Genetics of reproductive isolation and sex determination in allopolyploid clawed frogs (xenopus)

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Of interest to geneticists is the identity and impact of genes that cause reproductive incompatibilities. Another important molecular genetic question asks how polyploid organisms maintain crucial phenotypes, such as sex determination, in the wake of complete genome duplication. The proposed research will employ polyploid clawed frogs (Xenopus) to investigate the abundance and effect of genes involved with reproductive incompatibilities and also to narrow down the genetic region that determines their sex. We will utilize the considerable technical resources available for this group, including a complete genome sequence, expressed sequence tag databases, and prefabricated microarray chips. We will also utilize and explore natural characteristics that make these frogs amenable to genetic inquiry, including the production of viable hybrids and backcrosses, and differential expression of paralogs formed by polyploidization. Our specific goals are to (a) use phenotype association mapping to further narrow down the sex determining region of clawed frogs, (b) quantify the number and effect of genes that cause reproductive incompatibilities between species, and (c) test for a correlation between expression divergence and fertility of backcross hybrids. Results of this work will have implications for our understanding of gene and genome duplication - fundamental genetic processes that occurred throughout the tree of life including in human ancestors. This research will also identify genes with male-biased expression, elucidate the genetic basis of reproductive incompatibilities between species, and provide a genomic framework for study of sex determination after genome duplication. This work will train graduate and undergraduate students at McMaster in NSERC priority areas including molecular genetics, functional genomics, bioinformatics, and computational biology.