Abstract
Brown rats (Rattus norvegicus) thrive in urban environments by navigating the anthropocentric environment and taking advantage of human resources and by-products. From the human perspective, rats are a chronic problem that causes billions of dollars in damage to agriculture, health and infrastructure. Did genetic adaptation play a role in the spread of rats in cities? To approach this question, we collected whole-genome samples from 29 brown rats from New York City (NYC) and scanned for genetic signatures of adaptation. We applied multiple methods, testing for (i) high-frequency, extended haplotypes that could indicate selective sweeps and (ii) loci of extreme genetic divergence between the NYC sample and a sample from the presumed ancestral range of brown rats in rural north east China. We found candidate selective sweeps near or inside genes associated with metabolism, diet, organ morphogenesis and locomotory behavior. The divergence between NYC and rural Chinese rats at putative sweep loci suggests that many sweeps began after the split from the ancestral population. Together, our results suggest several hypotheses for a genetic component behind the adaptation of rats in response to human activity.
Footnotes
↵* P.S.P. and J.M.-S. jointly supervised this work
