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Show posters on the hill Does Experimental Removal of Sexual Selection Effect Offspring Quality? Adam Nelson, Wayne K. Potts Department of Biology I n 1871 Darwin formulated the theory of Sexual Selection, recognizing that competition over mates results in differential reproductive success and is therefore a fundamental source of evolution. Although an intuitive theory of its purpose is to produce high quality offspring, this idea remains poorly understood. One particular challenge has been to determine how the mechanisms of sexual selection-inter-sexual and intrasex-ual conflict-effect offspring quality. One recent set of studies demonstrates fitness benefits in offspring viability due to inter-sexual selection (mate choice, usually by females, that selects for attractive traits in the opposite sex). When either male or female mice were allowed to choose a mate from an isolated group, they recognized traits in the preferred mate that led to greater offspring viability.Miss-ing from these experiments, however, was information that is important in normal social and ecological conditions, namely, intra-sexual selection (contests, usually between males, that select for traits of dominance and endurance). Using genetic techniques and a phenotron (a biological facility resembling a natural environment), we are conducting an experiment to discern the in Does Experimental Removal of Sexual Selection Effect Offspring Quality? Adam Nelson, Wayne K. Potts Department of Biology when information retiardinu both inter-lablc. as is ihc ca^c in nature? Tii-naiurai environment to delect small differenc lab showed that inbred mates (dark line) had significantly lower ivorship than outbred males (tight line). This difference was f« greater than results from standard lab Female male choice (inter-sexual selection) in mice. Females allowed to choose their mate produce sltghlK but consistently better offspring. are compel in j: a >e\uall> -selected. semt-n;iuir;il lineag lected, random!) c:ii2c bred lineage to see who i petitor-and to find the net biological effect of vivo effects of intra- and intersex-ual selection on offspring quality in mice. We have raised a "sexually selected" lineage in the phenotron and a "control" lineage in the laboratory, where mice were randomly cagebred. At present we have pitted subsets of each lineage against each other in the phenotron. These mice were selected based on specific genetic markers and their Major Histocom-patibility Complex (MHC) hap-lotype-a genetic locus previously shown by our laboratory to influence mating behavior in mammals. We will soon determine the following. What group was more suc- cessful in reproduction, and what was the major mechanism of their reproduction: inter- or intra-sexual selection. This novel experiment seeks to understand how inter-sexual selection (based on MHC mating preferences) and intra-sexual selection (based on territorially of male mice) interact to effect offspring viability in a mammalian system. It also sheds light on how breeding environments (natural vs. laboratory) might effect genetic quality of organisms. |
