Everything that an animal does, from feeding to escaping predation, is influenced by underlying physiological traits. In this chapter, I focus on the insights gained by examining physiology in the context of lizard foraging mode. I will discuss apparent relationships between physiological traits and foraging mode and identify areas where we might expect to uncover explanatory correlates in the future. Understanding these relationships allows us to learn more about the evolution of lizard foraging and the related evolutionary processes and selective factors that act on underlying physiological components.
Many biologists have addressed the importance of evolutionary and comparative physiology (see, for example, Prosser, 1950; Diamond, 1993; Garland and Carter, 1994; Natochin and Chernigovskaya, 1997; Feder et al., 2000). Physiology can be rather broadly defined to include many integrated and hierarchical suborganismal traits that manifest in organismal function. An incomplete list of these traits and processes includes enzyme activity, membrane selectivity, establishment of ion gradients, ATP production, cellular respiration, lung ventilation, aerobic capacity, Q10 effects, lactate buffering, pH balance, sprint speed, digestive efficiency, and many other processes involved in homeostasis that ultimately contribute to the survival and reproduction (Darwinian fitness) of organisms (see Table 3.1 for a list of physiology-related traits likely to inform the study of foraging modes). Importantly, these myriad suborganismal traits do not work in isolation, nor are they typically involved in only one aspect of organismal function (see, for example, Bennett, 1989; Garland and Losos, 1994; Rose and Lauder, 1996b).