CRYPTIC SPECIES IN SIGMODON HISPIDUS : EVIDENCE FROM DNA SEQUENCES

Phylogenetic relationships among 8 subspecies of Sigmodon hispidus from North, Central, and South America were examined using DNA-sequence data from the mitochondrial cytochrome-b gene. The magnitude of DNA-sequence variation detected among these subspecies, in some cases, exceeded levels of interspecific variation observed among currently recognized species of Sigmodon. These data suggest that S. hispidus is paraphyletic and that a minimum of 3 species exist within the currently recognized taxon. Consequently, the taxonomy should be revised to recognize the following samples as distinct species: those from the United States and north-central Mexico, those from southern Mexico, and those from Central and South America.