44.4 Thursday, Jan. 5 The evolution of form and function in the greater white–toothed shrew. HERREL, A*; CORNETTE, R; UMR 7179 C.N.R.S/M.N.H.N., Département d'Ecologie et de Gestion de la Biodiversité, 57 rue Cuvier, Case postale 55, 75231, Paris Cedex 5, France.; UMR 7205 C.N.R.S/M.N.H.N., Département Systématique et Evolution, Origine, Structure et Evolution de la Biodiversité (OSEB), plateforme de morphométrie, 45 rue Buffon, 75005 Paris, France. email@example.com
Many small vertebrates on islands grow larger, mature later, lay smaller clutches or litters, and are less sexually dimorphic and aggressive than their mainland relatives. The intensity of this insular syndrome is thought to be linked to the different ecological characteristics of islands compared to the mainland. Here we study the mandible of the greater white toothed shrew, Crocidura russula, on the French Atlantic islands and compare it to individuals from populations on the mainland to quantify potential effects of insularity. We used both traditional and geometric morphometric analyses to quantify differences in size and shape between populations. Moreover, we describe shape co-variation in skull and mandible shape using 3D surface geometric morphometric tools. Finally, we explore the functional consequences of shape co-variation in skull and mandible using both modelling approaches and in vivo bite force measurements. Our data show that whereas specimens from island populations are not different from adjacent continental populations in mandible size, they are clearly different from continental populations by their shape. Among islands, the shape of the mandible shows various types that can be linked with both the distance from the coast and island surface area. The co-variation between the skull and mandible in C. russula is dominated by the variation in attachment sites of the temporalis muscle which has clear and significant effects on the mechanics of biting.