Doctoral Dissertation Research: An analysis of the evolution of shape change trajectories using 3D geometric morphometrics

University Of Oregon Eugene, Eugene OR

Investigators

Abstract

In closely related animal species, differences in patterns of growth and development are often responsible for differences in adult anatomy. This doctoral dissertation project will study cranial anatomy in a number of primate species, taking into account trajectories of growth and development, and use those data to reconstruct the growth and development trajectories of ancestral species. The project will advance knowledge about primate adaptation and life history, and will also generate novel shape measurement tools for studying growth, development and anatomy that will be useful across a number of biological disciplines. Undergraduate students will participate in the processing and analysis of shape measurements, thereby teaching them technical skills in geometric morphometrics, mathematics, and statistical analysis. The project will also support public science outreach activities to share these biological concepts and methodological advances with a broader audience. The objective of this investigation is to examine how evolution has shaped craniofacial growth and development to produce the morphological diversity observed in catarrhines. Geometric morphometric methods will be used to measure an ontogenetic cranial series of 26 extant catarrhine species, from which trajectories of ontogenetic shape change will be calculated. To address ancestral morphologies, this project will reconstruct the cranial ontogenetic trajectory of the last common ancestor (LCA) of all extant catarrhines, as well as those of the LCA of cercopithecoids, hominoids, and hominins, allowing for a comparison of ancestral trajectories with those of extant taxa. As adult morphologies are largely the product of patterns of growth and development, these ancestral ontogenetic trajectories will be used to make determinations about the cranial shapes of adult catarrhine ancestors. This project will also address the role of cranial size in the production of adult morphologies through an evaluation of the hypothesis of size as a 'line of least evolutionary resistance,' whereby size changes may be a first step in adaptation and diversification, with size responding more quickly than shape to environmental change. Using the latest advances in phylogenetic comparative methods, this hypothesis will be tested through direct comparisons of vectors of ontogenetic shape change in the catarrhine skull, and by examining the catarrhine phylogeny for rate shifts in the evolution of cranial size and in cranial size-shape relationships. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.