To fully comprehend and predict the impact of drivers of global change such as climate warming and pollution, integrated multi‐trait approaches are needed. As organismal traits are often correlated, responses to stressors are expected to induce coordinated changes in many traits. A promising framework to study this is the pace of life syndrome (POLS), which predicts the integration of life history, behavioral, and physiological traits along a fast‐slow continuum. Using an integrative multi‐trait approach, we evaluated the presence of a POLS both within and across latitudes and how POLS patterns are affected by warming and metal pollution. We studied this in Ischnura elegans damselfly larvae of replicated low‐ and high‐latitude populations that strongly differ in voltinism (three to four generations per year vs. one generation every two years) reared in a common‐garden experiment at two temperatures. Across latitudes, life history, behavior, and physiology covaried in accordance with the POLS, with the fast‐paced low‐latitude damselflies characterized by a fast growth rate, high activity, and more explorative and risk‐taking behavior, fast metabolic rate, and low investment in immune function (activity of phenoloxidase). This fast POLS strategy was associated with a higher sensitivity to metal exposure and a higher vulnerability to predation. Warming caused opposite responses between the latitudes consistent with differential thermal adaptation in growth rate, behavior, and oxidative stress parameters. Despite this, damselflies of both latitudes showed a consistent pattern in phenotypic correlations among traits that, moreover, was not affected by warming and metal exposure. Within latitudes, there was no full support for the POLS. More active larvae were more explorative and risk taking, which aligned with the fast‐slow life history axis, but less strong than at the across‐latitude level. Physiological traits were also integrated within latitudes, yet there was no unambiguous coupling with the fast‐slow life history continuum. The consistent syndrome structure, if underpinned by genetic correlations, may restrict the independent evolution of individual traits, yet may not necessarily constrain adaptive evolution of integrated trait sets. This is because the covariance pattern was to a large extent similar across latitudes and within latitudes, suggesting adaptive trait integration guiding adaptive evolution of trait sets along the fast‐slow continuum.

The pace-of-life syndrome (POLS) hypothesis integrates covariation of life-history traits along a fast-slow continuum and covariation of behavioural traits along a proactive-reactive personality continuum. Few studies have investigated these predicted life-history/personality associations among species and between sexes. Furthermore, whether and how contaminants interfere with POLS patterns remains unexplored. We tested for covariation patterns in life history and in behaviour, and for life-history/personality covariation among species, among individuals within species and between sexes. Moreover, we investigated whether pesticide exposure affects covariation between life history and behaviour and whether species and sexes with a faster POLS strategy have a higher sensitivity to pesticides. We reared larvae of four species of Ischnura damselflies in a common garden experiment with an insecticide treatment (chlorpyrifos absent/present) in the final instar. We measured four life-history traits (larval growth rate during the pesticide treatment, larval development time, adult mass and life span) and two behavioural traits (larval feeding activity and boldness, each before and after the pesticide treatment). At the individual level, life-history traits and behavioural traits aligned along a fast-slow and a proactive-reactive continuum, respectively. Species-specific differences in life history, with fast-lived species having a faster larval growth and development, a lower mass at emergence and a shorter life span, suggested that time constraints in the larval stage were predictably driving life-history evolution both in the larval stage and across metamorphosis in the adult stage. Across species, females were consistently more slow-lived than males, reflecting that a large body size and a long life span are generally more important for females. In contrast to the POLS hypothesis, there was only little evidence for the expected positive coupling between life-history pace and proactivity. Pesticide exposure decreased larval growth rate and affected life-history/personality covariation in the most fast-lived species. Our study supports the existence of life-history and behavioural continua with limited support for life-history/personality covariation. Variation in digestive physiology may explain this decoupling of life history and behaviour and provide valuable mechanistic insights to understand and predict the occurrence of life-history/personality covariation patterns.

Summary1. Freshwater ecosystems are especially vulnerable to climate change and pollution. One key challenge for aquatic toxicology is to determine and manage the combined effects of temperature increase and contaminants across species' ranges. 2. We tested how thermal adaptation and life-history evolution along a natural temperature gradient influence the vulnerability of an aquatic insect to a pesticide under global warming. We applied a space-for-time substitution approach to study the effect of warming on the vulnerability of Ischnura elegans damselfly larvae to the pesticide chlorpyrifos in a common garden warming experiment (20 and 24°C) with replicated populations from three latitudes spanning >1500 km in Europe. 3. Chlorpyrifos was more toxic to damselfly larvae at the higher temperature: mortality only occurred at 24°C and the reductions in growth rate were stronger at 24°C. This could partly be explained by parallel reductions in food intake but not by the activities of two widespread enzymatic biomarkers, glutathione S-transferase (GST) and acetylcholinesterase (AChE). 4. There was some evidence that the increased toxicity of the high chlorpyrifos concentration at 24°C was stronger in terms of growth reduction in the faster-growing larvae from the low-latitude populations. This is consistent with energy allocation trade-offs between growth rate and pesticide tolerance, but suggests that local thermal adaptation does not play a role in coping with pesticide stress. 5. Synthesis and applications. Damselfly larvae from populations in lower latitudes were more vulnerable to a common pesticide at higher temperatures and pesticide concentrations, whereas evidence for the influence of local thermal adaptation on the vulnerability of larvae was weak. These results emphasize the need for spatially explicit bioassessment and conservation tools. Management practices aimed at mitigating pesticide run-off into aquatic ecosystems are particularly important in agricultural areas at low latitudes.

Summary Despite the strong impact of ultraviolet (UV) radiation on invertebrates, it is unknown whether it affects immune function across metamorphosis. More generally, the mechanisms on how larval stressors bridge metamorphosis and shape adult fitness in animals with a complex life cycle remain poorly understood. We studied whether cuticular melanin content is upregulated under UV exposure in the larval stage of the damselfly Coenagrion puella and whether this is traded off across metamorphosis against a key component of the invertebrate immune response, the melanotic encapsulation response, in the adult stage. Larvae exposed to UV increased the melanin content in their exoskeleton and metamorphosed later and at a smaller mass than animals reared without UV. Across metamorphosis, this was associated with a reduced melanotic encapsulation response, thereby constituting the first proof for a UV‐driven impaired immune response in an invertebrate. The demonstrated costs of UV exposure in terms of age and mass at metamorphosis and reduced adult immune response likely translate into reduced adult fitness. Path analysis indicated that the immunosuppressive property of larval UV exposure was not mediated by age and mass at metamorphosis, but instead that the adult immune response was traded off against larval cuticular melanin investment. Melanin‐based trade‐off across metamorphosis provides a new pathway by which effects of larval stressors are carried over to the adult stage and thereby advances our understanding of the still largely enigmatic mechanisms of carryover effects of larval stressors across metamorphosis. Given the mechanistic basis, this carryover effect of larval UV exposure on adult immune function is expected to be general and may constitute a widespread and important cost of UV exposure in invertebrates.

The increase in temperature as consequence of the recent global warming has been reported to generate new ice-free areas in the Antarctic continent, propitiating the colonization and spread of plant populations. Consequently, antarctic vascular plants have been observed extending their southern distribution. But as the environmental conditions toward southern localities are progressively far apart from these species' physiological optimum, the colonization of new sites and ecophysiological responses could be decreased. However, if processes of local adaptation are the main cause of the observed southern expansion, those populations could appear constrained to respond positively to the expected global warming. Using individuals from the southern tip of South America, the South Shetland Islands and the Antarctic Peninsula, we assess with a long term experiment (3 years) under controlled conditions if the responsiveness of Colobanthus quitensis populations to the expected global warming, is related with their different foliar traits and photoprotective mechanisms along their latitudinal gradient. In addition, we tested if the release of the stress condition by the global warming in theses cold environments increase the ecophysiological performance. For this, we describe the latitudinal pattern of net photosynthetic capacity, biomass accumulation, and number of flowers under current and future temperatures-by warming-respective to each site of origin after three growing seasons. Overall, was showed a clinal trend was found in the foliar traits and photoprotective mechanisms in the evaluated C. quitensis populations. On the other hand, an asymmetric response to warming was observed for southern populations in all ecophysiological traits evaluated, suggesting that low temperature is limiting the performance of C. quitensis populations, mainly in those from southern. Our results suggest that under a global warming scenario those plant populations that inhabiting cold zones at high latitudes could be improved in their ecophysiological PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.3069v1 | CC BY 4.0 Open Access | rec performance, enhancing the size of populations or their spread. PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.3069v1 | CC BY 4.0 Open Access | rec ABSTRACT 22 The increase in temperature as consequence of the recent global warming has been reported to generate 23 new ice-free areas in the Antarctic continent, propitiating the colonization and spread of plant 24 populations. Consequently, Antarctic vascular plants have been observed extending their southern 25 distribution. But, as the environmental conditions toward southern localities become progressively more 26 departed from the species' physiological optimum, the ecophysiological responses and survival to the 27 expected global warming could be reduced. However, if processes of local adaptation are the main cause 28 of the observed southern expansion, those populations could appear constrained to respond positively to 29 the expec...