Genetic and Morphological Evidence for Local Climate Adaptation in the Americas

• Main Author: Battista, Vincent
• Other Authors: Bigham, Abigail Winslow, Wolpoff, Milford H, Byrd MD MS, J Brian, Devlin, Maureen J, Ocobock, Cara
• Format: Thesis
• Language: English
• Published: 2022
• Subjects: local adaptation; population genetics; Communications; Social Sciences; Tundra; Siberia
• Online Access: https://hdl.handle.net/2027.42/172542; https://doi.org/10.7302/4571

This dissertation investigates environmental drivers of genetic and morphological variation in the American tropics. Using SNP data and spatially-dense 3D craniofacial landmarks, this project will test the hypotheses that: (1) Mesoamerican populations will show evidence of selection on genes that protect against heat stroke; (2) highland Andeans will show signals of selection on genes that protect against hypothermia, and (3) highland Andeans will exhibit craniofacial changes associated with enhanced conditioning of cold, dry air. Over the past two million years, humans dispersed across the planet and managed to thrive in a variety of distinct ecological niches -- a process often facilitated by local adaptive evolution. Classic examples of this include high altitude (e.g., Andes) and circumpolar zones (e.g., Siberia), where humans have adapted to low oxygen availability and low ambient temperatures. Despite the extreme temperatures of high altitude (cold/arid) and lowland rainforest (hot/humid), there have been very few studies (if any at all) to examine the genetic substrate of local adaptation to these specific ecological niches. To fill this void, this dissertation applies a population genetics framework to identify targets of selection in two Indigenous communities from Central and South America. To investigate putative adaptations to high heat and humidity, Chapter 1 interrogates SNP data from 65 Mexican Mayans from the Yucatán Peninsula. To identify putative adaptations to the tundra- like environment of high altitude, Chapter 2 reports selection scans on SNP data derived from 514 Peruvian Quechua. Chapter 3 reports a geometric morphometrics analysis on facial reconstructions from these two populations: using spatially-dense 3D point clouds, this project xv investigates whether the Andean sample follows craniofacial patterns associated with cold climate that are exhibited in populations from high-latitude or circumpolar environments. The results indicate that both populations underwent strong selective ...