Environmental Effects on Temperature Stress Resistance in the Tropical Butterfly Bicyclus Anynana

In many ectotherms, exposure to high temperatures can improve subsequent tolerance to higher temperatures. However, the differential effects of single, repeated or continuous exposure to high temperatures are less clear. We measured the effects of single heat shocks and of diurnally fluctuating or constant rearing temperatures on the critical thermal maximum (CT max ) for final instar larvae of Manduca sexta. Brief (2 h) heat shocks at temperatures of 35°C and above significantly increased CT max relative to control temperatures (25°C). Increasing mean temperatures (from 25 to 30°C) or greater diurnal fluctuations (from constant to ±10°C) during larval development also significantly increased CT max . Combining these data showed that repeated or continuous temperature exposure during development improved heat tolerance beyond the effects of a single exposure to the same maximum temperature. These results suggest that both acute and chronic temperature exposure can result in adaptive plasticity of upper thermal limits.

Section: Resultsmentioning

confidence: 99%

Plasticity of upper thermal limits to acute and chronic temperature variation in Manduca sexta larvae

Kingsolver

MacLean

et al. 2016

“…Given the adaptive significance of a continuous alignment of the phenotype to the environment as well as the associated costs, an understanding of the detailed adult acclimation response (capacity and rate of acclimation) and its dependence on the developmental environment has received surprisingly little attention. Most noteworthy is the work on adult cold and heat acclimation in butterflies developed at different temperatures (Fischer et al, 2010;Geister and Fischer, 2007;Zeilstra and Fischer, 2005).…”

Section: Introductionmentioning

confidence: 99%

Reversibility of developmental heat and cold plasticity is asymmetric and has long lasting consequences for adult thermal tolerance

Slotsbo

Schou

Kristensen

et al. 2016

The ability of insects to cope with stressful temperatures through adaptive plasticity has allowed them to thrive under a wide range of thermal conditions. Developmental plasticity is generally considered to be a non-reversible phenotypic change, e.g. in morphological traits, while adult acclimation responses are often considered to be reversible physiological responses. However, physiologically mediated thermal acclimation might not follow this general prediction. We investigated the magnitude and rate of reversibility of developmental thermal plasticity responses in heat and cold tolerance of adult flies, using a full factorial design with two developmental and two adult temperatures (15 and 25°C). We show that cold tolerance attained during development is readily adjusted to the prevailing conditions during adult acclimation, with a symmetric rate of decrease or increase. In contrast, heat tolerance is only partly reversible during acclimation and is thus constrained by the temperature during development. The effect of adult acclimation on heat tolerance was asymmetrical, with a general loss of heat tolerance with age. Surprisingly, the decline in adult heat tolerance at 25°C was decelerated in flies developed at low temperatures. This result was supported by correlated responses in two senescenceassociated traits and in accordance with a lower rate of ageing after low temperature development, suggesting that physiological age is not reset at eclosion. The results have profound ecological consequences for populations, as optimal developmental temperatures will be dependent on the thermal conditions faced in the adult stage and the age at which they occur.

“…Against this background we here explore the sensitivity of a tropical ectotherm, the butterfly Bicyclus anynana (Butler 1879), to experimentally simulated heat waves using ecologically realistic diurnal temperature cycles. This species is eminently suitable for such a study as it inhabits environments with alternating warm-wet and cool-dry seasons, and shows strong temperature-mediated plasticity in an array of traits such that it might be relatively well equipped to buffer detrimental effects of increasing temperatures (Fischer et al, 2003;Fischer et al, 2010;Franke et al, 2012). This fruit-feeding butterfly is distributed from southern Africa to Ethiopia (Larsen, 1991).…”

Section: Introductionmentioning

confidence: 99%

Strong negative effects of simulated heat waves in a tropical butterfly

Fischer

Klockmann

Reim

2014

Self Cite

Climate change poses a significant challenge to all natural systems on Earth. Especially increases in extreme weather events such as heat waves have the potential to strongly affect biodiversity, though their effects are poorly understood because of a lack of empirical data. Therefore, we here explore the sensitivity of a tropical ectotherm, which are in general believed to have a low warming tolerance, to experimentally simulated climate change using ecologically realistic diurnal temperature cycles. Increasing the mean temperature permanently by 3°C had mostly minor effects on developmental traits in the butterfly Bicyclus anynana. Simulated heat waves (strongly elevated temperatures for some time though retaining the same overall temperature mean), in contrast, caused strong negative effects by prolonging development time (by up to 10%) and reducing body mass (−21%), especially when combined with reduced relative humidity. Detrimental effects were carried over into the adult stage, diminishing subsequent performance. Most strikingly, higher temperatures suppressed adult immune function (haemocytes: −54%, lysozyme activity: −32%), which may potentially change the way species interact with antagonists. Heat waves thus reduced fitness parameters by 10-25% for development time and body mass and by up to 54% for immune parameters even in this plastic and widespread butterfly, exemplifying the potentially dramatic impact of extreme weather events on biodiversity.