Plant & Animal Genome V Conference
Town & Country Hotel, San Diego, CA, January 12-16, 1997.
PAG-V: S24 - MAMMALIAN EVOLUTION - A ROO-VIEW
S24
MAMMALIAN EVOLUTION - A ROO-VIEW
GRAVES, JENNIFER A. MARSHALL
School of Genetics, Latrobe University, Melbourne, Vic 3083, Australia
All three mammal groups have similar DNA and gene contents but show major variations in genome organization. Rules established
by studies in human and mouse do not always apply to marsupials and monotremes, and we must make new and more general laws. For
instance: Sex differences in marsupial recombination rates favour males rather than females. Comparative gene mapping suggests that mice,
not marsupials, break more general rules of vertebrate genome conservation. Comparative mapping of sex chromosomes in all three mammal
groups defines a smaller ancestral X and Y, and three regions recently added to the eutherian X and Y. The mammalian Y is monophyletic, so
the tiny marsupial Y is a good mammalian model. A 'marsupial test' can be used to assess candidate sex determining and spermatogenesis
genes. Thus it is not always the marsupials and monotremes (usually considered weird mammals) that are exceptional. Often, the weird
mammals are humans, and particularly mouse, which break more general mammalian, or even vertebrate rules. J.A.M. Graves (1996). Ann.
Rev. Genet. (in press).