As a plant species spreads from its original environment, the finely tuned genetic advantages that it gained through natural selection on its home turf may not serve individual plants that colonize the edges of the species’ range. That’s especially true if the expansion of the range colonizes very different habitat.
Judy L. Stone, associate professor of biology, recently received a $306,632 grant from the National Science Foundation to study “Gene flow, selection, and maintenance of mating-system diversity on an ecological gradient” by studying plants in Costa Rica. She and a company of research assistants (24 research experiences over the four-year life of the grant) including mostly Colby students will compare plant specimens in the warm, sunny, coastal zone of Costa Rica with examples of the same species that live close by but in cloudy, rainy, cool, mountain zones.
The exchange of genes between the habitats results from birds carrying seeds from one to the other. The research addresses what Stone calls “a classical question” in her field, evolutionary genetics: “How is gene flow counteracting natural selection?” In other words, how are the genes fine-tuned for a warm, coastal zone counteracting natural selection taking place in the cool, mountain climate?
To do so she and her assistants will grow replicate gardens in both locations, with plants from both zones side-by-side in both places. That will show if either population exhibits a “home field advantage.” Molecular genetic analysis that uses a type of DNA fingerprint will all be done in labs at Colby, Stone said.
A related study that is part of the project will compare various, separate populations of plants up and down the coast, both in coastal and mountainous regions. That’s the adventurous part of the study, Stone said, and she tries to take students along whenever possible.
The project will entail trips to Costa Rica each summer and each January for the next few years. Dates on the NSF grant are from March 2009 through July 2013.