Morphological integration and modularity in the rodent skull
Support: National Science Foundation (Doctoral Dissertation Improvement Grant IOS 0407570)
For my Ph.D. dissertation, I fitted a large number of alternative models of modularity/local integration to datasets consisting on skulls of ecologically divergent species of rodents, with the purpose of finding the modules that best account for the co-variation structure in each dataset. Analyses based on landmark-bound modules suggest that even though ecologically divergent but closely related rodent species support quite different models of modularity, the developmental modules of the mandible (i.e., the regions that map to the mesenchymal condensations from which mandibles are initially assembled) seem to be embedded in most of these species' covariation structures. The presence of conserved developmental modules suggests that within-species traits may group into "super-modules" comprised by or derived from phylogenetically persistent modules, a pattern that suggests intriguing possibilities regarding how developmental constraints may influence the evolvability of complex, modular systems.
Currently, I am in the process of recasting my dissertation analyses in terms of the local measurements of shape variation proposed in Marquez et al (2012).
Márquez, E.J. 2008. Software MINT: Modularity and Integration analysis tool for morphometric data. University of Michigan, Ann Arbor. [ DOWNLOAD Win32 Win64 ]
Márquez, E.J. 2009. A General Framework for Inferring the Developmental Causes of Modularity of Morphological Variation with Applications to the Craniomandibular Complex in Morphological Variation with Applications to the Craniomandibular Complex in Rodents. Ph.D. Dissertation, University of Michigan, Ann Arbor. [ UMICH ]
| Models of modularity with most support in two closely related rodent species. |
