Phenotipic evolution of human craniofacial morphology after admixture and gene flow: a geometric morphometrics approach.

MARTÍNEZ ABADÍAS, NEUS; GONZÁLEZ JOSÉ, ROLANDO; GONZÁLEZ MARTÍN, ANTONIO; VAN DER MOLEN, SILVINA; ANTONIO TALAVERA,; PATRICIA HERNÁNDEZ,; MIQUEL HERNÁNDEZ,

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY

Wiley International

Lugar: Hoboken; Año: 2006 vol. 129 p. 387 - 398

0002-9483

An evolutionary, diachronic approach to the phenotypic craniofacial outcome arisen on a human population after high levels of admixture and gene flow was derived by means of geometric morphometrics. Admixture has long been studied by means of molecular data. Nevertheless, few efforts have been made to explain the morphological outcome on human craniofacial samples. The Spanish-Amerindian contact can be considered as a good scenario to test such expectations. Here we present a comparative analysis of craniofacial shape changes observed between two putative ancestral groups, Spanish and pre-contact Aztecs, and two diachronic admixed groups, corresponding to early and late colonial periods from Mexico Central Valley. Quantitative shape comparisons upon Mestizo, Spanish, and Amerindian groups were used to test the expectations which quantitative genetics predicts for a case of admixture. Results show that although the human skull is a complex, integrated structure, the craniofacial morphological outcome observed is, in general terms, predictive of the population structure and history. In fact, results obtained after the craniofacial analysis are in accordance with previous molecular and historical interpretations, which evidence that admixture is a main microevolutionary agent influencing modern Mexican gene pool. However, expectations of the quantitative genetic theory are not straightforward when moderate shape changes are considered. Deviations detected at localized structures, such as the upper and the lower face, highlight the evolution of a craniofacial pattern exclusively inherent of the admixed groups, indicating that quantitative characters might respond to admixture in a complicated, non-directional way.