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Show Faculty Sponsor Dr. Wayne Potts "FUNCTIONALLY EQUIVALENT HOX TRANSLOCATION SHOWS STRONG FITNESS DEFECT IN "NATURE' Leda Ramoz, (Dr. Wayne Potts) Department of Biology, University of Utah A great surprise of the genomic era is that many genes when disrupted produce no phenotypic change. Numerous examples involve the highly conserved Hox genes, which are transcription regulators of early development. Translocation of the Hoxd3 al- lele into the Hoxa3 locus reveals no phenotype despite 50% pro-tein sequence difference. This has been interpreted as functional redundancy. Alternatively, phenotypes might be ecologically de-pendent thus, their effects are invisible in the laboratory. To test this hypothesis we bred the Hoxa3D3 translocation homozygotes to wild mice and used the F2 offspring as founders of semi-natu-ral populations. Genotyping the first 1246 offspring has revealed a 47% deficiency of Hoxa3D3 homozygotes, a 39% deficiency of a3D3/wild heterozygotes and a 29% deficiency of the Hoxa3D3 allele relative to expected frequencies (p<0.0001), indicating this mutant has a massive impact on adult fitness. Much of this defect is due to wild type males being five times more likely to gain ter-ritories (p<0.005) because territorial males do most of the breed-ing. These findings suggest that Hoxa3 and Hoxd3 alleles are not functionally equivalent and that this ecological functional genom- ics approach is a valuable method for determining functions of genes that have no apparent phenotype under laboratory condi- tions. |