The Evolution of Gut Modulation and Diet Specialization as a Consumer-Resource Game
Diet provides an important source of niche partitioning that promotes species coexistence and biodiversity. Often, one species selects for a scarcer but more nutritious food (Thomson gazelle) while another opportunistically consumes low-and high-quality foods indiscriminately (African buffalo). In addition to choosing a diet (selective versus opportunistic), organisms have co-adapted digestion physiologies that vary in size and the throughput rate at which food passes through the gut. We combine these elements into a game of resource competition. We consider a vector-valued strategy with elements of gut size and throughput rate. To the forager, food items now have three properties relating to the value of a particular strategy: profitability (energy gained per unit handling time), richness (energy gained per unit bulk), and ease of digestion (energy gain per unit of passage time). When foraging on foods that differ in profitability, richness, and ease of digestion, adjustment or modulation of gut size and throughput rate leads to digestive-system specialization. Modulation of digestive physiology to a particular food type causes different food types to become antagonistic resources. Adjustment of gut volume and processing thus selects for different degrees of diet specialization or opportunism, and thus may promote niche diversification. This in turn sets the stage for disruptive or divergent selection and may promote sympatric speciation.
KeywordsFood Type Sympatric Speciation Handling Time Evolutionarily Stable Strategy Throughput Rate
Unable to display preview. Download preview PDF.
- R. Cressman (2004), Coevolution, adaptive dynamics, and the replicator equation for a single species with a continuous trait space. Proceedings, International Society of Dynamic Games, Tucson, Arizona, USA.Google Scholar
- J. Garay and L. Eötvös (2004), Adaptive phenotypic change based on ecological stability. Proceedings, International Society of Dynamic Games, Tucson, Arizona, USA.Google Scholar
- C. S. Holling (1965), The functional response of predators to prey density and its role in mimicry and population regulation. Memoirs of the Entomological Society of Canada 45, 1–60.Google Scholar
- W. H. Karasov (1996), Digestive plasticity in avian energetics and feeding ecology. Pages 61–84in C. Cary, editor, Avian Energetics. Chapman & Hall, New York, New York, USA.Google Scholar
- W. H. Karasov and I. D. Hume (1997), The vertebrate gastrointestinal system. Pages 407–480 in W. H. Dantzler, editor, Handbook of Physiology, Section 13: Comparative Physiology, Vol. 1. Oxford University Press, Oxford, New York, New York, USA.Google Scholar
- C. Martín ez del Rio, S. Cork, and W. H. Karasov (1994), Engineering and digestion: modeling gut function. Pages 25–53 in D. Chivers and P. Langer, editors, Food and Form and Function of the Mammalian Digestive Tract. Cambridge University Press, Cambridge, United Kingdom.Google Scholar
- W. A. Mitchell (2006), Adaptive dynamics, resource conversion efficiency, and species diversity. Proceedings, International Society of Dynamic Games, Tucson, Arizona, USA.Google Scholar
- T. B. Smith (1990), Comparative breeding biology of the two bill morphs of the black-bellied seedcracker. The Auk 107, 153–160.Google Scholar
- C. J. Whelan, J. S. Brown, K. A. Schmidt, B. B. Steele, and M. F. Willson (2000), Linking consumer-resource theory and digestive physiology: application to seasonal diet shifts. Evolutionary Ecology Research 2, 911–934.Google Scholar
- C. J. Whelan and K. A. Schmidt (2006), Food acquisition and processing. In Stephens, D. W., Ydenberg, R. and Brown, J. S., editors, Foraging. University of Chicago Press, Chicago, IL, USA.Google Scholar
- T. K. Wood, K. J. Tilmon, A. B. Shantz, C. K. Harris, and J. Pesek (1999), The role of host-plant fidelity in initiating insect race formation. Evolutionary Ecology Research 1, 317–332.Google Scholar