Matthew Combs, a Fordham University Louis Calder Center Biological Field Station grad student worked with colleagues from Fordham and the Providence College Department of Biology to sequence the genomes of brown rats in Manhattan, and made a surprising discovery: the geography of rats has a genetic correlation, so a geneticist can tell where a rat was born and raised by analyzing its DNA.
When Combs looked closer, distinct rat subpopulations emerged. Manhattan has two genetically distinguishable groups of rats: the uptown rats and the downtown rats, separated by the geographic barrier that is midtown. It's not that midtown is rat-free—such a notion is inconceivable—but the commercial district lacks the household trash (aka food) and backyards (aka shelter) that rats like. Since rats tend to move only a few blocks in their lifetimes, the uptown rats and downtown rats don't mix much.
When the researchers drilled down even deeper, they found that different neighborhoods have their own distinct rats. "If you gave us a rat, we could tell whether it came from the West Village or the East Village," says Combs. "They're actually unique little rat neighborhoods." And the boundaries of rat neighborhoods can fit surprisingly well with human ones.
Spatial population genomics of the brown rat (Rattus norvegicus) in New York City. [Matthew Combs, Emily E. Puckett, Jonathan Richardson, Destiny Mims and Jason Munshi-South/Molecular Ecology]
New York City Has Genetically Distinct 'Uptown' and 'Downtown' Rats
[Sarah Zhang/The Atlantic]
(via Clive Thompson)
(Image: The Rats (of New York))