Abstract: Full sequencing of individual human genomes has greatly expanded our understanding of human genetic variation and population history. Here, we present a systematic analysis of 50 human genomes from 11 diverse global populations sequenced at high coverage. Our sample includes 12 individuals of admixed ancestry that have varying degrees of recent (within the last 500 years) African, Native American, and European ancestry. We find over 21 million single nucleotide variants that contribute to a 1.75-fold range in nucleotide heterozygosity across diverse human genomes with a high of 1 heterozygous site per kilobase in West African genomes to a low of 0.57 heterozygous sites per kilobase in segments inferred to have diploid Native American ancestry from the genomes of Mexican and Puerto Rican individuals. We find evidence for all three continental ancestries in the genomes of Mexican, Puerto Rican, and African American populations, and the genome wide statistics are highly consistent across individuals from a population, once ancestry proportions have been accounted for. Using a generalized linear model, we identify subtle variations across populations in the proportion of neutral vs. deleterious variation, and find that genome-wide statistics vary in admixed populations even once ancestry proportions have been factored in. We further infer that multiple periods of gene flow shaped the diversity of admixed populations in the Americas, with 70% of the European ancestry in today’s African Americans dating back to European gene flow happening only 7–8 generations ago.
Bio: I am a population geneticist whose research focuses on analyzing genome wide patterns of variation within and between species to address fundamental questions in biology, anthropology, and medicine.
During the past nine years as a faculty member at Cornell and Stanford, I have trained 43 post-doctoral fellows and graduate students as primary advisory. My group works on a variety of organisms and model systems ranging from humans and other primates to domesticated plant and animals. Much of our research is at the interface of computational biology, mathematical genetics, and evolutionary genomics. Examples of our research accomplishments include:
• Developing selection maps of the human genome which pinpoint rapidly evolving genes as well as genomic regions subject to strong selective constraint;
• Developing a high-density map of genetic variation in the dog genome and using it to identify genomic regions underlying morphological differences among domestic dog breeds;
• Investigating the fine scale genetic structure of human populations and its implication for genomic medicine.
Our current research focuses on human population genomics and global health including developing statistical, computational, and genomic resources for enabling trans– and multi-ethnic genome-wide association and medical sequencing studies of complex biomedical traits. My lab has both dry and wet lab expertise and students and post-docs from diverse fields including: applied math, biostatistics/statistics, computational biology/bioinformatics, anthropology/evolutionary biology, and genetics/genomics.