title: Ecogeographical Variation in Skull Shape of South-American Canids: Abiotic or Biotic Processes?
abstract: Species morphological changes can be mutually influenced by environmental or biotic factors, such as competition. South American canids represent a quite recent radiation of taxa that evolved forms very disparate in phenotype, ecology and behaviour. Today, in the central part of South America there is one dominant large species (the maned wolf,Chrysocyon brachyurus) that directly influence sympatric smaller taxa via interspecific killing. Further south, three species of similar sized foxes (Lycalopexspp.) share the same habitats. Such unique combination of taxa and geographic distribution makes South American dogs an ideal group to test for the simultaneous impact of climate and competition on phenotypic variation. Using geometric morphometrics, we quantified skull size and shape of 431 specimens belonging to the eight extant South American canid species:Atelocynus microtis,Cerdocyon thous,Ch. brachyurus,Lycalopex culpaeus,L. griseus,L. gymnocercus,L. vetulusandSpeothos venaticus. South American canids are significantly different in both skull size and shape. The hypercarnivorous bush dog is mostly distinct in shape from all the other taxa while a degree of overlap in shape-but not size-occurs between species of the genusLycalopex. Both climate and competition impacts interspecific morphological variation. We identified climatic adaptations as the main driving force of diversification for the South American canids. Competition has a lower degree of impact on their skull morphology although it might have played a role in the past, when canid community was richer in morphotypes.
authors.affiliation: Programa de Pós-Graduação em Biodiversidade Animal, CCNE, Federal University of Santa Maria, Santa Maria, RS 97110-970 Brazil.
authors.forename: Jamile
authors.initials: J
authors.lastname: de Moura Bubadué
authors.affiliation: Department of Ecology and Evolution, CCNE, Federal University of Santa Maria, Santa Maria, RS 97110-970 Brazil.
authors.forename: Nilton
authors.initials: N
authors.lastname: Cáceres
authors.affiliation: Department of Ecology and Evolution, CCNE, Federal University of Santa Maria, Santa Maria, RS 97110-970 Brazil.
authors.forename: Renan
authors.initials: R
authors.lastname: Dos Santos Carvalho
authors.affiliation: Research Centre in Evolutionary Anthropology and Palaeoecology, School of Natural Sciences and Psychology, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF UK.
authors.forename: Carlo
authors.initials: C
authors.lastname: Meloro
keywords: Canidae; Carnivora; Climatic adaptations; Geographic clines; Interspecific competition; Macroecology