PARENT SESSION
Oral Session # 57: Evolutionary Ecology II: Animal.
Presiding: S Juliano
Wednesday, August 6. 1:30 PM to 5:00 PM, SITCC Meeting Room 201.
Morphological divergence in populations of the plains pocket mouse Perognathus flavescens in adjacent habitats.
Wolf, Mosheh*,1, Salazar-Bravo, Jorge2, Frggens, Mike3, 1 University of Illinois, Urbana-Champaign, Illinois2 Texas Tech, Lubbock, Texas3 University of New Mexico, Albuquerque, New Mexico
ABSTRACT- Speciation has historically been thought to occur mostly in isolated populations; however, a number of recent studies of tropical birds and reptiles have shown that morphological divergence and speciation may occur in adjacent habitats, supporting a model of parapatric speciation. Small mammal species may also show morphological divergence and speciation in adjacent habitats, because of the scale of their home ranges and movements. To test this, we studied a common heteromyid rodent, Perognathus flavescens, in two adjacent habitats within the Sevilleta LTER site in central New Mexico: plains sand scrub (PSS), and chihuahuan desert scrub (CDS). We tested the hypotheses that morphological differences exist between adult populations of this rodent in these habitats. We found morphological differences on a number of levels. Mice from the PSS site had significantly larger ears, tails, and feet than mice from CDS. We also observed differences in sexual dimorphism between sites. Males from CDS had larger ears and tails than females, while no such difference was observed in PSS. Mice from the CDS site also showed sexual dimorphism in allometry: females showed correlations between body length and foot, tail, and ear lengths, while males did not. In contrast, in mice from the PSS site these allometric measurements did not differ between sexes. These morphological differences occur in populations separated by less than 5 km, separated by no major barriers, and are most likely related to habitat differences alone, because external variables, such as precipitation, temperature, or exposure cannot be invoked as determinant factors. We are in the process of investigating differences in the genetic make-up of these populations; however, preliminary findings indicate that parapatric speciation may be as pervasive in small desert rodents as it is in tropical birds and reptiles.
Key words: morphological divergence, parapatric speciation, Perognathus flavescens