Let the Bird-Bugs Bite - Exel: Drexel University's Research Magazine
 
 

_FEATURE

Let the Bird-Bugs Bite
Hiding in the feathers of the birds of the Earth, there is a whole other world just waiting to be unruffled.

_Jason Weckstein

Weckstein is an avian evolutionary biologist who serves as associate curator of the Ornithology Department at the Academy of Natural Sciences of Drexel University and as an associate professor in Drexel’s Biodiversity, Earth and Environmental Science Department.

Perhaps only Jason Weckstein, an expert in bird lice, would refer to the raining down of parasites from a fumigated bird specimen as “a mine full of riches.”

The sight of their tiny corpses trickling from hiding places amongst the barbs of the bird’s feathers can set Weckstein’s mind reeling. He knows they have a story to tell and he is one of a small minority of scientists tuned to listen.

Weckstein is a self-described “dual personality,” a kind of hybrid scientist who studies both birds and the parasites that love them, with a particular focus on avian chewing lice. As an evolutionary biologist, Weckstein considers it his duty to fill in gaps in the tree of life, and parasites can reveal much about their hosts, he says.

“Birds are whole little worlds in themselves and filled with different creatures living on them and in them,” Weckstein enthuses. “It’s a great system for asking a lot of questions.”

Thirty to 70 percent of life on Earth is parasitic, Weckstein explains, and there is good reason the range is so broadly estimated.

This close-up of a louse species (Austrophilopterus cancellosus) feasting on the feather of a toucan (Ramphastos tucanus cuvier) was taken from samples collected during a 2007 expedition to Brazil. This louse species is part of group known for piggybacking on hippoboscid flies to reach new hosts.

“There is so much unknown life on our planet — there are unknown birds on our planet, and there is certainly unknown diversity within species of birds on our planet that we don’t understand,” he says. “If we want to conserve it, if we want to know anything about it, we’ve got to study it.”

Currently, Weckstein is the lead principal investigator on a project funded by the National Science Foundation to conduct collaborative biodiversity surveys to collect, preserve and study avian parasites. The main focus of the project is parasites that are associated with birds that inhabit several geographically isolated areas of southern Amazonian Brazil.

Weckstein works closely with colleague Alexandre Aleixo, curator of birds at the Museu Paraense Emílio Goeldi in Belém, Brazil, to collect bird specimens that will be added to the collections of both the Academy and the Museu Goeldi.

The project team, which also includes colleagues at the University of North Dakota and The Field Museum in Chicago, will analyze genetic data for these birds and their parasites to reconstruct their evolutionary histories.

Into_The_Amazon

This year, Weckstein mapped out two expeditions to Amazonian Brazil. One was planned for this summer to the Caxiuanã National Forest to conduct a faunistic survey of birds and their associated parasites, part of an NSF-funded project with colleagues at the Museu Goeldi in Belém, Brazil; University of North Dakota; and the Field Museum. A second expedition is planned for the fall and will go up the Rio Purus, a south bank tributary of the Rio Amazonas and a relatively unexplored part of western Brazilian Amazonia.

Weckstein is interested in more than just filling in the tree of life. He’s also curious about parasites’ dispersal behavior. Many types of parasites are host-specific and remain on one bird species for an entire life cycle (usually about a month). But Weckstein’s fieldwork and laboratory work, in collaboration with colleague Michel Valim at the Museu de Zoologia da Universidade de São Paulo, has turned up interesting instances of dispersal of parasites from one host group to another, a key precursor to host-switching — a louse species that is typically found on trogons (gaudy perching birds endemic to the tropics) was discovered on a toucan, for example.

How did that happen? One method lice use to disperse between hosts, Weckstein says, is by phoresis, which is kind of like hitchiking or piggybacking. This is done with the help of a hippoboscid fly, another insect that parasitizes birds. Basically, Weckstein explains, “lice attach to the body of the fly and ride the fly like a bus to a new host.”

“We found a fly with a trogon louse attached to it and this fly was on a toucan,” he says. “It’s a great example of one of the ways in which parasites can make their way onto new hosts, what we call ‘straggling.’ Over long periods of evolutionary time, these ‘accidental’ straggling events can lead to host switching, which is an important way that parasites and pathogens move between host groups.”

And there’s a bigger application here — studying patterns of parasite transmission and evolution can help scientists trace similar patterns in the evolution of pathogens such as malaria and Ebola, Weckstein points out.

“The more we know about parasites and their relationships with their hosts,” he says, “the better prepared we are to understand how parasite diversity is generated and maintained and how diseases travel between birds, parasites and humans.”

The combination of 19th-century collecting and fieldwork and modern-day technology is another reason why Weckstein’s work is so unique.

A_Rare_Bird

Another project of Weckstein’s in progress involves sequencing some small fragments of DNA from the toepads of the type specimen of a bird called the Rio de Janeiro antwren (Myrmotherula fluminensis). This bird is only known from a single specimen, which is housed at the Museu Goeldi in Belém, Brazil. Researchers have long speculated that this specimen was just an aberrant individual of an already described species, or perhaps a hybrid, but Weckstein and his collaborators have collected data that confirm that it is in fact a unique species. Given that it has only been seen this one time, and that it was collected in what is now a very endangered habitat, their work can help bring to light the importance of searching for this bird with the hope of conserving whatever populations may remain.

“One of the things that I love about my job is that I get to have my foot in two places,” Weckstein says. “One is this sort of old-fashioned 19th-century exploratory work in places where we don’t even know what lives there. Then we can come back to the lab and use modern techniques like DNA sequencing, which can inform us about biodiversity and evolution in ways that 19th-century scientists couldn’t even imagine.”

Weckstein says sequencing DNA is another way to add crucial information to the tree of life, and a new generation of DNA-sequencing technology has made it easier and less expensive.

“It used to be that we were sequencing maybe 300 to 1,000 letters of the [DNA] code,” he says. “Now we can sequence millions of letters of the code and it tells a lot more — and we can do it for much cheaper.”

Sequencing the DNA of a louse species, for example, costs about $1,000, Weckstein says. He submitted a preliminary proposal to the NSF earlier this year to continue this work.

“We’re trying to get a good, solid sense of what the evolutionary history is of a particular group, so we’re building the tree of life,” he explains. “In order to know statistically that we have the right tree of life, we need a lot of data. And getting this huge amount of data for a lower price is allowing us to have a much better, more well-supported evolutionary tree.”

“The more we know about parasites and their relationships with their hosts, the better prepared we are to understand how parasite diversity is generated and maintained and how diseases travel between birds, parasites and humans.”

—Jason Weckstein,
Academy of Natural Sciences of
Drexel University

Specimens collected from the field and added to the collections have much more than DNA to offer — there are endless possibilities for study.

“With bird specimens, you can take tissue samples or blood samples for malarial or Lyme disease work, you can use parasites to look at disease ecology or parasite ecology. And that’s not even scratching the surface,” he says. “Ten years from now, someone might want to come in to look at plumage coloration patterns or molt or phylogenetics or any number of things and can use the same specimen.”

Weckstein brings his unusual research focus, experiences from his fieldwork and access to the Academy’s Ornithology Collection — which is the second-largest university-based collection in the world — to a new course for Drexel students that started this year.

“The combo of things that he does gives his research that extra level of interest,” says Ted Daeschler, an associate professor in the Biodiversity, Earth and Environmental Science Department and vice president for collections at the Academy. “He’s innovative, and his research program shows students the power of being open to new methods. It shows students that research is a creative process and they can think a little bit outside the box.”

AIR_MAIL

A pilot project currently underway is looking at Lyme disease in birds. The project involved field work in Pennsylvania including collaborating with the bird banding station at Rushton Woods Preserve in Malvern, Pennsylvania. The work being done may help demonstrate the potential that migrant birds have as vectors for the bacterium that causes Lyme disease. This may help improve understanding of how and why the geographic distribution of Lyme disease seems to be expanding.