How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Climate-Driven Adaptations of Balsam Poplar Trees
Keller, S.R., Soolanayakanahally, R.Y., Guy, R.D., Silim, S.N., Olson, M.S. and Tiffin, P. 2011. Climate-driven local adaptation of ecophysiology and phenology in balsam poplar, Populus balsamifera L. (Salicaceae). American Journal of Botany 98: 99-108.

The authors note that "studies on the evolution of plant populations during historical fluctuations in climate can reveal the capacity for and constraints on adaptive evolution and may help inform predictions about evolutionary responses to future environments." Therefore ...

What was done
... they tested for adaptive variation in thirteen ecophysiology and phenology traits on clonally propagated genotypes of balsam poplar (Populus balsamifera L.) trees originating from a range-wide sample of 20 subpopulations that developed during the warming of climate conditions that marked the end of the last glacial maximum (~18 thousand years ago), when there was a rapid environmental change that increased population sizes and led to range expansions in many plant species, which "wave of migrations," in the words of Keller et al., "affected genomic diversity within populations, as colonists sub-sampled alleles from the ancestral gene pool during the process of expansion (Lascoux et al., 2004; Petit et al., 2004; Savolainen and Pyhajarvi, 2007)."

What was learned
The six scientists report that "evidence for divergence in excess of neutral expectations was present for eight of thirteen traits," and they say that "strong correlations were present between traits, geography [extending across the whole of Canada from the Atlantic to Pacific Oceans], and climate," revealing "a general pattern of northern subpopulations adapted to shorter, drier growing seasons compared with populations in the center or eastern regions of the range."

What it means
Keller et al. say their study "demonstrates pronounced adaptive variation in ecophysiology and phenology among balsam poplar populations," and they state that this result suggests that "as this widespread forest tree species expanded its range since the end of the last glacial maximum, it evolved rapidly in response to geographically variable selection." And, hence, it can be expected to do so again, as circumstances may warrant; for as they remark in the concluding sentence of their paper, "balsam poplar is both highly variable and capable of a broad range of adaptive physiological responses to a changing climate."

Lascoux, M., Palme, A.E., Cheddadi, R. and Latta, R.G. 2004. Impact of ice ages on the genetic structure of trees and shrubs. Philosophical Transactions of the Royal Society of London B, Biological Sciences 359: 197-207.

Petit, R.J., Bialozyt, R., Garnier-Gere, P. and Hampe, A. 2004. Ecology and genetics of tree invasions: From recent introductions to Quaternary migrations. Forest Ecology and Management 197: 117-137.

Savolainen, O. and Pyhajarvi, T. 2007. Genomic diversity in forest trees. Current Opinion in Plant Biology 10: 162-167.

Reviewed 25 May 2011