Evrim Fer, Testing Natural Selection on Polygenic Trait-Associated Alleles in Anatolia Using Neolithic and Present-Day Human Genomes

M.S. Candidate: Evrim Fer

Program: Bioinformatics

Date: 29.07.2019

Place: A-212

Abstract: Human populations have colonized diverse environments and adaptations to different physical, cultural and dietary transitions have shaped their genome. Similarly, the Neolithic transition which has started approximately 10,000 year ago in west Eurasia and introduced sedentary life style and food production, created a major shifts in human diet (Adler et al., 2013). In many studies, strong selection signals on the genes related to more plant-based diets (Buckley et al., 2017; Harris et al., 2019), consumption of dairy products that evidence of animal domestication (Bersaglieri et al., 2004; Schlebusch et al., 2013)  have been detected in modern populations. With the advent of archeogenomics studies, those adaptations have also been supported using ancient DNA sequences (Allentoft et al., 2015; Mathieson et al., 2015). In this study, polygenic adaptations in Anatolia after the Neolithic transition were investigated by comparing Neolithic and modern-day genome sequence data. First, we chose 40 mainly polygenic traits potentially associated with diet, immunity and other related complex traits, and previously subject to genome-wide association. For 6651 single nucleotide polymorphisms (SNPs), we compared the genetic distance between Neolithic Anatolian (n=36) and present-day Anatolian (n=16) individuals, measured using the FST statistic, with 1,192,246 SNPs in evolutionary neutral regions. Then, the frequencies of risk-alleles having increase effect on phenotype were compared to test for a common direction of allele-frequency change affecting these traits. Finally, a genome-wide selection analysis was performed using the population branch statistic approach to detect adaptation signals specific to the modern-day Anatolia in comparison to Neolithic Anatolia and an outgroup population. We found, the frequency of alleles related to lipid metabolism to be to be more differentiated between Neolithic and present-day Anatolia, than neutrally expected.