Skull shapes in the integrated morphospace carry strong phylogenetic signal: the human New World settlement case study

DE AZEVEDO, SOLEDAD; IGNACIO M SOTO; MARTÍNEZ ABADÍAS, NEUS; GONZÁLEZ-JOSÉ, ROLANDO

Early Humans in South America: Recent advances in the discussion on the settlement of the New World

Cambridge University Press

Año: 2014;

The origin and worldwide dispersal of anatomically modern humans is a matter of constant debate, in which skeletal evidences are frequently invoked to reconstruct processes of among-population diversification. However, phylogenetic signals are often blurred, since the vertebrate skull is a complex phenotype where morphological integration and modularity coexist and simultaneously act as covariance generator and structuring processes. The Factor Model proposed by Mitteroecker and Bookstein (2007) allows for the decomposition of the full shape space, in which both integration and modularity contribute to patterns of covariation, into an integrated shape space, where covariation sources are summarized by a few common integrator factors between modules, and a set of modular shape spaces, where local factors influence specific modules. Here we apply the Factor Model and 3D Geometric Morphometric techniques to analyze the integrated and modular shape spaces on skull samples of Native American populations. Our results clearly support the idea that the phylogenetic history of the Native American groups is better recovered in the integrated morphospace. Based on the present results, we suggest that the use of the Factor Model can be of utility to enrich the use and interpretation of morphological diversification on the skull and other complex phenotypes in the context of further evolutionary studies.