A New model System to Test the Adaptive Significance of Recombination

点击翻译按钮获取中文摘要

Rice9806917 Reproduction in plants and animals can occur with or without genetic recombination, yet most multicellular organisms utilize genetic recombination when producing offspring. In contrast, many agriculturally important crops such as nut trees, fruit trees, grapes, berries, etc. are propagated clonally, i.e., without genetic recombination. What are the costs of bypassing the normal recombining mode of sexual reproduction? The proposed research creates a new model system that permits a truly definitive test of most of the current theories concerning the adaptive significance of genetic recombination. The model system will be used to test the hypothesis that new beneficial mutations are incorporated into recombining populations at a far greater rate than clonal populations. The capacity for rapid adaptive evolution is becoming increasingly important owing to the rapid environmental change induced by human activities, e.g. global warming, habitat fragmentation, introduction of exotic species and disease organisms. The common fruit fly (Drosophila melanogaster) is used as a model system owing to its inexpensive culturing, short generation time, and availability of numerous genetic tools which are critical for the operation of these multi-generation experiments. Using a new clone-generator technology recently developed in our laboratory, we will experimentally introduce new beneficial mutations into populations with low vs. high levels of genetic recombination. Next we will measure the probability of accumulation of these beneficial mutations and relate this to the experimentally controlled level of genetic recombination. Current theory predicts that genetic recombination will greatly enhance the capacity of the populations to incorporate new beneficial mutations, and to purge deleterious mutations. Results from these experiments will contribute to our basic understanding of plant and animal breeding programs, long and short-term evolution, and will help us to predict the capacity of different life forms to adapt to human-induced environmental change.