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 http://www.nytimes.com/2011/08/09/science/09mouse.html.

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.

--Richard

Behavior

One of the purposes the honey bee genome sequencing project was to reveal the complexity of the behavior of honey bees as social insects. It was thought that we might learn from the honey bee some of the ways that behavior evolved in human beings. The results of the project, which was completed in 2006, will be studied for years to come. At the same time that honey bee behavior is being studied, psychologists, evolutionary biologists, and anthropologists are comparing the behavior of humans to our relatives from a common ancestor, the chimpanzees. The researchers describe humans’ “cooperative behavior” as opposed to chimpanzees’ “fierce aggression” as being the difference that shaped human evolution. Those who have kept or studied honey bees are aware of the complex behaviors of the bees, especially involving communication, navigation, guarding the hive, protecting from disease, preventing inbreeding, and preparing for seasonal colony events like replacing the queen, swarming, and storing honey.

I was interrupted from my reading of an interesting New York Times piece on the behavior of humans and chimpanzees, http://www.nytimes.com/2011/03/11/science/11kin.html?_r=2&hpw, when a neighbor came to tell me vandals had damaged one of my outlying bee yards. Someone had deliberately driven a truck into 10 bee hives, leaving several scattered about the ground and others balanced precariously on damaged stands. The exposed hives contained dead bees and dead, chilled brood. Unprotected, stored honey was removed from the exposed hives by robber bees. Small hive beetles, alerted by alarm pheromone from the damaged hives, flew in from great distances to take advantage of the weakened colonies. Honey bees, social insects, protect their hive with their sting. Beekeepers, social creatures as well, protect their hives by watchful neighbors, deputy sheriffs, prosecutors, laws, and jails. Honey bees confine small hive beetles that invade their hives in propolis “jails.” Eventually, the felony vandals will be caught and confined in real jails. I wonder how far our human behavior has evolved. Troglodytes should not be allowed to drive trucks.

--Richard

Honey Bee Evolution

A report published in The New York Times relates that only 28 percent of public high school biology teachers are following teaching recommendations to “describe straightforwardly the evidence for evolution and explain the ways in which it is a unifying theme in all of biology.” Thirteen percent of the biology teachers explicitly advocate creationism, and 60 percent avoid the subject altogether. The Times report: http://www.nytimes.com/2011/02/08/science/08creationism.html?hpw.

A beekeeper tries to explain the complexity of the honey bee’s social behavior in a colony that appears to be as organized as a city full of people. He says that such a well-organized colony can only be the result of creation by a higher being of great intelligence, and he struggles to find bee hive examples of what he calls “intelligent design.” There is wondrous activity among these social insects, but the honey bee colony is certainly not perfect. The colony gathers and produces its own food, increases its numbers and expands its territory. It regulates the temperature and atmosphere of its hive. It can even produce a new queen when one is need. However, there are times when the life cycle of the honey bee colony becomes dead-ended. When dealing with a poorly mated queen, an egg-laying worker, or a queen failing to lay fertile eggs, a colony often becomes hopelessly queenless and then dwindles and dies. Rather than the product of an “intelligent design,” today’s honey bee colony can be better understood as the result of millions of years of evolution in a changing environment. Those colonies that inherited traits, altered by mutations, that make them more survivable in the present environment pass along those traits to their offspring. They replace other less suited colonies that either die or are less successful in reproducing. The replacement of less suited species has been seen recently in the evolution of antibiotic-resistant strains of tuberculosis, insecticide-resistant bed bugs, herbicide-resistant Palmer pigweed, and Varroa mites resistant to the miticides used by beekeepers. Today’s photo: beekeeper Richard Underhill.

--Richard