Abstract

Thermal performance curves (TPCs) compute the effects of temperature on the performance of ectotherms and are frequently used to predict the effect of environmental conditions and currently, climate change, on organismal vulnerability and sensitivity. Using Drosophila melanogaster as an animal model, we examined how different thermal environments affected the shape of the performance curve and their parameters. We measured the climbing speed as a measure of locomotor performance in adult flies and tested the ontogenetic and transgenerational effects of thermal environment on TPC shape. Parents and offspring were reared at 28 ± 0ºC (28C), 28 ± 4ºC (28V), and 30 ± 0ºC (30C). We found that both, environmental thermal variability (28V) and high temperature (30C) experienced during early ontogeny shaped the fruit fly TPC sensitivity. Flies reared at variable thermal environments shifted the TPC to the right and increased heat tolerance. Flies held at high and constant temperature exhibited lower maximum performance than flies reared at the variable thermal environment. Furthermore, these effects were extended to the next generation. The parental thermal environment had a significative effect on TPC and its parameters. Indeed, flies reared at 28V whose parents were held at a high and constant temperature (30C) had a lower heat tolerance than F1 of flies reared at 28C or 28V. Also, offspring of flies reared at variable thermal environment (28V) reached the maximum performance at a higher temperature than offspring of flies reared at 28C or 30C. Consequently, since TPC parameters are not fixed, we suggest cautiousness when using TPCs to predict the impact of climate change on natural populations.

Highlights

  • To a large extent the susceptibility and vulnerability of ectotherms to climate change has been assessed through the study of thermal perfor‐ mance curves (TPCs) which characterize the relationship between performance or fitness and body temperature (Sinclair et al, 2016)

  • Third generation adult flies from the stock were randomly assigned to one of three thermal treatments set based on the limits of fruit fly egg viability: (a) moderate mean and no variance (28 ± 0°C, “28 ± 0oC (28C)”), (b) moderate mean and high variance (28 ± 4°C, “28V”), and (c) high mean and no variance (30 ± 0°C, “30 ± 0oC (30C)”)

  • Our key finding was that the environmental thermal variability and high and constant temperature experienced during early ontog‐ eny shape the thermal performance curve

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Summary

| INTRODUCTION

The transgenerational transfer called parental effects (Badyaev & Uller, 2009), transgenerational plasticity (Marshall & Uller, 2007) and transgenerational memory (Molinier, Ries, Zipfel, & Hohn, 2006) is used to describe the trans‐ mission of traits, factors, and/or information that induces pheno‐ typic changes from one generation to the (Ho & Burggren, 2010) Such effects could enable offspring receive information early during the development and modify the phenotype adapta‐ tively according to parental information to best respond to their environment (Engqvist & Reinhold, 2016; Klosin, Casas, Hidalgo‐ Carcedo, Vavouri, & Lehner, 2017; Mousseau & Fox, 1998; Salinas, Brown, Mangel, & Munch, 2013; Schmalhausen, 1938; Young & Badyaev, 2007). We hy‐ pothesized that the offspring of parents in the high temperature and variable temperature treatments would have increased thermal tol‐ erance compared to controls despite not having directly experienced these conditions

| MATERIALS AND METHODS
| DISCUSSION
CONFLICT OF INTEREST
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