Skeletogenesis and sequence heterochrony in rodent evolution, with particular emphasis on the African striped mouse, Rhabdomys pumilio (Mammalia)

LAURA A. B. WILSON; CARSTEN SCHRADIN; CHRISTIAN MITGUTSCH; FERNANDO C. GALLIARI; ANDREA MESS; MARCELO R. SÁNCHEZ-VILLAGRA

ORGANISMS DIVERSITY & EVOLUTION

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2010 vol. 10 p. 243 - 258

1439-6092

Data documenting skeletal development inrodents, the most species-rich ?order? of mammals, are atpresent restricted to a few model species, a shortcomingthat hinders exploration of the morphological and ecologicaldiversification of the group. In this study we providethe most comprehensive sampling of rodent ossificationsequences to date, with the aim of exploring whetherheterochrony is ubiquitous in rodent evolution at the onsetof skeletal formation. The onset of ossification in 17 cranialelements and 24 postcranial elements was examined foreight muroid and caviomorph rodent species. New data areprovided for two non-model species. For one of these, theAfrican striped mouse, Rhabdomys pumilio, sampling wasextended by studying 53 autopodial elements and examiningintraspecific variation. The Parsimov method ofstudying sequence heterochrony was used to explore therole that changes in developmental timing play in earlyskeletal formation. Few heterochronies were found todiagnose the muroid and caviomorph clades, suggestingconserved patterning in skeletal development. Mechanismsleading to the generation of the wide range of morphologicaldiversity encapsulated within Rodentia may be restrictedto later periods in development than those studied in thiswork. Documentation of skeletogenesis in Rhabdomysindicates that intraspecifc variation in ossification sequencepattern is present, though not extensive. Our study suggeststhat sequence heterochrony is neither pivotal nor prevalentduring early skeletal formation in rodents.