A grant has been awarded to Dr. Ronald Adkins at the University of Tennessee to work in collaboration with Dr. Scott Steppan of Florida State University to study the evolutionary relationships of the largest family of mammals (Muridae) which includes the common mouse and rat. Although Muridae includes one fourth of all mammals and has immense importance to agriculture, disease, and biomedical research, the relationships among these species distributed throughout the world are extremely unclear. Drs. Adkins and Steppan are sequencing DNA from several genes from a large number of species in this group. Based on computer analysis of the patterns of mutation among the species, the evolutionary tree of Muridae will be reconstructed. The laboratory mouse and rat are the premier research models for human disease and will soon have their entire genomes sequenced. Additionally, serious diseases, such as plague and hantavirus, are spread by parasites harbored by some members of Muridae. Rats, mice and their relatives are also major agricultural consumers and under certain conditions can account for over half of the plant material eaten by herbivores. Significantly, the worldwide distribution of Muridae grants them a unique role in understanding the climatological, geological, and ecological changes that have shaped the world. Having the evolutionary tree of these species will clarify the large-scale genomic changes that distinguish rodents from other mammals (including humans) and will greatly facilitate our understanding of their roles as biomedical models, disease vectors, engines of ecological change, and will allow us to reconstruct the history of this group in the context of ancient geological and climatological events.
