Scientists assess effects on suburbanization on plant evolution
A team of researchers, including two scientists from the College of Natural Resources and the Environment, has received a three-year, $450,000 grant from the National Science Foundation to determine whether suburban development can affect the evolution of a native plant by changing how it interacts with insects.
“Suburbanization affects how plants and animals interact with each other, and it seems reasonable to assume that this could influence how species evolve,” says Lynn Adler, assistant professor of Entomology. The other researchers are Paige Warren, assistant professor of Natural Resources Conservation, and Rebecca Irwin of Dartmouth College in New Hampshire.
Their research will focus on yellow jasmine, a common resident of open woodlands in the southeastern United States that defends itself from hungry bees and caterpillars by producing a toxin. Yellow jasmine has responded well to urbanization, moving from woodlands into open areas and sunny gardens, where it is exposed to more insect activity. Unfortunately, some of the species that are predators of the plant are also thriving.
Yellow jasmine is visited by carpenter bees that rob the plant of nectar by puncturing the blossoms, and a caterpillar that eats the flowers. Pilot data from several sites in the Raleigh, N.C. area have already shown that yellow jasmine growing in open areas has to endure twice the attention from these insects, since humans conveniently provide some of the essentials they need to live.
“We provide food in the form of garden flowers and water, and some insects, especially the carpenter bee, get along well with humans and enjoy living in the siding of wood houses,” says Warren, an urban ecologist. “This lowers the number of species in a given area, but increases the population of the species that are present.”
Because of the increase in nectar robbing and loss of flowers to caterpillars, Adler and Warren believe that plants with higher toxin levels may have an advantage, and reproduce more successfully in suburban areas compared to forested environments.
Urbanization is also expected to affect how yellow jasmine is pollinated. “Urbanization may cause a rise in bees that visit many different plants, termed generalists,” says Adler. “Greater amounts of pollen will be deposited in yellow jasmine flowers, but much of it may be from foreign sources, which may clog the stigmas and impact reproduction.”
Outreach is an important part of the project, and will include events at the North Carolina Botanical Gardens in Chapel Hill and programs for local garden clubs. “We don’t often realize that simple things like the use of fertilizer and pesticides in gardens or planting exotic plants can have a profound impact on native species, but evolution and natural selection are happening in our back yards,” says Warren.
April 4, 2008.
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