The Long-Distance Gene Flow of Trees

Kremer et al. (2012) say that "trees are capable of long-distance gene flow, which can promote adaptive evolution in novel environments by increasing genetic variation for fitness." However, they say that it is "unclear" if this phenomenon can compensate for "the long-generation times of trees." To further explore the subject, the thirteen researchers of this study who participated in a one-week workshop entitled "Forest Ecosystem Genomics Research" got together and produced a synthesis of the materials that were presented and discussed at the meeting relative to this important subject, the chief result of which was this publication, in which they say they "critically review data on the extent of long-distance gene flow and summarize theory that allows us to predict evolutionary responses of trees to climate change." So what did they conclude?

Noting the deficiencies of the bioclimatic envelope approach to predicting the potential geographic distribution of a species in a particular climatic scenario, the thirteen researchers satisfied themselves that "estimates of long-distance gene flow based both on direct observations and on genetic methods provide evidence that genes can move over spatial scales larger than habitat shifts predicted under climate change within one generation." In fact, they write that "both theoretical and empirical data suggest that the positive effects of gene flow on adaptation may dominate in many instances."

In light of the results of their various analyses, Kremer et al. conclude that "many tree species have evolved dispersal syndromes enabling the effective flow of genetic information across distant populations inhabiting contrasting environments," and they say that these exchanges "may in the case of forest trees favor adaptation to changing climatic conditions, compensating for their long-generation time." Thus, they propose that researchers in this field should focus on "future experimental and theoretical research that would better integrate dispersal biology with evolutionary quantitative genetics," which efforts they feel would greatly improve predictions of tree responses to climate change.