Well it’s that time of year again- field seasons are starting up! It feels like I just got back from Mongolia, but it’s been eight months since we emerged from the Gobi Desert and headed back to Colorado. While we’ve been busy analyzing data in the lab, the barn swallows have been hanging out in the southern hemisphere, gorging on insects and soaking up the warm weather. They’re now flying north for another breeding season- and we’ll be following along to catch them. |
This year the fieldwork plan is short, relatively speaking: 2-3 weeks in Egypt and 4 weeks in China. We have been trying to get to Egypt for the last several years, but political instability has kept us away. It’s finally safe enough for us to visit- protests have subsided, and we have a great local collaborator: Dr. Basma Sheta, a professor at Damietta University. She has arranged for us to capture swallows in Damietta, a city on the Mediterranean coast, near the mouth of the Nile.
The barn swallow subspecies in Egypt, Hirundo rustica savignii, is particularly interesting and important for us to sample. Barn swallows originally evolved in Africa, and spread throughout the northern hemisphere only in the last 100,000 years or so (check out the arrows on the map I've included- they show the colonization history of the species complex). This means that the Egyptian swallows are likely representative of the “ancestral” form- that is, what barn swallows were like when they first diverged from their closest ancestor. The Egyptian swallows have of course changed in the intervening millennia, but comparing them to the birds we study in the northern hemisphere will still be very interesting. For example, Egyptian barn swallows do not migrate- they live year-round in the warm Nile valley. At some point, the other barn swallow subspecies evolved the ability to migrate, and comparing genomes of Egyptian barn swallows to the genomes of migratory subspecies may give some clues about how migratory ability evolved.
The Egyptian swallows are also the only subspecies from which we don’t yet have samples; once we complete our work in Damietta, we will have phenotypic and genomic samples from all 6 subspecies (check out the map again). This complete sampling of the species complex will allow us to reconstruct relationships among subspecies using huge amounts of genomic data. Thus far we’ve been able to study how the different subspecies are related to each other using only mitochondrial DNA and one nuclear gene. Using new genomic methods, we’ll be able to compare subspecies at hundreds of thousands of different points throughout the genome. This should provide a huge improvement in resolution and help us understand how the different populations diverged from each other.
As always, I’ll be posting photos and updates from the field when possible. I’m joined in Egypt by Amanda Hund, a Ph.D. student at CU who studies barn swallow parasites. She writes about her work here- be sure to check out her site for stories about tracking down barn swallows (and their parasites) in the Czech Republic and Israel.
-Liz
As always, I’ll be posting photos and updates from the field when possible. I’m joined in Egypt by Amanda Hund, a Ph.D. student at CU who studies barn swallow parasites. She writes about her work here- be sure to check out her site for stories about tracking down barn swallows (and their parasites) in the Czech Republic and Israel.
-Liz