Novel chromatic and structural biomarkers of diet in carotenoid-bearing plumage by Dr R Bleiweiss
Many captive birds change colour in response to dietary intake of carotenoid pigments, which produce vivid yellows, oranges, and reds. However, evidence for the phenomenon in the wild remains controversial. A study of carotenoid-bearing plumages among more than 50 wild tanager species found that carotenoid intake measured as an amount of dietary fruit (a rich source of carotenoids) was associated with reduced plumage reflectance in the ultraviolet, a band of wavelengths visible to birds but not humans. The effect probably arises from increased pigment concentrations and modifications to the structure of feathers. Thus, birds follow a dress code invisible to humans.
Contact: Dr. Robert Bleiweiss, Department of Zoology & Zoological Museum, University of Wisconsin, Madison, WI 53706, USA
Fitness and evolutionary stability in game theoretic models of finite populations by Dr G Wild and Professor PD Taylor
The mathematical theory of games has proven useful to our understanding of the evolution of social behaviour. These so-called "evolutionary games" seek to identify certain "stable strategies," considered to be the end result of evolution. For mathematical convenience, evolutionary games are often played among members of an ideal infinite population. However, populations in nature are never infinite. Unlike much previous work, this study considers a simple two-player game, played among members of a finite population. We establish that different notions of Darwinian fitness and different formal definitions of stability lead to identical conclusions about the outcome of evolution.
Contact: Dr Geoff Wild, Department of Mathematics and Statistics, Queen's University, KINGSTON, ON K7L 3N6, Canada
Contact: Tim Watson