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

Abstract

Recent reviews of the adaptive hypotheses for animal responses to acclimation have highlighted the importance of distinguishing between developmental and adult (nondevelopmental) phenotypic plasticity. There has been little work, however, on separating the effects of developmental plasticity from adult acclimation on physiological traits. Therefore, we investigated the relative contributions of these two distinct forms of plasticity to the environmental physiology of adult tsetse flies by exposing developing pupae or adult flies to different temperatures and comparing their responses. We also exposed flies to different temperatures during development and reexposed them as adults to the same temperatures, to investigate possible cumulative effects. Critical thermal maxima were relatively inflexible in response to acclimation temperatures (21, 25, 29°C) with plasticity type accounting for the majority of the variation (49-67%, nested ANOVA). By contrast, acclimation had a larger effect on critical thermal minima with treatment temperature accounting for most of the variance (84-92%). Surprisingly little of the variance in desiccation rate could be explained by plasticity type (30-47%). The only significant effect of acclimation temperature on standard (resting) metabolic rate of adult flies was at 21°C, resulting in treatment temperature, rather than plasticity type, accounting for the majority of the variance (30-76%). This study demonstrates that the stage at which acclimation takes place has significant, though often different, effects on several adult physiological traits in G. pallidipes, and therefore that it is not only important to consider the form of plasticity but also the direction of the response and its significance from a life-history perspective.

Temperature and humidity acclimation increase desiccation resistance in the butterfly Bicyclus anynana

“…Kleynhans et al, 2014). For instance, Gibbs et al (1998), Terblanche et al (2005), Leinaas et al (2009), and Parkash & Ranga (2014) did not find an effect of acclimation temperature on water loss, whereas others did so (e.g., Hoffmann et al, 2005;Renault et al, 2005;Terblanche & Chown, 2006). Previous studies on insects revealed contradictory evidence (Chown et al, 2011;Kleynhans & Terblanche, 2011).…”

Phenotypic plasticity of desiccation resistance inGlossinapuparia: are there ecotype constraints on acclimation responses?

“…Among the major recent criticisms of tests of acclimation hypotheses or adaptive phenotypic plasticity in animal physiology are the lack of alternative hypotheses formulated and tested (Huey & Berrigan, 1996; Huey et al. , 1999), insufficient distinction between developmental and non‐developmental plasticity (Wilson & Franklin, 2002; Terblanche & Chown, 2006) and extreme test conditions outside ecologically realistic environmental conditions resulting in deleterious responses (Loeschke & Hoffmann, 2002). Our study does not suffer from these problems since we were able to address at least six distinct acclimation hypotheses (Table 1, Fig.…”

“…Furthermore, to our knowledge, no traits have been investigated for acclimation responses in the pupal life‐stage although some work on adult acclimation responses of G. pallidipes has been undertaken. These studies of adult physiology suggest that water balance and thermal tolerance are readily adjusted in response to different thermal regimes and that physiological responses might be stage‐ or age‐specific (Terblanche & Chown, 2006; Terblanche et al. , 2006; reviewed in Bowler & Terblanche, 2008).…”

“…This suggests that further research into intra‐ and inter‐specific physiological variation is an important avenue for understanding the evolution of Glossina . However, the latter studies were not designed to fully explore acclimation hypotheses (Terblanche & Chown, 2006) and the present study therefore addresses this major lacuna.…”

Tsetse flies: Genetics, evolution, and role as vectors

“…Little potential for evolutionary change was detected. Thus, phenotypic plasticity, not genetically determined, heritable, variation explained differences in physiological responses (Terblanche and Chown, 2006; Terblanche et al, 2006). …”