This page summarizes my current research projects within the scope of my PhD thesis and beyond.
nutritional physiology and trophic ecology
I am broadly interested in how nutritional needs and physiology are related to trophic ecology. During my PhD, I have focused on the nutritional ecology of highly unsaturated omega-3 fatty acids (HUFA). For my PhD candidacy exam, I synthesized the existing literature on HUFA, which resulted in a review paper. In my review, I discussed the importance of HUFA for animals, the dichotomy between HUFA availability at the base of aquatic and terrestrial food webs, and the ecological implications of mismatches between HUFA supply and demand.
I am also interested in understanding how phylogeny and local food quality as well as trophic ecology influence animals' ability to convert the HUFA precursor ALA into HUFA and in animals' dietary HUFA needs in nature. Riparian insectivorous birds have provided me with an excellent system in which to begin understanding these processes. For example, I've found that Tree Swallows (Tachycineta bicolor) chicks are able to convert ALA to HUFA, but that the efficiency of this process and availability of ALA in their prey is such that HUFA are ecologically essential nutrients for them in natural systems. Compound-specific carbon stable isotope tracers are a key tool that I use in this area of my research.
Twining, C. W., J. T. Brenna, N. G. Hairston, and A. S. Flecker. 2016. Highly unsaturated fatty acids in nature: what we know and what we need to learn. Oikos 125:749-760.
Twining, C. W., P. Lawrence, D. W. Winkler, A. S. Flecker, and J. T. Brenna. 2017. Conversion efficiency of alpha linolenic acid to omega-3 highly unsaturated fatty acids in aerial insectivore chicks. bioRxiv:155499. (In press at Journal of Experimental Biology)
Limnology for the ornithologist
I started out my scientific training in limnology, but have been moving into the terrestrial realm by using my background in aquatic ecology to ask questions in avian ecology. In this research I also borrow tools from nutrition including fatty acid composition analyses, bulk stable isotopes, and compound-specific stable isotopes. In my dissertation, I've also been asking the following questions about riparian aerial insectivores, Eastern Phoebes (Sayornis phoebe), and their prey in natural systems around Ithaca, NY:
- Do emergent aquatic insects contain more HUFA than terrestrial insects and how does their fatty acid composition vary at a landscape level?
- Where do riparian aerial insectivores get their overall diet from and how does this vary at a landscape level? (Bulk stable isotopes)
- Where do riparian aerial insectivores get their HUFA and how does this vary vary at a landscape level? (Compound-specific stable isotopes)
HUFA Effects on developmental performance
I studied how the effects of HUFA on performance for riparian aerial insectivore chicks. I found that increasing HUFA in diet increased growth rates and body condition, in both Tree Swallows and Eastern Phoebes. I also found that decreasing HUFA increased metabolic rates (even after size correction) and that HUFA also increased immunocompetence in Tree Swallows.
Twining, C. W., J. T. Brenna, P. Lawrence, J. R. Shipley, T. N. Tollefson, and D. W. Winkler. 2016. Omega-3 long-chain polyunsaturated fatty acids support aerial insectivore performance more than food quantity. Proceedings of the National Academy of Sciences 113:10920-10925.