Developmental Modularity and the Marsupial-Placental Dichotomy

Goswami, A. and Weisbecker, V. and Sanchez-Villagra, MR (2008) Developmental Modularity and the Marsupial-Placental Dichotomy. Society of Vertebrate Paleontology.

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The contrasting evolutionary histories of marsupial and placental mammals have often been attributed to their different reproductive strategies. The speciose placentals develop mainly in utero and have radiated into diverse niches, whereas marsupials are born in a highly altricial state with immediate functional requirements and are limited in taxonomic, ecological, and morphological diversity. These differences have been tied to heterochrony, and it has been hypothesized that coordinated shifts in developmental timing occur among functionally- or developmentally related structures, such as forelimbs in marsupials. We use new ossification sequence data for 11 marsupial and 14 placental species to assess the integration of first ossification timing among skeletal elements. Although cranial elements fail to demonstrate significant coordination, marsupials and placentals differ markedly in postcranial integration. Marsupials display independent anterior and posterior developmental modules, whereas placentals show significant integration of the entire appendicular skeleton. This developmental integration of the placental postcranium is consistent with a recent study of phenotypic modularity in limbs of placental mammals, showing a potential correspondence between integration of developmental timing and of shape. The observed differences in postcranial integration between marsupials and placentals may reflect the disparate evolutionary histories of these two mammalian clades. J. Exp. Zool. (Mol. Dev. Evol.) 312B:186-195, 2009. (C) 2009 Wiley-Liss, Inc.

Item Type: Other
Additional Information: Abstracts from 68th Annual Meeting of the Society of Vertebrate Paleontology - Supplement to v.28, no.3
Subjects: 04 - Palaeobiology
99 - Other
Divisions: 04 - Palaeobiology
Volume: 312B
Page Range: pp. 186-195
Depositing User: Sarah Humbert
Date Deposited: 19 Aug 2009 10:19
Last Modified: 23 Jul 2013 09:55

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