DISSERTATION RESEARCH: Reassessing the role of the Great American Biotic Interchange in the evolution of the raccoon family

George Mason University, Fairfax VA

Investigators

Abstract

The Great American Biotic Interchange (GABI) was a major biogeographic event that connected the terrestrial animal communities of North and South America via the closure of the Panamanian Isthmus. Geological evidence and the fossil record have suggested that the closure of the isthmus occurred 3 million years ago (mya), but more recent studies suggest a much older age for the formation of a landbridge between North and South America, around 15 mya. Among mammals of North American origin, the raccoon family (Procyonidae), which also includes coatis, kinkajous, olingos, and ringtails, has one of the longest histories in South America. The fossil record shows that an extinct member of this group was the first North American mammal to immigrate to South America, approximately 7-9 mya. While the prevailing hypothesis states that immigration of modern members of this group took place 3 mya, recent estimates based on DNA sequence data revealed that this family has had a much longer tenure in South America. This study will more thoroughly test competing hypotheses regarding the process and timing of evolution of this group, with the potential to revise our understanding of mammal evolution in the Neotropics, while contributing to advancement in the fields of genomics, systematics, taxonomy, and biogeography, as well as promoting the professional development of an early-career female STEM researcher. This project will use an integrative approach to test competing hypotheses based on genomic analyses of museum specimens, morphometrics, and biogeographic modeling. Ancient DNA techniques in combination with high-throughput sequencing methods will be used to sequence mitochondrial genomes as well as to sample the nuclear genome using a novel intron-capture microarray. Morphometric data will be analyzed separately and in conjunction with comparative genomic data to test hypotheses regarding procyonid evolution and revise the taxonomy of this group. A new biogeographic model for the evolution of the raccoon family that accommodates the most recent DNA and geological evidence will be tested against the traditional fossil-based hypothesis, and will integrate phylogenetic data to reassess the tempo and geographic pattern of diversification associated with the GABI. Results will be shared through scientific publications co-authored by the PI, Co-PI, and collaborators. Genomic and morphological data, protocols, scripts and parameters used in the analyses will be made publicly available through the electronic repositories of NCBI?s Genbank and Dryad.