Studying population genetics and evolutionary theory, applied to human genetic variation

Locations of HGDP Eurasian populations and Native American populations from Wang et al. (2007, PLoS Genetics) that were analyzed by Ramachandran and Rosenberg (2011, AJPA). This comparative study of genetic differentiation on two continents showed that populations are more differentiated along the major axis of the Americas than along the major axis of Eurasia, perhaps due to the relative ease of migration east-west compared to migration north-south.

Figure 7 from Novembre and Ramachandran (2011, Ann Rev Genomics Hum Genet). A schematic of human demographic history, highlighting hypotheses investigated by recent single-nucleotide polymorphism studies discussed in the review. Designed by JN with input from SR.

Conference photo from Human evolution in the genomic era: Origins, populations and phenotypes (1-4 April 2014, Leicester UK). SR was a plenary speaker.

The Ramachandran Lab during Summer 2013.

Schematic figure illustrating population size trajectory estimationg for four sequences, with credible interval. Our approach, led by postdoc Dr. Julia Palacios, is based on the sequentially Markov coalescent with invisible recombination events. Inspiration for the figure was drawn from Rasmussen et al. (2014, PLoS Genetics).

Research in the Ramachandran lab addresses problems in population genetics and evolutionary theory, generally using humans as a study system. Our work uses mathematical modeling, applied statistical methods, and computer simulations to make inferences from genetic data. We answer questions like: what demographic processes characterize the human diaspora out of Africa? did people migrate more rapidly across Eurasia or the Americas? does genetic variation account for some ethnic disparities in disease incidence and outcome? what features of human demographic history can we infer from cultural traits alone?