Sunday, August 21, 2011

Observing Evolution

Can we see evolution in action? The New York Times reports that a group of evolutionary biologists and geneticists from Harvard University is attempting to find the mechanisms that lead to physical changes and learn how those changes affect fitness. They also want to learn how changes make an organism likely to survive and reproduce. These are critical issues for honey bee health. Harvard’s Dr. Hopi Hoekstra explains, “Fitness is the most important concept in biology, but no one ever measures it.” To observe evolution while it occurs, the researchers devised a test of fitness. They built four large enclosures on light-colored, sandy soil to house deer mice. A distance away, they built another four similar enclosures on dark-colored soil. Some of the deer mice, North America’s most populous mammal, have lighter colored fur than typical deer mice. The researchers discovered that the range of colors is dependent upon a single gene that controls pigment-producing cells. Mutations in this gene lead to deer mice with various levels of fur color. Mice that differ greatly in color from their background are easily spotted by predators, quickly changing the population of highly visible mice. The researchers are measuring the fur color shift in deer mice populations. The deer mice study can be viewed at

While people often think of evolution as an extremely gradual process, at times rapid changes occur. This is seen with pathogens becoming antibiotic resistant and honey bee parasitic mites quickly becoming resistant to chemical treatments. Hopefully, we will start seeing honey bee populations evolve that are fit to live in our rapidly changing environment. European honey bees have been in the presence of parasitic Varroa mites for about 150 years. In this time some resistant lines of honey bees survived, and their offspring are now being selected by breeders. Today’s photo shows tickseed coreopsis, a colorful summertime carpet along roadsides and clearings. Coreopsis is a member of the important family of bee plants, the composites, or sunflowers.

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