Resistance to temperature extremes in sub-Antarctic weevils: interspecific variation, population differentiation and acclimation

Abstract

Much of the work on the responses of terrestrial arthropods to high and low temperatures has been done on model organisms such as Drosophila . However, considerable variation in thermotolerance is partitioned at the family level and above, raising questions about the broader applicability of this work to other taxa. Here we investigate resistance to high and low temperatures, following different temperature treatments, in ten species and 31 populations of weevils found on sub-Antarctic Heard Island and Marion Island, which have substantially different climates. In these weevils there is considerable interspecific and among-population variation in critical thermal minimum (CTmin) and critical thermal maximum (CTmax), but most of this variation in critical limits can be ascribed to phenotypic plasticity. We find no relationship between CTmin and CTmax at the species level, and this is true also of populations and of responses to the temperature treatments. In general, plastic (acclimation) changes in CTmin are larger than those in CTmax. Our data therefore provide support for the idea that resistance to heat and to cold are decoupled in terrestrial arthropods. Furthermore, our results suggest that investigations of physiological limits to species borders should incorporate the effects of phenotypic plasticity on physiological capabilities. continuous expression or persistence of the 72kDa heatshock protein. Journal of Insect Physiology 38: 603-609. Zatsepina OG, Velikodvorskaia VV, Molodtsov VB, Garbuz D, Lerman DN, Bettencourt BR, Feder ME, Evgenev MB. 2001. A Drosophila melanogaster strain from sub-equatorial Africa has exceptional thermotolerance but decreased Hsp70 expression. Journal of Experimental Biology 204: 1869-1881.

The relative contributions of developmental plasticity and adult acclimation to physiological variation in the tsetse fly, Glossina pallidipes (Diptera, Glossinidae)

“…In the case of thermal tolerances, acclimation effects were more pronounced for T crit,min than for T crit,max , as has been found in several other studies examining acclimation (Klok and Chown, 2003;Slabber and Chown, 2005) or acclimatization (Hoffmann et al, 2005b) effects on thermal limits. Although a more pronounced acclimation effect on lower than on upper limits is not universal [e.g.…”

“…Nonetheless, strong opposing responses to high and low temperature treatments for lower thermal limits have been found in several other studies, though typically these examined acclimation effects on a single stage only (e.g. Ayrinhac et al, 2004;Hoffmann et al, 2005b;Klok and Chown, 2003;Slabber and Chown, 2005;Terblanche et al, 2005b;Zeilstra and Fischer, 2005). Likewise, asymmetric or threshold effects of treatment temperature have previously been recorded for T crit,max (Hoffmann et al, 2005b;Klok and Chown, 1998;Slabber and Chown, 2005), metabolic rate (Hoffmann, 1985;Terblanche et al, 2005a) and desiccation rate (Rourke, 2000).…”

Survival of rapidly fluctuating natural low winter temperatures by High Arctic soil invertebrates

“…Beetles of the family Curculionidae are one of the dominant Coleoptera families in the High Arctic fauna (Coulson et al, 2014), as is also the case on the sub-Antarctic islands (Chown, 1992;Convey, 2007). These are freeze-avoiding, but in the latter region show relatively high critical thermal minima and limited survival below their freezing point (van der Merwe et al, 1997;Klok and Chown, 2003), which reflect closely the stable cool climates of the sub-Antarctic islands. No comparable data are available for Arctic or other cold environment weevils from the Northern Hemisphere, although a recent study of woodland invasive weevils similarly reported a low extent of freezing tolerance (Coyle et al, 2011).…”

Metabolism of the sub-Antarctic caterpillar Pringleophaga marioni during cooling, freezing and thawing

“…For example, Gibert and Huey (2001) found that the chill-coma temperature of Drosophila differed between species and populations from different latitudes (suggestive of natural selection) and could be modified within those populations by developmental temperature (indicative of developmental plasticity). Klok and Chown (2003) found that the CTmin of sub-Antarctic weevils (Ectemnorhinus) responded to acclimation, with higher acclimation temperatures resulting in significantly higher CTmin values. Activity of the Na + /K + -ATPase pump may be modulated to reduce energy expenditure in response to heat shock and anoxia (Hochachka et al, 1996;Wu et al, 2002), and there is a variety of isomeric sodium pumps produced by insects under different environmental conditions, stages of development and tissues (Emery et al, 1998).…”