What the project is about?
Photo: Wilfredo Falcón
Several studies have suggested that tropical ectotherms (for example: Arthropods, fishes, amphibians, reptiles) should be especially vulnerable to climate warming. At first, this seems paradoxical, because the rate or warming in the tropics is actually less than at higher latitudes. However, tropical ectotherms in general are highly specialized for temperature (relative to higher-latitude species), and thus small changes in body temperature may have relatively large effects on the physiology and ecology of tropical species. If this expectation is correct, the implications are daunting, considering most of the world’s biodiversity is in the tropics.
One way to determine whether warming has already affected tropical ectotherms is to compare current biological patterns with historical patterns before recent warming occurred.
Anolis lizards in the Caribbean are ideal models for this kind of ‘before:after’ comparison because their ecology and physiology was exceptionally well studied during the 1970s and 1980s. Thus those old data provide a superb pre-warming baseline of ecological information.
Although several ‘before:after’ studies have been made in other systems, the scientists collecting contemporary data were not the ones who made the original studies. Thus, it isn’t clear whether an observed difference reflects a real ecological change, or merely a sampling artifact.
But in our projects, the same scientists who made that baseline research are coming back to Puerto Rico to replicate their earlier work. Thus any difference we observe should reflect change, not an observer artifact.
We are conducting two major surveys every year (one in summer and one in winter) to obtain basic data on thermal biology. We are attempting to determine whether environments are warmer than in the 1970s and 1980s, and whether the lizards themselves are warmer as well.
We are also monitoring reproductive phenology of these lizards, which reproduce all year except during winter. If warming is having an impact, we would expect to see that the non-breeding season in winter is shorter, and perhaps that reproduction in hot summer is reduced because of heat stress This work involves measuring reproductive status every month for Anolis cristatellus, Anolis gundlachi and Anolis cooki in different national parks and biological field stations (See Field Sites for more information).
In addition, at some sites food resources and feeding gains are being measured and compared to comparable data from the 1970s.
Some papers on Anolis that are relevant for the project are:
Deutsch, C. A., J. J. Tewksbury, R. B. Huey, K. S. Sheldon, C. K. Ghalambor, D. C. Haak, and P. R. Martin. 2008. Impacts of climate warming on terrestrial ectotherms across latitude. Proceedings of the National Academy of Science, USA105:6668-6672.
Dillon, M.E., G. Wang, and R. B. Huey. 2010. Global metabolic impacts of recent climate warming. Nature 467:704-706.
Gorman, G. C., and P. Licht. 1974. Seasonality in ovarian cycles among tropical Anolis lizards. Ecology 55:360-369.
Gorman, G.C. & S. Hillman. 1977. Physiological basis for climatic niche partitioning in two species of Puerto Rican Anolis (Reptilia, Lacertilia, Iguanidae). J. Herpetol. 11:337-340.
Gunderson, A. R., and M. Leal. 2012. Geographic variation in vulnerability to climate warming in a tropical Caribbean lizard. Functional Ecology 26:783–793.
Hertz, P.E. (1992). Evaluating thermal resource partitioning by sympatric lizards, Anolis cooki and A. cristatellus: a field test using null hypotheses. Oecologia, 90:127-136.
Hertz, P. E. (1992). Temperature regulation in Puerto Rican Anolis lizards: a field test using null hypotheses. Ecology, 73, 1405-1417.
Hertz, P.E., R.B. Huey, & R.D. Stevenson. 1993. Evaluating temperature regulation by field-active ectotherms: the fallacy of the inappropriate question. Am. Nat. 142:796-818.
Hoffmann, A.A. 2010. Physiological climatic limits in Drosophila: patterns and implications. J. Exp. Biol. 213:870-880.
Huey R. B., Webster T. P. (1976). Thermal biology of Anolis lizards in a complex fauna: the cristatellus group on Puerto Rico. Ecology 57:985-994
Huey R. B. (1974). Behavioral thermoregulation in lizards: importance of associated costs. Science 184:1001-1003
Huey, R.B., P.E. Hertz, & B. Sinervo. 2003. Behavioral drive versus behavioral inertia: a null model approach. Am. Nat. 161:357-366.
Huey, R. B., J. J. Tewksbury, C. A. Deutsch, L. J. Vitt, P. E. Hertz, and H. J. Alvarez Perez. 2009. Why tropical forest lizards are vulnerable to climate warming. Proceedings of the Royal Society, B. 276:1939-1948 doi:10.1098/rspb.2008.1957.
Huey, R.B., J.B. Losos, and C. Moritz. 2010. Are lizards toast? Science 328: 832-833.
Huey, R. B., M. R. Kearney,A. Krockenberger, J. A. M. Holtum, M. Jess, and S. E. Williams. in press. Predicting organismal vulnerability to climate warming: incorporating the buffering roles of behaviour, physiology, and adaptation. Philosophical Transactions of the Royal Society B.
Hoffmann, A.A. 2010. Physiological climatic limits in Drosophila: patterns and implications. J. Exp. Biol. 213:870-880.
Kearney, M., R. Shine, & W.P. Porter. 2009. The potential for behavioral thermoregulation to buffer "cold-blooded" animals against climate warming. Proc. Natl. Acad. Sci. USA 106:3835-3840.
Leal, M., & Gunderson, A. 2012. Rapid Change in the Thermal Tolerance of a Tropical Lizard. The American Naturalist, 180. 815-822
Licht, P. & G.C. Gorman. 1975. Altitudinal effects on the seasonal testis cycles of tropical Anolis lizards. Copeia 1975:496-504.
Lister, B.C. 1981. Seasonal niche relationships of rain forest anoles. Ecology 62:1548-1560.
Some papers that discuss the potential impacts of climate warming on tropical species are:
Sinervo, B., F. Méndez-de-la-Cruz, D.B. Miles, B. Heulin, E. Bastiaans, M. Vallagran-Santa Cruz, & R. Lara-Resendiz. 2010. Erosion of lizard diversity by climate change and altered thermal niches. Science 328:894-899.
Tewksbury, J. J., R. B. Huey, and C. A. Deutsch. 2008. Putting the heat on tropical animals. Science 320:1296-1297.
The project involves Professors and students from Universities from the United States, Puerto Rico and México, Is funded by NSF, and will be conducted over the years 2011-2014
One way to determine whether warming has already affected tropical ectotherms is to compare current biological patterns with historical patterns before recent warming occurred.
Anolis lizards in the Caribbean are ideal models for this kind of ‘before:after’ comparison because their ecology and physiology was exceptionally well studied during the 1970s and 1980s. Thus those old data provide a superb pre-warming baseline of ecological information.
Although several ‘before:after’ studies have been made in other systems, the scientists collecting contemporary data were not the ones who made the original studies. Thus, it isn’t clear whether an observed difference reflects a real ecological change, or merely a sampling artifact.
But in our projects, the same scientists who made that baseline research are coming back to Puerto Rico to replicate their earlier work. Thus any difference we observe should reflect change, not an observer artifact.
We are conducting two major surveys every year (one in summer and one in winter) to obtain basic data on thermal biology. We are attempting to determine whether environments are warmer than in the 1970s and 1980s, and whether the lizards themselves are warmer as well.
We are also monitoring reproductive phenology of these lizards, which reproduce all year except during winter. If warming is having an impact, we would expect to see that the non-breeding season in winter is shorter, and perhaps that reproduction in hot summer is reduced because of heat stress This work involves measuring reproductive status every month for Anolis cristatellus, Anolis gundlachi and Anolis cooki in different national parks and biological field stations (See Field Sites for more information).
In addition, at some sites food resources and feeding gains are being measured and compared to comparable data from the 1970s.
Some papers on Anolis that are relevant for the project are:
Deutsch, C. A., J. J. Tewksbury, R. B. Huey, K. S. Sheldon, C. K. Ghalambor, D. C. Haak, and P. R. Martin. 2008. Impacts of climate warming on terrestrial ectotherms across latitude. Proceedings of the National Academy of Science, USA105:6668-6672.
Dillon, M.E., G. Wang, and R. B. Huey. 2010. Global metabolic impacts of recent climate warming. Nature 467:704-706.
Gorman, G. C., and P. Licht. 1974. Seasonality in ovarian cycles among tropical Anolis lizards. Ecology 55:360-369.
Gorman, G.C. & S. Hillman. 1977. Physiological basis for climatic niche partitioning in two species of Puerto Rican Anolis (Reptilia, Lacertilia, Iguanidae). J. Herpetol. 11:337-340.
Gunderson, A. R., and M. Leal. 2012. Geographic variation in vulnerability to climate warming in a tropical Caribbean lizard. Functional Ecology 26:783–793.
Hertz, P.E. (1992). Evaluating thermal resource partitioning by sympatric lizards, Anolis cooki and A. cristatellus: a field test using null hypotheses. Oecologia, 90:127-136.
Hertz, P. E. (1992). Temperature regulation in Puerto Rican Anolis lizards: a field test using null hypotheses. Ecology, 73, 1405-1417.
Hertz, P.E., R.B. Huey, & R.D. Stevenson. 1993. Evaluating temperature regulation by field-active ectotherms: the fallacy of the inappropriate question. Am. Nat. 142:796-818.
Hoffmann, A.A. 2010. Physiological climatic limits in Drosophila: patterns and implications. J. Exp. Biol. 213:870-880.
Huey R. B., Webster T. P. (1976). Thermal biology of Anolis lizards in a complex fauna: the cristatellus group on Puerto Rico. Ecology 57:985-994
Huey R. B. (1974). Behavioral thermoregulation in lizards: importance of associated costs. Science 184:1001-1003
Huey, R.B., P.E. Hertz, & B. Sinervo. 2003. Behavioral drive versus behavioral inertia: a null model approach. Am. Nat. 161:357-366.
Huey, R. B., J. J. Tewksbury, C. A. Deutsch, L. J. Vitt, P. E. Hertz, and H. J. Alvarez Perez. 2009. Why tropical forest lizards are vulnerable to climate warming. Proceedings of the Royal Society, B. 276:1939-1948 doi:10.1098/rspb.2008.1957.
Huey, R.B., J.B. Losos, and C. Moritz. 2010. Are lizards toast? Science 328: 832-833.
Huey, R. B., M. R. Kearney,A. Krockenberger, J. A. M. Holtum, M. Jess, and S. E. Williams. in press. Predicting organismal vulnerability to climate warming: incorporating the buffering roles of behaviour, physiology, and adaptation. Philosophical Transactions of the Royal Society B.
Hoffmann, A.A. 2010. Physiological climatic limits in Drosophila: patterns and implications. J. Exp. Biol. 213:870-880.
Kearney, M., R. Shine, & W.P. Porter. 2009. The potential for behavioral thermoregulation to buffer "cold-blooded" animals against climate warming. Proc. Natl. Acad. Sci. USA 106:3835-3840.
Leal, M., & Gunderson, A. 2012. Rapid Change in the Thermal Tolerance of a Tropical Lizard. The American Naturalist, 180. 815-822
Licht, P. & G.C. Gorman. 1975. Altitudinal effects on the seasonal testis cycles of tropical Anolis lizards. Copeia 1975:496-504.
Lister, B.C. 1981. Seasonal niche relationships of rain forest anoles. Ecology 62:1548-1560.
Some papers that discuss the potential impacts of climate warming on tropical species are:
Sinervo, B., F. Méndez-de-la-Cruz, D.B. Miles, B. Heulin, E. Bastiaans, M. Vallagran-Santa Cruz, & R. Lara-Resendiz. 2010. Erosion of lizard diversity by climate change and altered thermal niches. Science 328:894-899.
Tewksbury, J. J., R. B. Huey, and C. A. Deutsch. 2008. Putting the heat on tropical animals. Science 320:1296-1297.
The project involves Professors and students from Universities from the United States, Puerto Rico and México, Is funded by NSF, and will be conducted over the years 2011-2014
And this, our life, exempt from public haunt, finds tongues in trees, books in the running brooks, sermons in stones, and good in everything.
William Shakespeare
William Shakespeare