Drs. Scott Steppan (Florida State University) and Ronald Adkins (University of Tennessee Health Science Center) have received a grant to study the evolutionary relationships of the most diverse family of mammals (Muroidea) that includes the common mouse, rat, and hamster. Although Muroidea includes one fourth of all mammals and has enormous importance to agriculture, disease, and biomedical research, the relationships among these worldwide species are extremely unclear. They will reconstruct the evolutionary family tree of Muroidea using computer analysis of DNA sequences for many genes from over 270 species. The laboratory mouse and rat are the premier research models for human disease and have had their complete genomes sequenced. Additionally, members of Muroidea harbor many human diseases, such as plague and hantavirus, and can account for over half of the agricultural losses due to herbivores. Significantly, the worldwide distribution of Muroidea grants them a unique role in understanding the climatological, geological, and ecological changes that have shaped the world. 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 and disease vectors, and will help determine how geological and climatological events contribute to the evolutionary process.
