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Rapid Genetic Change in Terrestrial Plants
Volume 11, Number 25: 18 June 2008

Some fifteen years ago, Root and Schneider (1993) wrote that CO2-induced changes in global climate were expected to occur "too fast for evolutionary processes such as natural selection to keep pace," and that this constraint "could substantially enhance the probability of extinction of numerous species."

This idea has pervaded the thinking of climate-alarmists ever since it was first suggested; and it figures prominently in the ongoing doom-and-gloom predictions of Al Gore and James Hansen. But is it correct? In an exciting new paper recently published in Global Change Biology, Jump et al. (2008) describe an experiment that suggests the contention is fatally flawed.

In Barcelona, Spain's Garraf Natural Park, where they worked with Fumana thymifolia -- a small shrub that occurs around the Mediterranean Basin -- the seven scientists say they "investigated whether reduced seedling establishment observed as a consequence of climate manipulation is a random or selective process, thereby allowing us to answer the key question: does climate change provoke evolutionary change within natural populations?"

Their study had an unaltered control treatment, a drought treatment that employed automatically-activated transparent plastic shields that covered a third of the plots in response to rainfall and retreated when rainfall stopped (which decreased soil moisture by about 20%), and a warming treatment that employed reflective covers that reduced nighttime re-radiation of energy received from the sun during the prior daylight hours from another third of the plots (which increased temperature by about 1C).

As a result of these environmental interventions, Jump et al. report that over the 7-year period 1999-2005, mean yearly seedling density per treatment was significantly reduced in the drought and warming treatments compared with the control treatment, and that "when compared against control samples, high single-locus genetic divergence occurred in drought and warming treatment samples, with genetic differentiation up to 37 times higher than background (mean neutral locus) genetic differentiation."

In discussing their findings, the researchers say they suggest that the significant reduction in seedling survival they observed in the drought and warming treatments "results from an episode of selection for individuals tolerant of the modified climatic conditions and is not due simply to a random reduction in plant establishment," which implication, in their words, "reinforces results reported by other authors that show that genetic variability for climate-related traits exists within natural plant populations (Hamrick and Holden, 1979; Cobb et al., 1994; Kelly et al., 2003; Mitton and Duran, 2004; Franks et al., 2007)."

Jump et al. thus conclude that contemporary climate change "is driving changes in gene frequency within natural plant populations," and that these changes "are occurring on the same time scale as current climatic changes, based on preexisting genetic variability within populations," additionally citing, in this regard, the supportive findings of Jump and Penuelas (2005), Thomas (2005), Jump et al. (2006) and Reusch and Wood (2007). What is more, they say that this ability to rapidly adapt to rapid climate change may increase the persistence of species "beyond that predicted under a species-based climate envelope approach," such as is typically used by climate alarmists to justify their prediction of impending extinctions of huge numbers of species.

In a conclusion that clearly repudiates this catastrophic extinction scenario, Jump et al. say that their results actually demonstrate "that rapid evolution in response to climate change may be widespread in natural populations, based on genetic variation already present within the population," which likelihood is becoming ever more evident with each new study that investigates the subject.

Sherwood, Keith and Craig Idso

References
Cobb, N., Mitton, J.B. and Whitham, T.G. 1994. Genetic variation associated with chronic water and nutrient stress in pinyon pine. American Journal of Botany 81: 936-940.

Franks, S.J., Sim, S. and Weis, A.E. 2007. Rapid evolution of flowering time by an annual plant in response to a climate fluctuation. Proceedings of the National Academy of Sciences, USA 104: 1278-1282.

Hamrick, J.L. and Holden, L.R. 1979. Influence of microhabitat heterogeneity on gene frequency distribution and gametic phase disequilibrium in Avena barbata. Evolution 33: 707-711.

Jump, A.S., Hunt, J.M., Martinez-Izquierdo, J.A. and Penuelas, J. 2006. Natural selection and climate change: temperature-linked spatial and temporal trends in gene frequency in Fagus sylvatica. Molecular Ecology 15: 3469-3480.

Jump, A.S. and Penuelas, J. 2005. Running to stand still: adaptation and the response of plants to rapid climate change. Ecology Letters 8: 1010-1020.

Jump, A.S., Penuelas, J., Rico, L., Ramallo, E., Estiarte, M., Martinez-Izquierdo, J.A. and Lloret, F. 2008. Simulated climate change provokes rapid genetic change in the Mediterranean shrub Fumana thymifolia. Global Change Biology 14: 637-643.

Kelly, C.K., Chase, M.W., de Bruijn, A., Fay, M.F. and Woodward, F.I. 2003. Temperature-based population segregation in birch. Ecology Letters 6: 87-89.

Mitton, J.B. and Duran, K.L. 2004. Genetic variation in pinon pine, Pinus edulis, associated with summer precipitation. Molecular Ecology 13: 1259-1264.

Reusch, T.B.H. and Wood, T.E. 2007. Molecular ecology of global change. Molecular Ecology 16: 3973-3992.

Root, T.L. and Schneider, S.H. 1993. Can large-scale climatic models be linked with multiscale ecological studies? Conservation Biology 7: 256-270.

Thomas, C.D. 2005. Recent evolutionary effects of climate change. In: Lovejoy, T.E. and Hannah, L. Eds., Climate Change and Biodiversity, Yale University Press, Cambridge, Massachusetts, USA, pp. 75-88.