WASSERSUG, R.J.: Problems in Metamorphosis Above the Molecular Level

Tadpoles from a single clutch, which hatch at approximately equal size, can vary in size by nearly an order of magnitude by the time they metamorphose. This observation has led to extensive research by ecologists on social and environmental factors that influence metamorphosis. Independently, molecular biologists have made great strides in understanding genetic programs in tadpole tissues that are activated when metamorphosis begins. What has been largely missing in our efforts to understand metamorphosis are the mechanistic links between the factors studied by ecologists and the genes studied by molecular biologists. We do not understand, for example, how extrinsic factors, such as density or water depth, are sensed by amphibian larvae and ultimately manifested as changes in gene transcription within specific tissues. In my talk I will review some of the environmental factors that influence size at metamorphosis by influencing growth. I will then present a set of heuristic models that explore the balance between growth and metamorphosis at the tissue level, in an effort to develop testable hypotheses about the link between the environmental and molecular regulation of metamorphosis.