Environmental correlates of geographical variation in skull and mandible shape of the punaré rat Thrichomys apereoides (Rodentia: Echimyidae)

Authors

  • Leandro R. Monteiro,

    Corresponding author
    1. Laboratório de Ciências Ambientais, CBB, Universidade Estadual do Norte Fluminense, Av. Alberto Lamego 2000, 28013-600 Campos dos Goytacazes, Rio de Janeiro, Brazil
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  • Luiza C. Duarte,

    1. Departamento de Parasitologia, Instituto de Biologia, Universidade Estadual de Campinas, Caixa Postal 6109, 13083-970 Campinas, São Paulo, Brazil
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  • Sérgio F. dos Reis

    1. Departamento de Parasitologia, Instituto de Biologia, Universidade Estadual de Campinas, Caixa Postal 6109, 13083-970 Campinas, São Paulo, Brazil
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*L. R. Monteiro. E-mail: lrmont@uenf.br

Abstract

The pattern of correlations between geographic–environmental variables and geometric shape descriptors for the skull and mandible of Thrichomys apereoides was studied by recently developed combinations of geometry and multivariate statistical techniques. Environmental variables were obtained for each locality: altitude, mean temperature, rainfall, human population density, and vegetation type. The three views of the skull (dorsal, lateral and ventral) and the mandible were significantly associated with a latitudinal environmental gradient along the diagonal of open areas (caatinga and cerrado) throughout the range sampled. The populations from xeric environments presented relatively larger coronoid processes, larger jugals and wider snouts (related to the activity of jaw closing muscles). A correlation of patterns of shape variation from data sets of different skull views showed that lateral skull shape is the most informative view. Further studies are necessary to separate completely the contribution of genetic and environmental components to skull and mandible shape divergence among populations of T. apereoides.

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