Springer Science+Business Media B.V. 2010. Linkage maps provide information not only on the linear order of genetic loci on chromosomes; they also reveal the locations and frequencies of crossover events during gametogenesis. As such they have been invaluable resources for genetic mapping for nearly 100 years and continue to be extremely useful for providing insight into the meiotic process and disruptions thereof that physical mapping strategies cannot furnish. Linkage mapping research with marsupial mammals had a late inception due to a long-standing lack of animal resources amenable to the reliable, multigenerational breeding programs necessary for the establishment of genetic lines and tools required for linkage-mapping studies. As this impediment was overcome through the establishment of several self-perpetuating marsupial breeding colonies late in the twentieth century, linkage mapping studies began to uncover evidence of unexpectedly low rates and unusual sex-specific patterns of recombination that run counter to those observed for almost all other vertebrates examined. This chapter describes the history of linkage research in marsupials, summarizes the linkage maps of the tammar wallaby and the gray, short-tailed opossum, considers the value of these linkage maps in connection with the recent opossum and wallaby genome projects, and discusses the extent and implications of low recombination rates and sex-specific recombination differences in these species. The chapter ends with speculation on the potential of the opossum as a model for recombination research.
