Differentiation of craniomandibular morphology in two sympatric Peromyscus mice (Cricetidae: Rodentia)
In the Santa Cruz Mountains of California, dietary partitioning is believed to allow Peromyscus californicus (California mouse) and Peromyscus truei (pinyon mouse) to occur sympatrically; P. californicus feeds primarily on arthropods, whereas P. truei feeds primarily on acorns. To better understand how these species partition resources, we examine if these dietary differences extend to differences in craniomandibular morphology. We use a geometric morphometric approach to test the hypothesis that P. californicus and P. truei exhibited size and shape differences in craniomandibular morphology, in particular, regions of the skulls that pertain to biting ability and mechanical advantage of the jaw adductor muscles. We found that P. truei exhibited relatively wider zygomatic arches, relatively broader, more robust masseteric fossa and coronoid process, and a higher mechanical advantage of the masseter jaw muscle. These craniomandibular traits suggested that P. truei exhibits a relatively stronger bite force that is more suitable to access hard-shelled acorns despite its smaller body size.
KeywordsBite force Dietary partitioning Geometric morphometrics Mechanical advantage Skull morphology
We thank the many mentors, staff, and students of the University of California, Santa Cruz (UCSC) Small Mammal Undergraduate Research in the Forest (SMURF) program who have worked with us and taught us about the natural history of deer mice. We would like to thank Tina Cheng (UCSC), Karen Holl (UCSC), and Gage H. Dayton (UCSC) for their support of this study.
Funding for the SMURF program was provided by the UCSC Department of Ecology and Evolutionary Biology, the Webster Chair Fund, the Kenneth S. Norris Center for Natural History, and the UC Natural Reserve System. CJL was funded by a National Science Foundation Graduate Research Fellowship.
- Anderson MJ (2001) A new method for non-parametric multivariate analysis of variance. Austral Ecol 26:32–46Google Scholar
- Goodall C (1991) Procrustes methods in the statistical analysis of shape. J R Stat Soc Ser B Stat Methodol 53:285–339Google Scholar
- Kardong KV (2014) Vertebrates: comparative anatomy, function, evolution Boston: McGraw-Hill EducationGoogle Scholar
- Kaufman DW, Kaufman GA (1989) Population biology. In: Kirkland G, Layne J (Eds) Advances in the study of Peromyscus Rodentia. Lubbock, pp 233–271Google Scholar
- R Core Team (2017) R: A language and environment for statistical computingGoogle Scholar
- Rohlf FJ (2005) TpsDig, digitize landmarks and outlines, version 25 Department of Ecology and Evolution, State University of New York at Stony Brook New York, USA, Available at: http://life.bio.sunysb.edu/ee/rohlf/software.html
- Schlager S (2016) Morpho: calculations and visualisations related to Geometric Morphometrics R-package version 24Google Scholar
- Tanner JB, Zelditch ML, Lundrigan BL (2010) Ontogenetic change in skull morphology and mechanical advantage in the spotted hyena (Crocuta crocuta). J Morpho 271:353–365Google Scholar
- Turnbull WD (1970) Mammalian masticatory apparatus Field Museum of Natural HistoryGoogle Scholar
- Žagar A, Carretero MA, Vrezec A, Drašler K, Kaliontzopoulou A (2017) Towards a functional understanding of species coexistence: ecomorphological variation in relation to whole-organism performance in two sympatric lizards. Funct Ecol 211:1336–1312Google Scholar
- Zelditch ML, Swiderski DL, Sheets HD (2012) Geometric morphometrics for biologists: a primer Academic PressGoogle Scholar