Thermal evolution of life history and heat tolerance during range expansions toward warmer and cooler regions

Abstract

Species' range edges are expanding to both warmer and cooler regions. Yet, no studies directly compared the changes in range-limiting traits within the same species during both types of range expansions. To increase our mechanistic understanding of range expansions, it is crucial to disentangle the contributions of plastic and genetic changes in these traits. The aim of this study was to test for plastic and evolutionary changes in heat tolerance, life history, and behavior, and compare these during range expansions toward warmer and cooler regions. Using laboratory experiments we reconstructed the thermal performance curves (TPCurves) of larval life history (survival, growth, and development rates) and larval heat tolerance (CTmax) across two recent range expansions from the core populations in southern France toward a warmer (southeastern Spain) and a cooler (northwestern Spain) region in Europe by the damselfly Ischnura elegans. First-generation larvae from field-collected mothers were reared across a range of temperatures (16°-28°C) in incubators. The range expansion to the warmer region was associated with the evolution of a greater ability to cope with high temperatures (increased mean and thermal plasticity of CTmax), faster development, and, in part, a faster growth, indicating a higher time constraints caused by a shorter time frame available for larval development associated with a transition to a greater voltinism. Our results thereby support the emerging pattern that plasticity in heat tolerance alone is inadequate to adapt to new thermal regimes. The range expansion to the cooler region was associated with faster growth indicating countergradient variation without a change in CTmax. The evolution of a faster growth rate during both range expansions could be explained by a greater digestive efficiency rather than an increased food intake. Our results highlight that range expansions to warmer and cooler regions can result in similar evolutionary changes in the TPCurves for life history, and no opposite changes in heat tolerance.

Climate change alters plant–herbivore interactions

“…In the longer term, rapid generation times and intraspecific genetic variation in heat resistance could result in rapid adaptation of thermal performance curves as temperatures continue to increase (Muñoz‐Valencia et al ., 2016; Ranga et al ., 2017). We can turn to a non‐herbivorous system as an example Carbonell & Stoks (2020) recently documented evolutionary changes in the thermal performance curves of the European damselfly ( Ischnura elegans ) during its range expansion toward warmer regions. Yet examples of the evolution of thermal performance curves under climate change are rare (Tüzün & Stoks, 2018), and more such studies are needed in herbivores , as it remains unclear whether standing genetic variation for heat resistance is adequate for sustained responses to selection (Kellermann et al ., 2012; Kellermann & van Heerwaarden, 2019).…”

Evolution of cold tolerance and thermal plasticity in life history, behaviour and physiology during a poleward range expansion

“…Ischnura elegans is rapidly expanding its range northwards in response to global warming (Carbonell & Stoks, 2020;Dudaniec et al, 2018). It has, for example, extended its northern range limit more than 140 km in Scotland since 1960, and ~300 km in Sweden since 2000 (Hickling et al, 2005;Lancaster et al, 2015).…”

“…While trait changes during range expansion have been recorded mainly in the dispersive adult stage (reviews in Chuang & Peterson, 2016;Hill et al, 2011), trait changes in the non-dispersive larval stage have been studied much less (but see Carbonell & Stoks, 2020;Phillips, 2009;Therry, Nilsson-Örtman, et al, 2014). Nevertheless, the larval stage can be very important for range expansion as larval life-history traits may be key factors of population dynamics.…”

Avoiding a conservation pitfall: Considering the risks of unsuitably hot bat boxes

“…An organism's thermal tolerance—that is, the temperature range within which it can maintain normal operative bodily function—may influence its behavior, distribution, and survival across a range of environmental conditions (Borowik, Ratkiewicz, Maślanko, Duda, & Kowalczyk, 2020; Carbonell & Stoks, 2020; Helmuth & Hofmann, 2001; Sunday, Bates, & Dulvy, 2012). When ambient temperatures exceed thermal tolerance limits, heat stress, and mortality may occur (Henshaw & Folk Jr., 1966; Licht & Leitner, 1967) if behavioral intervention is not feasible or effective (e.g., Welbergen, Klose, Markus, & Eby, 2008).…”