Biogeographic Analysis Using Geometric Morphometrics: Clines in Skull Size and Shape in aWidespread African Arboreal Monkey

Despite the “renaissance” of biogeography in the last two decades with its centralrole in the study of biodiversity and evolution, and the “revolution” in morphometricsbrought about by methods based on the analysis of Cartesian coordinates ofanatomical landmarks, the use of geometric morphometrics in biogeographic studieshas been rather limited. With this analysis we aim to provide an example ofhow geometric morphometrics can fruitfully be applied to the study of clinal variationin a widespread African monkey group by a simple extension of methodswidely employed by macroecologists and biogeographers to multivariate shape data.Throughout the paper we aim to explain these techniques so that those who are newto them can use and adapt them for their own needs, in some cases providing specificinstructions on how to perform certain operations in standard morphometricsand statistical software. Our hope is that this may stimulate morphometricians andscientists from other disciplines to explore geographic variation in size and shapeusing up-to-date geometric morphometric methods. The application of geometricmorphometrics to ecological, biogeographic and phylogeographic studies has enormouspotential for a thorough understanding of how form changes in space and timeduring evolution and in relation to genetic and environmental factors.