You might recall how much I dislike DNA barcoding.
So you can imagine my frustration when, in spite of my best efforts to mount an empirical demonstration of what a waste of time it is, the technique turns out to be extraordinarily useful. I’ve been processing sequence data all day from the barcoding gene (COI) for a set of 7 Pheidole species distributed from Costa Rica to Argentina. The results are in hand, and here are the pairwise genetic distances:
See that blank spot in the middle? That shouldn’t be there. If barcoding didn’t work, that is.
For this sample of ants, then, any two individuals will either be genetically similar (the bars at left), or different (at right), without ambiguous intermediates. So it is relatively easy to predict from the COI sequence whether any two ants belong to the same species. The gap also demarcates the same divisions I’ve found using traditional morphological characters. It’s remarkably clean.