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27.04.2021

Exploring morphological variability with the R packages vcvComp and prWarp, with applications to the primate skull

Colloquium by Dr. Anne Le Maître

Time: Tuesday, 27th April 2021, 11 am sharp

Speaker: Dr. Anne Le Maître

Title: Exploring morphological variability with the R packages vcvComp and prWarp, with applications to the primate skull

Abstract: 
Recent developments in morphometrics enabled quantification of complex morphological traits, with multiple applications in evolutionary biology and ecology. Whereas average shape and the magnitude of morphological variation have extensively been explored, few methods exist to describe and compare covariation patterns in a biologically relevant way. Here I will present two novel methods to address this issue, with associated R packages and applications.

The package vcvComp enables the comparison of covariance patterns using relative eigenanalysis (= relative PCA), an exploratory method in which variance ratios between two groups of individuals are maximised. With an application to the craniofacial shape of anatomically modern human populations, I will show how this method can be (1) to explore the homogeneity of the variance-covariance structure across populations, (2) to perform pairwise comparisons of covariation patterns between populations, and (3) to determine which features are under stabilising vs. divergent selection.

The package prWarp enables the study of shape variation at different spatial scales in a geometric morphometric context, either by a mathematical separation into large-scale and small-scale shape components (partial warps), or by a decomposition of the overall shape into outline and residual shape components. With the example of the midsagittal skull morphology, I will show how this approach can be applied (1) to detect coordinated vs. compensatory growth in the human skull, and (2) to disentangle phylogenetic and adaptive signals in the papionin skull.

These two approaches have numerous applications in evolution, ecology, and even medicine, either for the exploration of covariation patterns across groups for multivariate traits, or for testing hypotheses regarding development, phylogeny, and function, based on geometric morphometric data. 

 

We welcome you all to join us via Zoom and we will send around the specific link on the day before the talk.

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