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Figure 1.4 Supercooling points (or crystallization temperatures) (mean ± SE) for gall wasp (Hymenoptera, Cynipidae) prepupae overwintering above (open square) and below (filled circles) the snow at a single site (Sudbury, Ontario, Canada).

Source: Modified from Williams et al. (2002).

of the planet. For example, survival of low temperatures in insects is mediated by polyhydric alcohols and antifreeze proteins (Denlinger and Lee 1998), but not by molar quantities of salts or by the development of a subcutaneous fat layer (the latter being a solution that is open to and has been used by a variety of mammals). 4. Large-scale, geographic variation in traits can be detected, despite all the variation associated with feeding status, season, age, and taxon. For example, water loss rates vary with total rainfall (Addo-Bediako et al. 2001), extreme lower lethal limits decline with proximity to the poles (Addo-Bediako et al. 2000), and there is a weak, though significant, negative relationship between standard metabolic rate and environmental temperature (Fig. 1.5). This variation would not be detectable if insects showed a bewildering, non-understandable array of responses to the environment.

Table 1.1 Distribution of variance in supercooling point (SCP) of freezing tolerant and freeze intolerant insects, lower lethal temperature (LLT) of freezing tolerant insects, upper lethal temperature (ULT), critical thermal maximum (CTmax), metabolic rate, and water loss rate in insects

Variable

Order

Family

Genus

Species

Freeze intolerant SCP

18.68*

32.47**

33.14**

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