Physical and Comparative Gene Maps in Marsupials

Comparative gene mapping in marsupials is responsible for many advances in our understanding of the events occurring during mammalian genome evolution. Over the past few years, the ease and speed at which genes can be physically mapped in marsupials has resulted in moderately dense physical maps for the South American opossum and the tammar wallaby. These maps have enabled genome sequence assemblies to be anchored to chromosomes and facilitated detailed comparative studies into genome evolution. The physical assignment of genes to marsupial chromosomes has resulted in many interesting and unexpected findings, including the discovery of novel genes and the absence of others, as well as providing insight into the evolution of epigenetic phenomena of genomic imprinting and X chromosome inactivation. Expanding comparative maps to include other distantly related marsupials is now possible and will be important for an accurate reconstruction of the ancestral marsupial karyotype.