Meeting Abstract

P1-62   -   Multivariate analyses of cranial morphology inform the taxonomy and evolution of geomyoid rodents. Noftz, LA*; Calede, JM; The Ohio State University at Marion; The Ohio State University at Marion noftz.8@osu.edu

Morphological analyses are critical to quantify variation within and across species, identify taxa, understand species relationships, and shed light on evolutionary patterns. This work is particularly important in groups that display great morphological disparity. Such is the case in geomyoid rodents, a group that includes two of the most species-rich families of rodents in North America: the Geomyidae (pocket gophers) and the Heteromyidae (kangaroo rats, pocket mice, and their relatives). We assessed the differences in skull morphology (including both shape and size) among geomyoids to test the hypothesis that there are statistically significant differences in cranial measurements at the family, genus, and species-levels. Our sample includes a total of 872 specimens, 392 geomyids representing all seven genera and 17 species, as well as 480 heteromyids representing all five genera and 22 species. We used the geometric mean of all specimens in the dataset to compare size across taxa. We also used 14 measurements of the skull and lower jaw normalized for size and multivariate statistical methods to compare shape among taxa at the species, genus, and family levels. Our results show that cranial measurements enable the distinction of geomyoids at the family, genus, and species levels. There is a larger amount of size variation within Geomyidae than within Heteromyidae. Our phylomorphospace analysis shows that the shape of the common ancestor of Heteromyidae and Geomyidae was more similar to the common ancestor of heteromyids than that of geomyids. Allometric patterns within geomyids show negative allometry, at both axes of variation. Within heteromyids, an interesting pattern emerges wherein dipodomyines and non-dipodomyines show significantly different allometric relationships.