Songbirds harbor an extra chromosome within their germline cells that aren't present in their other cells, New Scientist reports.
It adds that this phenomenon was first noticed in zebra finches in the late 1990s and now researchers from the Institute of Cytology and Genetics in Russia have found this pattern among other songbirds as well. As they report in the Proceedings of the National Academy of Sciences this week, the Russian team used antibodies to the synaptonemal complex of meiotic chromosomes to find that all 14 of the songbirds they investigated had this extra chromosome, while the eight other non-songbirds studied did not. The researchers note that that the size of the added chromosome varied from species to species, and they hypothesize that extra germline chromosome could be the result of a whole chromosome duplication in the ancestral songbird genome that underwent changes in its descendants.
New Scientist adds that this extra chromosome could provide an advantage and account for why songbirds make up about half of the 10,000 or so known bird species.