title: Reversibility of developmental heat and cold plasticity is asymmetric and has long-lasting consequences for adult thermal tolerance.
abstract: 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 senescence-associated 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.
authors.affiliation: Department of Bioscience, Aarhus University, Ny Munkegade 116, Aarhus DK-8000, Denmark stsl@bios.au.dk.
authors.forename: Stine
authors.identifier: 0000-0001-9974-0014
authors.initials: S
authors.lastname: Slotsbo
authors.affiliation: Department of Bioscience, Aarhus University, Ny Munkegade 116, Aarhus DK-8000, Denmark.
authors.forename: Mads F
authors.initials: MF
authors.lastname: Schou
authors.affiliation: Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, Aalborg DK-9220, Denmark.
authors.forename: Torsten N
authors.initials: TN
authors.lastname: Kristensen
authors.affiliation: Department of Bioscience, Aarhus University, Ny Munkegade 116, Aarhus DK-8000, Denmark.
authors.forename: Volker
authors.initials: V
authors.lastname: Loeschcke
authors.affiliation: Department of Bioscience, Aarhus University, Ny Munkegade 116, Aarhus DK-8000, Denmark.
authors.forename: Jesper G
authors.initials: JG
authors.lastname: Sørensen
mesh_terms: D000064:Acclimatization / Q000502:physiology; D000375:Aging / Q000502:physiology*; D000818:Animals; D003080:Cold Temperature; D004331:Drosophila melanogaster / Q000254:growth & development* / Q000502:physiology*; D006358:Hot Temperature; D000071436:Thermotolerance / Q000502:physiology*; D013997:Time Factors
keywords: Climate change; Cold tolerance; Drosophila; Heat tolerance; Longevity; Phenotypic plasticity