DOI: 10.5061/dryad.3fb854n
title: Data from: Evolution of thermal tolerance in multifarious environments

description: Species extinction rates are many times greater than the direst
 predictions made two decades ago by environmentalists, largely because of
 human impact. Major concerns are associated with the predicted higher
 recurrence and severity of extreme events, such as heat waves. Although
 tolerance to these extreme events is instrumental to species survival,
 little is known whether and how it evolves in natural populations, and to
 what extent it is affected by other environmental stressors. Here, we
 study physiological and molecular mechanisms of thermal tolerance over
 evolutionary times in multifarious environments. Using the practice of
 ‘resurrection ecology’ on the keystone grazer Daphnia magna, we quantified
 genetic and plastic differences in physiological and molecular traits
 linked to thermal tolerance in historical and modern genotypes of the same
 population. This population experienced an increase in average temperature
 and occurrence of heat waves, in addition to dramatic changes in water
 chemistry, over five decades. On genotypes resurrected across the five
 decades, we measured plastic and genetic differences in CTmax, body size,
 Hb content and differential expression of four heat shock proteins after
 exposure to temperature as single stress and in combination with food
 levels and insecticide loads. We observed evolution of the critical
 thermal maximum and plastic response in body size, HSP expression and Hb
 content over time in a warming only scenario. Molecular and physiological
 responses to extreme temperature in multifarious environments were not
 predictable from the response to warming alone. Underestimating the effect
 of multiple stressors on thermal tolerance can lead to wrong estimates of
 species evolvability and persistence.
description: Total haemoglobin
 contentTotal haemoglobin
 content measured in µmol/L in the 30 genotypes of Daphnia magna studied
 here at the control temperature (20C) and after exposure to hyper-thermal
 stress (30C). Genotype ID, population ID, average Hb content across three
 replicates and log2 fold change of total Hb content between the two
 experimental temperatures are shown. The Hb data are From Cambronero et
 al. 2017.Cambronero_etal_Hb.xlsxCTmax and body sizeCTmax and body size measured on the 30 genotypes resurrected from Lake Ring. Data were collected after exposure to temperature by itself (CGE1) and in combination with either food levels (CGE2) or insecticide Carbaryl loads (CGE3). The experimental temperatures are: 18C and 24C. The two nutrient levels are: 0.2 mg C/L and 2.4 mg C/L. The two concentrations of Carbaryl are: 4 µg/L and 10 µg/L. Empty cells are missing data. The data on body size are from Cambronero et al., in review in Scientific Reports.Cambronero_etal_CTmax_bodysize.xlsxHSPs expressionHSPs log2 fold change normalized gene expression of four heat shock proteins (HSP20, HSP60, HSP70, HSP90). The expression of these proteins was measured on genotypes exposed to temperature ramping (TR) treatment immediately after the completion of the common garden experiments conducted by Cambronero et al. (in review) and on the same genotypes not exposed to TR. These included exposure to temperature as single stress (Warming), temperature combined with food limitation (Warming and food limitation), and temperature combined with the insecticide Carabryl (Warming and insecticide). Empty cells indicate missing values.Cambronero_etal_HSP expression.csv