Dissertation Research: Reconstructing a mitogenome-based intraspecific tree to test for phylogenetic inertia in a morphological study of island dwarfing in Southeast Asian mammals

University Of Chicago, Chicago IL

Investigators

Abstract

This project explores what happens to mammals isolated on islands. According to a generalization known as the ?Island Rule?, there is a trend on islands for large-bodied species to evolve smaller body size (island dwarfing) because food resources are severely limited. However, little work has been done on changes in individual anatomical components, such as brain size and skull shape, that accompany decreases in body size. The overall goal of this research is to explore potential differences in brain size and skull morphology between island and mainland representatives of large-bodied mammals in Southeast Asia: deer, pigs and primates. The research will use DNA sequencing to resolve relationships among island populations and take these relationships into account during statistical analyses. Because this research is based at The Field Museum in Chicago, the researchers are actively involved with a wide range of outreach programs directed toward museum visitors, which allow both adults and students to learn about evolution on islands. Together, the outreach and investigation of mammal diversification on islands will contribute to public understanding of the evolutionary history of life. This project will explore how intraspecific relatedness influences skull morphology and brain size in island mammals. To achieve this, researchers will focus on the long-tailed macaque, Macaca fascicularis, because it is the most widespread primate species in Southeast Asia. They will generate a well-resolved population-level phylogeny for museum specimens based on entire mitochondrial genomes. DNA will first be extracted from dried tissue samples from museum specimens in a sterile, ancient DNA lab at University of Illinois Urbana-Champaign. Then, the scientists will build genetic libraries for each sample and target only the genomes of the mitochondria using specific enrichment techniques. These enriched samples will then be used for high-throughput sequencing. The resulting mitochondrial sequences will be trimmed and assembled, for reconstruction of a robust within-species phylogeny. The inferred tree will be used to control for relatedness in statistical analyses of brain size and skull morphology, and to gain insights into (a) the relative timing of colonization of Southeast Asian islands by M. fascicularis, especially of smaller islands, and (b) overall phylogeographic patterns and rates of diversification.