"Our genetic analysis shows that northern plant populations acquire mutations that disable sex itself, a trait central to the biology of almost all higher organisms," says Queen's biologist Christopher Eckert, co-author of the study and an expert in reproductive evolution.

These findings are provocative because they point to the possibility of rapid reproductive evolution in other species at the northern fringes of their range, Dr. Eckert explains. "This is significant because almost all of the designated species at risk in Canada consist of populations at their northern range limit."

"Rapid reproductive evolution at the range limit will clearly affect decisions about the management of these marginal populations," he continues. "A shift in how plants reproduce will also greatly affect whether or not they will be able to move with changing climates, especially rapid global warming caused by humans."

Focusing on Decodon verticillatus, a dominant shrub in wetlands throughout eastern North America, a series of studies led by Dr. Eckert show that populations switch from being sexual to totally asexual across the northern limit of the species' geographical range. This switch leads to northern populations becoming "enormous, genetically homogeneous superclones."

By comparing reproduction in natural populations versus a benign greenhouse environment, the research team learned that the reproductive switch is due to genetic factors causing sexual sterility.

These sterility mutations can spread in northern populations because the harsher environment makes sex relatively unsuccessful compared to asexual clonal reproduction (where plants make genetically identical offspring by vegetative budding). This is akin to th
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Contact: Nancy Dorrance
dorrance@post.queensu.ca
613-533-2869
Queen's University
15-Nov-2004