These lectures are designed as updates to topics covered in biology textbooks from the 1960s-80s. Each month is dedicated to a different subject: mimicry; kin selection (a form of natural selection); and DNA/the organization of the genome. The course examines how recent research has changed our understanding of evolution.
March 3/Mimicry: The publication of On the Origin of Species moved mimicry from a novelty mainly of interest to butterfly collectors, into a powerful example of natural selection in action. Types of mimicry were named – Batesian, Mullerian, Mertensian, Aggressive – and were contrasted. More recent research has revealed enough overlap in these “types” to indicate a need for a more unified theory. In addition, our current appreciation of animals’ diverse sensory capacities suggests that mimetic similarities may have evolved in other sensory dimensions. A few examples are known of insects mimicking the pheromones of other species, but this phenomenon may be far more common. In parallel, auditory mimicry was mainly studied in birds, but with notably less success in identifying the selective forces involved.
April 7/Kin selection: Aristotle was very interested in honeybees and social wasps. He was puzzled by the behavior of workers laboring to assist in the feeding and care of offspring that were not their own. Two thousand years later Charles Darwin also puzzled over another formulation of the same question: How does altruistic behavior evolve? In 1963 W.D. Hamilton published the mathematical formula and rationale that was named “kin selection,” at long last providing a plausible answer to this long-standing question. The essence is that if altruistic behavior has a genetic basis, being altruistic towards close family members can cause these genes to increase, even if the altruists have fewer offspring themselves. Kin selection seemed to solve this evolutionary conundrum and quickly became popular. However, more recent research indicates other explanations may be needed to explain the evolution of much apparent altruistic behavior. Excessive reliance on kin selection has short-circuited research on alternative explanations for apparent altruism.
May 5/DNA and the organization of the genome: The genome is the total of the DNA included in an organism’s cells. By the middle of the 20th century, it was widely acknowledged that DNA provided the molecular basis of inheritance. It was shown to be organized into chromosomes, and these replicated and assorted themselves before cells divided. In 1952 Watson and Crick (and Franklin) elucidated the structure of DNA and how it could carry the genetic code for assembling proteins. Two decades later molecular geneticists realized that only 10% or so of the genome coded for proteins. Since then, they have been working to determine the multiple functions of the remainder. The picture presented a generation ago needs a major update.
Wayne Hoffman is trained as a behavioral ecologist and has worked on seabird biology; marine mammal and sea turtle distribution and ecology; forest bird habitat and behavior; and the value of forests and forest plantations.
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