Research Interests
NUTRIENT ALLOCATION TO REPRODUCTION IN INSECTS
How animals allocate nutritional resources to reproduction is a poorly-understood physiological process with profound evolutionary consequences. Much of my work has investigated how nectar-feeding butterflies and moths meet the nutritional demands of oogenesis, given that their adult diets contain primarily sugar. The relative contribution of larval vs. adult dietary resources to reproduction and survival (somatic maintenence) is strongly tied to insect life histories. I use stable isotope signatures as dietary markers to characterize C and N allocation from the larval and adult diets into egg manufacture. Recently I've been using compound specific C isotope analysis to investigate the dietary sources (larval vs. adult) of the carbon backbones of amino acids used in egg manufacture in a variety of species. Essential amino acids are in limited supply for many phytophagous insects, and how these nutritional demands are met is an area of active interest. My work on butterflies has been conducted in collaboration with Dr. Carol Boggs at Stanford University and Dr. Marilyn Fogel at the Carnegie Institution of Washington
This work has been extended recently to investigating the nutritional basis of the survival-fecundity tradeoff in fruit flies, in collaboration with Dr. Marc Tatar and Dr. Kyung-Jin Min at Brown University. In Drosophila, larval and adult diets are identical but the lifestages may process and absorb nutrients differently. How nutritional resources from the lifestages are allocated between reproduction and somatic maintenance is unknown, although diet restriction in larval adult lifestages has differential impacts on survival and reproduction.
USING STABLE ISOTOPE SIGNATURES AS HUMAN DIETARY BIOMARKERS
This work is quite new, and is being developed in collaboration with the Center for Alaska Native Health Research at UAF [CANHR]. I am interested in whether naturally occuring isotopic variations in subsistence and nonsubsistence foods can be used to characterize important dietary differences between individuals in Alaska Native communities. If so, these signatures could serve as an easy, noninvasive way to accurately characterize aspects of human diets. Accurate dietary biomarkers facilitate comparing diet pattern with phenotypes related to health, specifically risk of obesity and diabetes. I currently have an undergraduate honors student working on this project, and am interested in recruiting a graduate student.
STABLE ISOTOPIC MARKERS OF NUTRITIONAL STATUS
Very generally, I am interested in how dietary and physiological processes (nutrient routing and metabolism) leave isotopic "fingerprints" in animal tissues, and how these signatures might be used to index a wide variety of nutritional phenomena. I welcome graduate students with an interest in pursuing these questions in a variety of different systems.
Teaching
- Fundamentals of Biology I (BIOL 105X)
- Animal Physiology (BIOL
310)
- Animal Stable Isotope Ecology (BIOL 693, Special Topics)
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Education
- PhD 1998 Princeton University, Dept of Ecology and Evolutionary Biology
- BA 1991 Amherst College, Department of Biology
Professional
Experience
- 2004 –
Assistant Professor
Institute of Arctic Biology / Biology and Wildlife.
University of Alaska, Fairbanks
- 2003 – 2004
Assistant Professor
Department of Biological Sciences
Wellesley College
- 2001 – 2002
Visiting Assistant Professor
Department of Biology
Swarthmore
College
- 1998 – 2001, 2002 - 2003
Postdoctoral Researcher
Center for Conservation Biology
Stanford
University
and
Visiting Scientist
Geophysical Laboratory
Carnegie
Institution of Washington
Publications
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O’Brien, D.M., K.J. Min, T. Larsen, and M. Tatar 2008. “Testing how diet restriction extends lifespan in Drosophila with stable isotopes” Current Biology 18(4) R155-R156. [PDF]
- O'Brien, D.M. and Wooller, M.J. 2007 "Tracking human migration using stable oxygen and hydrogen isotope analyses of hair and urine”. Rapid Communications in Mass Spectrometry 21: 2422-2430. [PDF]
Wilkinson, M.J., Yai, Y. and O'Brien, D.M. 2007. "Age-related variation in red blood cell stable isotope ratios (d13C and d15N) from two Yup'ik villages in Southwest Alaska: a pilot study." International Journal of Circumpolar Health 66(1): 31-41 [PDF]
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Scott, J.H., D.M. O'Brien, D. Emerson, H. Sun, G.D. McDonald, A. Salgado, M.L. Fogel. 2006. "An examination of the carbon isotope effects associated with amino acid biosynthesis". Astrobiology 6(6):867-880. [PDF]
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Min, K.J., M. Hogan, M. Tatar, and D.M. O'Brien. 2006. "Resource allocation to reproduction and soma in Drosophila: a stable isotope analysis of carbon from dietary sugar." Journal of Insect Physiology 52(7): 763-770. [PDF]
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Suarez, R.W., C.A. Darveau, K. Welch, Jr., D.M. O'Brien, D.W. Roubik, P.W. Hochachka. 2005. "Energy metabolism in orchid bee flight muscles: Carbohydrate fuels all". Journal of Experimental Biology 208: 3573-3579. [PDF]
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O'Brien, D.M., C.L. Boggs,
and M.L. Fogel 2005. "The amino acids used in reproduction by butterflies:
a comparative study of dietary sources using compound specific
stable isotope analysis." Physiological and Biochemical Zoology 78(5):819-827. [PDF]
- Fisher,
K, D.M. O’Brien, and C.L. Boggs 2004 "Allocation
of larval and adult resources to reproduction in a fruit-feeding
butterfly." Functional Ecology, 18:656-663. [PDF]
- O’Brien,
D.M, C.L. Boggs and M.L. Fogel. 2004 "Making eggs
from nectar: the role of life history and dietary carbon turnover
in butterfly reproductive resource allocation." Oikos 105:
279-291. [PDF]
- O’Brien,
D.M, C.L. Boggs and M.L. Fogel. 2003. "Pollen feeding
in Heliconius charitonius: isotopic evidence for essential
amino acid transfer from pollen to eggs." Proceedings of
the Royal Society of London: B 270 (1533): 2631-2636. [PDF]
-
O’Brien,
D.M., Fogel, M.L., and C.L. Boggs. 2002. "Renewable and non – renewable
resources: amino acid turnover and allocation to reproduction
in Lepidoptera." Proceedings of the National Academy of the Sciences
USA 99(7): 4413-4418. [PDF]
-
O'Brien,
D.M. and R.K. Suarez. 2001. "Fuel use in hawkmoth (Amphion
floridensis) flight muscle: enzyme activities and flux rates." Journal
of Experimental Zoology 290:108-114. [PDF]
-
O'Brien,
D.M., D.P. Schrag, and C. Martínez del Rio. 2000. "Allocation
to reproduction in a hawkmoth: a quantitative analysis using
stable carbon isotopes." Ecology 81:2822-2831. [PDF]
-
O'Brien,
D.M. 1999. "Fuel use in flight and its dependence on nectar
feeding in the hawkmoth Amphion floridensis." Journal of
Experimental Biology 202:441-451. [PDF]
-
Gannes,
L.Z., D.M. O'Brien, C. Martínez del Rio 1997. Stable isotopes
in animal ecology: Assumptions, caveats, and a call for more
laboratory experiments. Ecology 78:1271-1276. [PDF]
A few favorite bugs
 Amphion floridensis  Euphydryas chalcedona
 Speyeria mormonia
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