Friday, February 13, 2015

National Cockroach Project

In 2009, high school students found novel DNA barcode types in American cockroaches (Periplaneta americana) in New York City. These first preliminary results also indicated that cockroaches in certain city neighborhoods of New York share the same genetic makeup but differ from roaches in their neighboring hoods. This led to a new national project for high school students spearheaded by Mark Stoeckle, Rockefeller University, New York. The goal of the project was to learn more about this feared and despised yet ineradicable urban denizen.

The National Cockroach Project was announced in late 2012 called on high school students and other citizen scientists across the US to sample cockroaches and send them in for barcode sequencing. The main questions of the project were:

Do American cockroaches differ genetically between cities?
Do US genetic types match those in other parts of the world?
Are there genetic types that represent undiscovered look-alike species?

Now a little over 2 years later the project came to a close and the results were just published in Scientific Reports:

Our sampling effort generated 284 cockroach specimens, most from New York City, plus 15 additional U.S. states and six other countries, enabling the first large-scale survey of P. americana barcode variation. Periplaneta americana barcode sequences (n = 247, including 24 GenBank records) formed a monophyletic lineage separate from other Periplaneta species. We found three distinct P. americana haplogroups with relatively small differences within (≤0.6%) and larger differences among groups (2.4%–4.7%). This could be interpreted as indicative of multiple cryptic species. However, nuclear DNA sequences (n = 77 specimens) revealed extensive gene flow among mitochondrial haplogroups, confirming a single species.

According to the authors, the most likely explanation for the detected genetic pattern is multiple human-mediated introductions from allopatric source populations followed by global dispersal among commercial centers. In fact, the different haplogroups must have diverged long before human-aided dispersal, even if the highest mutation rate estimates of insect mtDNA are applied.

This project is a great example for a citizen science project that did important research which has been recognized by being published in a peer review journal. Remarkably one of the study authors is a high school student and another one is a college undergrad. 

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