The project brought in more than 120 roaches, and associated genetic sequences, from around the world, including from Australia and Spain, although most hailed from New York. (Before this project, there were only two dozen published sequences of roach DNA, Stoeckle said). Xia's analysis showed that the Big Apple hosts more roach diversity than any known spot - all four recorded haplotypes of American cockroaches are found here, Stoeckle said.
Furthermore, roaches tended to cluster into different neighborhoods. Almost all of the roaches found on the Rockefeller University campus, for example, belonged to one group, which differed from almost all roaches found on the Upper West Side.
" that way, they are a lot like people - a lot like New Yorkers," Stoeckle said.
The study raised more questions than answers, however. For example, why did American cockroaches (Periplaneta americana) diverge into different subgroups millions of years ago, without branching out into different species? (Different species, according to the biological species concept, are reproductively isolated from one another, and don't interbreed.) And where, exactly, did the cockroaches originate?