The role of evolutionary integration in the morphological evolution of the skull of caviomorph rodents (Rodentia: Hystricomorpha)

ALVAREZ, A.; PEREZ, I.; VERZI, D.H.

EVOLUTIONARY BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2015 vol. 42 p. 312 - 327

0071-3260

The mammalian cranium is a complex structure composed by three partially independent modules: face, cranial base and cranial vault. At the same time, it interactswith the mandible by sharing the masticatory function. Since these units develop and work together, their function and evolution may occur through correlated changes. Here, weassessed the patterns of evolutionary shape variation and covariation (i.e. integration) of cranial modules and mandible among the highly ecomorphologically diversecaviomorph rodents, and the potential evolutionary consequences on the morphological evolution of this clade. Three dimensional geometric morphometrics was used to describecranio-mandibular shape. The phylogenetic signal and evolutionary allometric component of morphometric variables were analyzed; in addition, evolutionary covariation amongcranial modules and mandible was assessed using phylogenetic comparative methods. Significant phylogenetic signal and evolutionary allometry were detected. Large covariancevalues, involving coordinated breadth increase as the main shape change, were recorded between cranial vault and base, followed by cranial vault and face, and face and mandible.Since the basicraniummay be the main cranial integrator, the overall widening of the cranial base, derived from the enlargement of the auditory bullae, could be influencing the integrated evolution of skull. In caviomorphs, the craniomandibular morphological evolution would be the outcome of a tight covariation among the modular units, and this could be driven by several factors such as allometry and specializations to environmental niches.