Tuesday, February 26, 2013

Fulbright Fellowship at the University of Wyoming

Since September I have been a Fulbright Fellow at the University of Wyoming. If you're a Canadian interested in doing study or research in the USA, check out the Fulbright Canada webpage (http://www.fulbright.ca/). I've been working in the lab of Dr. Mark Clementz (http://www.uwyo.edu/profiles/faculty-staff/mark-clementz.html), a specialist in the areas of isotope ecology and marine mammal palaeoecology. Dr. Clementz has written some of the seminal papers in marine mammal isotope ecology. I'm also working with Dr. Clementz's recent postdoctoral fellow, Dr. Sora Kim (http://geofaculty.uwyo.edu/skim11/Welcome.html). Dr. Kim is an isotope ecologist and has worked primarily on extant and fossil shark ecology.

My Fulbright project is focused on patterns of oxygen isotopes (from phosphates and carbonates) in the teeth and bone of pronghorns (Antilocapra americana). Pronghorns are "wicked cool" hoofed mammals from the family Antilocapridae. They are not members of the family AntiloCRAPridae, as I once reported in a departmental seminar. They are the only living or extant member of the family but were preceded by a large number of extinct species. I always have to mention the fact that they are the the fastest land mammal in North America (much faster than their current predators). Their speed is usually discussed as a hold over from times when faster predators pursued them.

Besides their coolness, why did I choose to work on pronghorns?

The obvious answer to the question is that UW houses a very large collection of modern and archaeological pronghorn specimens. But I had other motivations. First, pronghorns have an extensive geographic range (northern mexico to southern Alberta). This enables the study of geographic variation in pronghorn isotope values. From this you can create "isoscapes" and compare them to values from rainwater (http://wateriso.eas.purdue.edu/waterisotopes/). Second, because pronghorns are a game animal, they are numerous in collections all over the USA and Canada. These collections span thousands of years, enabling researchers to study temporal changes in pronghorn isotope values, which is relevant to changes in migration and climate change (among other things).

What isotopes am I using and why?

Stable oxygen isotope ratios covary with temperature and rainfall, thus varying with distance from the coast, latitude, and altitude (check out an isoscape of oxygen here http://iamtheweather.com/vveather/wp-content/uploads/2010/07/beverages.jpg). I am now about to describe geographic variation in oxygen isotopes as briefly as possible (so don't expect to become an expert!). Oxygen isotopes change with distance from the coast and with altitude due to the preferential rain out of heavy (18O rather than 16O) isotopes closer to the coast and at lower altitudes. So rainwater isotopes become progressively lighter inland and at higher altitudes. This explains some of the latitudinal variation in oxygen isotopes. Ambient temperature also affects oxygen isotopes in water on the ground. At high temperatures (low latitudes), the light isotope is evaporated from the ground, leaving more of the heavy isotope. At cooler temperatures (high latitudes), less of the light isotope is evaporated. This is an oversimplified explanation of oxygen isotopes but should give you a basic understanding of why oxygen isotopes vary across North America as in the linked map. I'm sure my temporary lab mates are ganging up for attack!

What is the purpose of my research?

My mains goals involve characterizing changes in oxygen isoscapes from mammals under conditions of climate change because these changes can provide indirect evidence for changes in terrestrial rainfall and temperatures on long timescales (thousands to millions of years).

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