Research Roundup

While I've been in DC, I've been lucky enough to go to three talks by visiting scientist at the National Park Zoo. It's been awhile so I don't remember all the details, but I will try to summarize what I learned as best I can. (Please don't hold me to complete accuracy, but this should give you an idea of their research).

1. Jan Komdeur on Seychelles warblers. Komdeur has been studying the warblers on this tiny island (I think it is about one mile square) for over a decade. He has established that there are times when the female in a pair loses her place to a new female and yet remains on the territory as a helper grandparent of sorts (for more details see this article in the Proceedings of Biological Science). He has been able to determine these kinds of relationships because almost all the birds are banded and their individual lineage is known through observation and genetic testing. He also presented some data on the percentage of male and female offspring who leave their territories. Males tend to disperse farther since they are trying to avoid mating with their mother. Females do not go as far, in part, Komdeur believes, because many (almost half, in fact) females' territories are cuckolded (meaning a male other than the one the female is paired to is the biological father of the young), and so the odds of mating with her father is smaller.

The most interesting part of his research to me was evidence that there is selection for one sex in certain circumstances. I asked Komdeur if he had any thoughts on the mechanism for this selection, and if I remember correctly he thought it was environmentally determined and not influenced so much by the females' body. (There's an article on the topic here).

While all this was interesting, what I enjoyed most was hearing the story of how Komdeur got started. Before he got his PhD or was known as a researcher, he got a year long grant to go to the Seychelles. He related how at the time he didn't know where the Seychelles were and so after he accepted, he and his girlfriend went to the local bookstore and looked up where the Seychelles were because they didn't know and their friends that they asked had no idea either. (The Seychelles are in the Indian ocean, northeast of Madagascar). Komdeur wanted to know why the grant was for such a short period, and it turns out the study program had a high rate of attrition because so many couples split up during their stay on the tiny island. He says he wasn't too worried because he and his girlfriend grew up in the same neighborhood playing together and so they knew how to handle each other in close quarters. And they ended up getting married before he left for the Seychelles so that she could travel there with him, and are still married today.

2. Patricia Parker on diseases on the Galapagos islands. This was my favorite of the talks, being on disease ecology. I learned that the two introduced diseases to the Galapagos islands that are found in wild birds are avian pox and trichomonas. Newcastle disease, Marek's disease and avian mycoplasmosis have also been found in domestic chickens but are not to date a problem for wild birds. Parker talked a bit about the risk from domestic chickens. There are two main sources of chickens, those flown in daily as day old chicks and those that roam free on the island. The reason that the day old chicks are flown in is that it is cheaper for farmers to raise broiler chickens from chicks than eggs, and there is a large demand for chicken from the tourists dining on the island. Parker thinks this practice may change after her study. I forget the exact findings, however.

Avian pox is a disease that causes significant morbidity and mortality for several Galapagos species, the worst affected being the Galapagos mockingbird. Parker was able to show that avian pox did not come from domestic chickens on the island today but rather has been on the Galapagos for over a hundred years. She was able to show this in a really cool way-- she went to the California Academy of Sciences and looked at their collection of birds from the Galapagos from an expedition in the early 1900s. (Ironically, the expedition's aim was to collect birds in order to preserve them for posterity because the leaders of the expedition were convinced Galapagos birds would suffer high rates of extinction, yet this did not come to pass, and instead in a sad turn of events, the scientists' act of taking vast quantities of birds decimated several populations, which luckily have recovered since). It turns out these Galapagos birds preserved at the California Academy of Sciences have visible pox lesions on their feet and Parker got permission to take samples of these lesions from birds that were affected on both feet (that way the curators at the Academy reasoned, it was still obvious which specimens were affected since even if one foot was sampled, the other remained as proof of the pox affliction). Now for the really neat part: Parker sent these samples off to a veterinary pathologist who basically reconstituted them by soaking them in formalin, and then did histopathology that identified the lesions definitively as pox. She also did genetic analysis that showed the pox afflicting the Galapagos birds today is canarypox, not the fowlpox that is found in domestic chickens on the island (article in Journal of Wildlife Diseases). Together these findings indicate that the pox had been introduced to the island a long time ago, in the late 1800s or early 1900s.

Parker also talked a lot about genetics. In particular, I remember being intrigued that Swainson's hawks in the wild differ more from each other than they differ from Galapagos hawks as a species. Because there is so little genetic variation among Galapagos hawks, they carry more parasites, and it turns out the lice hold the key to their populations on different islands' evolutionary relationship to each other. Check out this article in Science Daily which explains it better than me.

Parker's research showed that the smaller the population of a species on an island, the less genetic variation, and the more susceptible the population was to disease. As a result, the Galapagos park service implemented more strict travel restrictions to the smaller islands. The Galapagos already has quite stringent precautions to prevent introduced disease-- all airplane holds are treated (I forget with what). They have a lot to preserve-- only a few species have gone extinct, and there are very few introduced, invasive species, so it is one of the best preserved island ecosystems on the planet.

For an extensive summary of her research, read this.

I would have liked to hear Parker talk more about her plan if avian malaria or West Nile virus is detected on the Galapagos. Both of these diseases would be very difficult to control or eradicate once found on the island, but having an effective plan would be getting one step ahead of the game.

3. Keith Hobson gave a talk on stable isotopes. He covered a lot of ground, and much of the terminology was beyond my knowledge. What I got out of this talk is that it is possible to use stable isotopes to get an idea of where an animal has been, such as a migratory bird, or even a person. However, there are many constraints that one must carefully consider in order to get meaningful data. I forget all the limitations, but there are at least half a dozen. It seems stable isotopes do not work particularly well for raptors, perhaps because they travel over a larger terrain or eat a wide variety of prey. No one really knows. For more reading on his research see this article and this one.