Higher CO2 could change plant evolution

Feb. 16, 2011 at 6:28 PM
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ANN ARBOR, Mich., Feb. 16 (UPI) -- Higher carbon dioxide levels brought on by global warming may alter plant evolution, research by University of Michigan scientists indicates.

The research suggests rising CO2 levels could affect interactions between plants and the bugs that eat them, the university said in a news release Wednesday.

The study focused on the effect elevated carbon dioxide had on common milkweed, one of many plants that produce toxic or bitter chemical compounds to protect itself from being eaten by insects, researchers say. The chemical defenses result from a history of interactions between the plants and insects, such as monarch caterpillars, that feed on them.

Researchers Rachel Vannette and Mark Hunter investigated whether different genetic strains of the milkweed from a single population source in Northern Michigan would respond differently to increasing atmospheric carbon dioxide levels and if so, how the responses could affect the plants' chances of being eaten.

While all plants grew larger in response to elevated carbon dioxide, plant families responded differently to higher carbon dioxide in production of chemical and physical defenses against plant-eating insects, the researchers say.

Vannette said investigators don't know what the changes in defenses means for the monarch butterfly, "but that's a question we're investigating."

The findings are in the March issue of Global Change Biology.

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