No relationship between canalization and developmental stability of the skull in a natural population of Mastomys natalensis (Rodentia: Muridae)

The aim of the present work was to investigate the relationship between canalization and developmental stability under varying environmental conditions. Three different cohorts of Mastomys natalensis (Rodentia, Muridae), displaying different growth trajectories, were analysed by means of geometric morphometrics. A set of 23 landmarks was digitalized on the dorsal skull of 292 specimens from Morogoro (Tanzania). Patterns of among-and within-individual (measured as fluctuating asymmetry, FA) variation were assessed and compared among and within the three groups to test for the presence of a common mechanism between canalization and developmental stability. Results showed that there was no congruence between canalization and developmental stability: (1) levels of FA and among-individual variation varied in a discordant fashion, (2) no correspondence between the variance-covariance matrix of among- and within individual variation was found, and (3) environmental effects were able to alter the covariance structure of among-individual variation leaving patterns associated with fluctuating asymmetry unaffected. These findings support the view of multiple mechanisms underlying developmental buffering of shape variation. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 207-216.