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Alpine Plants Threatened with Warming-Induced Extinction
Gonzalo-Turpin, H. and Hazard, L. 2009. Local adaptation occurs along altitudinal gradient despite the existence of gene flow in the alpine plant species Festuca eskia. Journal of Ecology 97: 742-751.

The authors write that "the Pyrenean alpine ecosystem," which separates France from Spain, "is threatened by global warming and ... its associated species are at risk of extinction." Or as NASA's James Hansen has described the hypothetical phenomenon more generally, life in alpine regions is in danger of being "pushed off the planet," as it has "no place else to go."

What was done
In exploring this hypothesized threat in some detail, Gonzalo-Turpin and Hazard "examined the roles of genetic differentiation, gene flow and phenotypic plasticity in explaining the phenotypic variation along an altitudinal gradient of Festuca eskia Ramond, a perennial alpine grass endemic to the Pyrenean massif." This they did by means of a reciprocal transplant experiment involving 180 individuals along three altitudinal gradients (from 1500 to 2500 m), wherein they characterized various survival, functional and reproductive traits.

What was learned
The two researchers report that "genetic differentiation attributable to selection was detected in all traits between populations along the altitudinal gradient despite the existence of restricted gene flow," and that "evidence of co-gradient variation between genetic differentiation and plastic response was found for all traits except specific leaf area, suggesting that adaptive phenotypic plasticity operates in F. eskia." This finding is extremely important, for they note that "phenotypic plasticity is particularly important for the adaptive potential of long-lived alpine plants since it allows these organisms to accommodate rapid change in local environmental conditions," citing the work of Schlichting and Pigiucci (1998) and Sultan (2000).

What it means
The French scientists say their work "challenges common hypotheses on the lack of local adaptation of plant populations in fragmented mountain ranges, or on gene flow impeding differentiation," concluding that "the coexistence of genetic differentiation, gene flow and phenotypic plasticity along altitudinal gradients provides an adaptive potential for a grass species like F. eskia to successfully adapt to climate change."

Schlichting, C.D. and Pigliucci, M. 1998. Reaction norms and phenotypic plasticity. Phenotypic Evolution: A Reaction Norm Perspective, pp. 51-84.

Sultan, E.S. 2000. Phenotypic plasticity for plant development, function and life history. Trends in Plant Science 5: 537-542.

Reviewed 23 September 2009