Garrigan Lab

  Garrigan Lab Research

Human Haplotype Variation in Sub-Saharan Africa

Sub-Saharan African populations hold the key to understanding human origins. Because non-African human populations experienced a strong founder event as they dispersed from Africa, their genomic variation carries little information about ancient human evolutionary history. This project aims to characterize the patterns of nucleotide variation in several agricultural and hunter-gatherer populations from sub-Saharan Africa use the data to test models of human origins, asking whether the lineage leading to modern humans consisted of one or more distinct populations.

Global Human Inversion Polymorphism

Large chromosomal inversions are expected to be highly deleterious due to crossing-over during meiosis, yet we observe that there are many fixed chromosomal rearrangements between species and also that inversions can be highly polymorphic within species. While there are many explanations for why this may be, our laboratory is focused on documenting the distribution and frequency of large chromosomal inversions in the global human population.

X Chromosome versus Autosomal Variation

The haplo-diploid X chromosome is expected to show 3/4 the amount of genetic variation compared to the autosomes. However, the X chromosome of many human populations show levels of genetic variation that are equal to, or greater than, that of the autosomes. Our lab is investigating how high variance in male reproductive success affects the ratio of X to autosomal diversity.

Coalescent-Based Models of Speciation

This project aims to use whole-genome data to distinguish between four different models of speciation in Drosophila simulans and Drosophila mauritiana.

Modeling the Structure of Genomic Variation

The goal of this project is to incorporate the Sequential Markov chain (SMC) method for generating correlated coalescent genealogies into complex models of population structure and examine how gene flow between populations affects the autocorrelation of evolutionary histories throughout the genome.