen by the IPCC (2013). And what did they learn from this exercise?

Barrows and Fisher say their results suggest that the elevational heterogeneity of the landscape they studied "provided suitable habitat for these species throughout a past cold climate extreme and will likely continue to do so under predicted future warming." Even more generally, they conclude that their findings eliminate "the challenge for species with low dispersal capabilities to track rapidly changing climate envelopes." And that is good news for the survival of thess lizards.

Dawson, W.R. 1967. Interspecific variation in physiological responses of lizards to temperature. In: Milstead, W.W. (Ed.), Lizard Ecology Symposium, University of Missouri Press, Columbia, Missouri, USA, pp. 230-257.

IPCC. 2013. Climate Change 2013 - The Physical Science Basis. Contribution of the Working Group to the Fifth Assessment of the IPCC. Cambridge University Press, Cambridge, United Kingdom.

Lopez-Alcaide, S., Nakamura, M., Macip-Rios, R. and Martinez-Meyer, E. 2014. Does behavioural thermoregulation help pregnant Sceloporus adleri lizards in dealing with fast environmental temperature rise? Herpetological Journal 24: 41-47.

Woodruff, D.S. 2010. Biogeography and conservation in Southeast Asia: how 2.7 million years of repeated environmental fluctuations affect today's patterns and the future of the remaining refugial-phase biodiversity. Biodiversity and Conservation 19: 919-941.

Posted 14 April 2015