Metabolic scopes for survival

Figure 2.5. Metabolic scope for activity (defined as the difference between maximum metabolic rate and the SMR) and the metabolic scope for survival (defined as the difference between the SMR and maximally suppressed metabolic rates). Hummingbird estimates shown for normothermic conditions and for torpor metabolic rates (the latter gives the full biological scope for activity). Suppressed metabolic rates for the aquatic organisms assume temperatures of about 20°C (except for the pumpkinseed, where suppressed metabolism occurs during overwintering hibernation at about 4°C). (Modified from Hochachka (1990.)...

This high elevation plant diversity harbors extended animal communities which have not been sufficiently well studied. However, in as much as cross pollination and non-wind seed dispersal are fundamental mechanisms for plant species survival, this fauna is of crucial importance to vascular plant life. Although animal life is beyond the scope of the present chapter, the interested reader might find some specific reports instruetive (e.g. Pefaur and Duellman, 1980 Pefaur and Diaz de Pascual, 1985 Vuilleumier, 1986 Hoffstetter, 1986 Cei, 1986 Reig, 1986 Holloway, 1986 Villwock, 1986 Durant et al., 1994 Diaz et al., 1997). As far as arthropods and their influence in secondary plant metabolism, their species diversity has been observed to decline with elevation in some places (e.g. Fleishman et al., 1998). Some exceptions exist as the case of mite s abundance and species diversity in the Appalachians illustrates (Lamoncha and Crossley, 1998). However, more important than species richness to herbivory pressure is the number of individuals forming a herbivore population, a subject that requires further attention in high elevations before a clear picture on their influence on secondary plant metabolism may be assessed properly. 

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