Genetics, Vol. 166, 307-329, January 2004, Copyright © 2004
First-Generation Linkage Map of the Gray, Short-Tailed Opossum, Monodelphis domestica, Reveals Genome-Wide Reduction in Female Recombination Rates
Paul B. Samollowa,
Candace M. Kammererb,
Susan M. Mahaneya,
Jennifer L. Schneidera,
Scott J. Westenbergera,
John L. VandeBerga,c, and
Edward S. Robinsona
a Department of Genetics, Southwest Foundation for Biomedical Research, San Antonio, Texas, 78245-0549,
b Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
c Southwest National Primate Research Center, San Antonio, Texas 78245-0549
Corresponding author:
Paul B. Samollow, Southwest Foundation for Biomedical Research, 7620 NW Loop 410, San Antonio, TX 78245-0549., pbs{at}darwin.sfbr.org (E-mail)
Communicating editor: S. P. OTTO
The gray, short-tailed opossum, Monodelphis domestica, is the most extensively used, laboratory-bred marsupial resource for basic biologic and biomedical research worldwide. To enhance the research utility of this species, we are building a linkage map, using both anonymous markers and functional gene loci, that will enable the localization of quantitative trait loci (QTL) and provide comparative information regarding the evolution of mammalian and other vertebrate genomes. The current map is composed of 83 loci distributed among eight autosomal linkage groups and the X chromosome. The autosomal linkage groups appear to encompass a very large portion of the genome, yet span a sex-average distance of only 633.0 cM, making this the most compact linkage map known among vertebrates. Most surprising, the male map is much larger than the female map (884.6 cM vs. 443.1 cM), a pattern contrary to that in eutherian mammals and other vertebrates. The finding of genome-wide reduction in female recombination in M. domestica, coupled with recombination data from two other, distantly related marsupial species, suggests that reduced female recombination might be a widespread metatherian attribute. We discuss possible explanations for reduced female recombination in marsupials as a consequence of the metatherian characteristic of determinate paternal X chromosome inactivation.
