Integration and Modularity of Quantitative Trait Locus Effects on Geometric Shape in the Mouse Mandible

Christian Peter Klingenberg, Larry J. Leamy, James M. Cheverud

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The mouse mandible has long served as a model system for complex morphological structures. Here we use new methodology based on geometric morphometrics to test the hypothesis that the mandible consists of two main modules, the alveolar region and the ascending ramus, and that this modularity is reflected in the effects of quantitative trait loci (QTL). The shape of each mandible was analyzed by the positions of 16 morphological landmarks and these data were analyzed using Procrustes analysis. Interval mapping in the F2 generation from intercrosses of the LG/J and SM/J strains revealed 33 QTL affecting mandible shape. The QTL effects corresponded to a variety of shape changes, but ordination or a parametric bootstrap test of clustering did not reveal any distinct groups of QTL that would affect primarily one module or the other. The correlations of landmark positions between the two modules tended to be lower than the correlations between arbitrary subsets of landmarks, indicating that the modules were relatively independent of each other and confirming the hypothesized location of the boundary between them. While these results are in agreement with the hypothesis of modularity, they also underscore that modularity is a question of the relative degrees to which QTL contribute to different traits, rather than a question of discrete sets of QTL contributing to discrete sets of traits.
    Original languageEnglish
    Pages (from-to)1909-1921
    Number of pages12
    JournalGenetics
    Volume166
    Issue number4
    DOIs
    Publication statusPublished - Apr 2004

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