Globin Macromolecular Sequences in Marsupials and Monotremes

We have reviewed published data on haemoglobin and myoglobin DNA and protein sequences from marsupial and monotreme mammals, and drawn attention to the difficulties that have been encountered in using these data to estimate dates of evolutionary divergence. We argue that continuing studies of marsupial and monotreme globins, particularly molecular studies on gene organisation and regulation, are likely to contribute significantly to our understanding of gene and organismal evolution. In this context we suggest that studies on the globin genes of a monotreme and a South American marsupial would be especially rewarding.