Thursday, January 14, 2010

Updates on the Escudo Hummingbird Question

The new year starts with an intern, Andrea Baquero, who hails from Colombia working in the lab with me. This week we began to collect nuclear DNA fragments from Amazilia hummingbirds (tzacatl on the mainland and Isla Colon) and handleyi (Isla Escudo) to get a more robust estimate of divergence time and gene flow between Escudo and the mainland. We haven't analyzed the preliminary data yet, but the few sequences that I've seen give me the general impression that gene flow was ceased between Escudo and the mainland for some time now.

I have to say that I'm pretty surprised at the level of DNA polymorphism in the Escudo population. Polymorphism is another word for genetic diversity, and as everyone remembers from high school biology, small inbred populations lose genetic diversity overtime due to genetic drift. However, we only have two small nuclear DNA fragments (as opposed to the mitochondrial DNA fragments I discussed earlier) and so this may be a consequence of chance. We will be collecting more data in the coming weeks, and I'll post an update.

I believe that this would make the Escudo Hummingbird, among all the world's hummingbirds, the species with the smallest range.