Physiological Ecology of Nutrient Acquisition in Animals

by

Michele M. Skopec

• LAST REVIEWED: 25 February 2014
• LAST MODIFIED: 25 February 2014
• DOI: 10.1093/obo/9780199830060-0070

Introduction

Physiological ecologists are interested in how animals have adapted physiologically to their environments and the ecological consequences of such adaptations. A focus area of physiological ecology seeks to understand how animals obtain the needed nutrients to survive, grow, and reproduce. The first step in obtaining needed nutrients is to procure them, and the series of behaviors and adaptations that accompany procurement of foodstuffs is covered in the articles Optimal Foraging and Implications of Foraging Behavior. Once food has been consumed, the nutrients need to be digested and then absorbed across the gastrointestinal lining before they can be used by the animal for cellular processes. To digest and absorb food, animals rely on a series of specialized organs or chambers in their gastrointestinal tract containing enzymes that convert the consumed macromolecules into absorbable units and transporters capable of moving the nutrients across the gut wall. Animals consume a wide variety of foodstuffs, some of which are highly digestible and easily broken down and absorbed, for example carnivores, and some of which are refractory and resist digestion and therefore absorption, for example wood-eating termites. Theory predicts that an animal’s gastrointestinal tract, enzyme production, transporter function, and presence of symbionts will match the chemical nature of their diet. But what happens in animals that undergo long periods of fasting or diet switch during developmental stages or seasonally? If animals need morphological and/or functional plasticity in their gastrointestinal systems, how is such plasticity accomplished? These are just a small sample of some of the questions researchers in the field of physiological ecology of nutrient acquisition are studying. Students or scientists interested in pursuing research in the physiological ecology of nutrient acquisition will need to draw from the larger fields of physiology, biochemistry, nutrition, and ecology.

General Overviews

Karasov and Martinez del Rio 2007 is a physiological ecology text that is focused on nutrient acquisition and is a must-read for those interested in the field. For a vertebrate-only focus, interested readers should try Starck and Wang 2005. Karasov 2011 and Karasov, et al. 2011 are two recent review papers that give overviews of the current status of the field. Barboza, et al. 2010 is an overview of some of the current research topics in the field. A comprehensive overview of the field of physiological ecology of vertebrates can be gained by looking through McNab 2002; this treatise on the subject would be helpful for readers interested in how nutrient acquisition fits into the broader field of physiological ecology. For readers more interested in invertebrates, Chown and Nicolson 2004 is an excellent text on insect physiological ecology that contains an entire section on nutritional physiology and ecology of insects. The related field of nutritional ecology is outlined by Simpson and Raubenheimer 2012.

• Barboza, Perry S., Albert Bennett, Jean-Herve Lignot, et al. 2010. Digestive challenges for vertebrate animals: Microbial diversity, cardiorespiratory coupling, and dietary specialization. Physiological and Biochemical Zoology 83.5: 764–774.

  DOI: 10.1086/650472

  Prepared as an overview of the subjects covered in the symposium “Molecules to Migration: Pressures of Life” at the Fourth International Conference in Africa for Comparative Physiology and Biochemistry. Three active research fields are nicely summarized. Good starting point for anyone unfamiliar with any of the covered topics.

• Chown, Steven L., and Sue Nicolson. 2004. Insect physiological ecology: Mechanisms and patterns. Oxford: Oxford Univ. Press.

  DOI: 10.1093/acprof:oso/9780198515494.001.0001

  Contains section on the nutritional physiology and ecology of insects with numerous figures and examples from the literature. Could be used as a text for an upper-division undergraduate or graduate-level class on insect physiological ecology as well as serve as a desk reference for those already in the field.

• Karasov, William H. 2011. Digestive physiology: A view from molecules to ecosystem. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology 301:R276–R284.

  An invited review that chronicles William Karasov’s thirty-year history studying nutrient acquisition in animals. While many of the examples are avian, William Karasov’s approach of scaling from the molecular mechanisms to ecosystem-level effects may be illustrative of what approaches can be used in other animal groups.

• Karasov, William H., and Carlos Martinez del Rio. 2007. Physiological ecology: How animals process energy, nutrients, and toxins. Princeton, NJ: Princeton Univ. Press.

  An essential text for anyone interested in the physiological ecology of nutrient acquisition. While the book is broadly named as a physiological ecology text, the subtitle reveals the true focus of the text. Examples from both vertebrates and invertebrates abound; literature is well summarized and essential research techniques are discussed.

• Karasov, William H., Carlos Martinez del Rio, and Enrique Caviedes-Vidal. 2011. Ecological physiology of diet and digestive systems. Annual Review of Physiology 73:69–93.

  DOI: 10.1146/annurev-physiol-012110-142152

  A review of new and cutting-edge studies in the field with a significant focus on the role of microbial symbionts in nutrient acquisition. Areas of potential study are also outlined.

• McNab, Brian K. 2002. The physiological ecology of vertebrates: A view from energetics. Ithaca, NY: Cornell Univ. Press.

  Informative text for those interested in understanding the role of nutrient acquisition in the broader field of physiological ecology. Best suited as a graduate-level text or desk reference. Contains many examples and figures from the literature. The text, as implied in the title, does focus solely on vertebrates.

• Simpson, Stephen J., and David Raubenheimer. 2012. The nature of nutrition: A unifying framework from animal adaptation to human obesity. Princeton, NJ: Princeton Univ. Press.

  Contains a detailed discussion of how the geometric framework can be used by ecologists to understand the nutritional needs of wild organisms. Contains examples from both invertebrates and vertebrates. Many figures from the literature are present.

• Starck, J. Matthias, and Tobias Wang, eds. 2005. Physiological and ecological adaptations to feeding in vertebrates. Enfield, NH: Science Publishers.

  This multi-author text combines the expertise of scientists from the field and contains many useful diagrams and figures. The examples are limited to vertebrates. Most suitable to scientists in the field or graduate students.