Growth trajectories in the cave bear and its extant relatives: an examination of ontogenetic patterns in phylogeny

BMC Evolutionary Biology

Research Article

Madlen Stange¹  Marcelo R. Sánchez-Villagra¹  Madeleine Geiger¹  Manuela Fuchs¹ 

[1] Palaeontological Institute and Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006, Zürich, Switzerland;

关键词: Mammalia;    Ursus;    Ontogeny;    Variation;    Disparity;    Evolution;    Morphometrics;    Cranium;    Mandible;   

DOI  :  10.1186/s12862-015-0521-z

 received in 2015-04-29, accepted in 2015-10-27,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundThe study of postnatal ontogeny can provide insights into evolution by offering an understanding of how growth trajectories have evolved resulting in adult morphological disparity. The Ursus lineage is a good subject for studying cranial and mandibular shape and size variation in relation to postnatal ontogeny and phylogeny because it is at the same time not diverse but the species exhibit different feeding ecologies. Cranial and mandibular shapes of Ursus arctos (brown bear), U. maritimus (polar bear), U. americanus (American black bear), and the extinct U. spelaeus (cave bear) were examined, using a three-dimensional geometric morphometric approach. Additionally, ontogenetic series of crania and mandibles of U. arctos and U. spelaeus ranging from newborns to senile age were sampled.ResultsThe distribution of specimens in morphospace allowed to distinguish species and age classes and the ontogenetic trajectories U. arctos and U. spelaeus were found to be more similar than expected by chance. Cranial shape changes during ontogeny are largely size related whereas the evolution of cranial shape disparity in this clade appears to be more influenced by dietary adaptation than by size and phylogeny. The different feeding ecologies are reflected in different cranial and mandibular shapes among species.ConclusionsThe cranial and mandibular shape disparity in the Ursus lineage appears to be more influenced by adaptation to diet than by size or phylogeny. In contrast, the cranial and mandibular shape changes during postnatal ontogeny in U. arctos and U. spelaeus are probably largely size related. The patterns of morphospace occupation of the cranium and the mandible in adults and through ontogeny are different.

【 授权许可】

CC BY   
© Fuchs et al. 2015