Potential for adaptation to climate change: family-level variation in fitness-related traits and their responses to heat waves in a snail population

Abstract

BackgroundOn-going global climate change poses a serious threat for natural populations unless they are able to evolutionarily adapt to changing environmental conditions (e.g. increasing average temperatures, occurrence of extreme weather events). A prerequisite for evolutionary change is within-population heritable genetic variation in traits subject to selection. In relation to climate change, mainly phenological traits as well as heat and desiccation resistance have been examined for such variation. Therefore, it is important to investigate adaptive potential under climate change conditions across a broader range of traits. This is especially true for life-history traits and defences against natural enemies (e.g. parasites) since they influence organisms’ fitness both directly and through species interactions. We examined the adaptive potential of fitness-related traits and their responses to heat waves in a population of a freshwater snail, Lymnaea stagnalis. We estimated family-level variation and covariation in life history (size, reproduction) and constitutive immune defence traits [haemocyte concentration, phenoloxidase (PO)-like activity, antibacterial activity of haemolymph] in snails experimentally exposed to typical (15 °C) and heat wave (25 °C) temperatures. We also assessed variation in the reaction norms of these traits between the treatments.ResultsWe found that at the heat wave temperature, snails were larger and reproduced more, while their immune defence was reduced. Snails showed high family-level variation in all examined traits within both temperature treatments. The only negative genetic correlation (between reproduction and antibacterial activity) appeared at the high temperature. However, we found no family-level variation in the responses of most examined traits to the experimental heat wave (i.e. largely parallel reaction norms between the treatments). Only the reduction of PO-like activity when exposed to the high temperature showed family-level variation, suggesting that the cost of heat waves may be lower for some families and could evolve under selection.ConclusionOur results suggest that there is genetic potential for adaptation within both thermal environments and that trait evolution may not be strongly affected by trade-offs between them. However, rare differences in thermal reaction norms across families indicate limited evolutionary potential in the responses of snails to changing temperatures during extreme weather events.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0988-x) contains supplementary material, which is available to authorized users.

Diurnal variation around an optimum and near‐critically high temperature does not alter the performance of an ectothermic aquatic grazer

“…Just as acclimation can increase an individual's thermal tolerance (Colinet et al, 2015;Marshall, Brahim, Mustapha, Dong, & Sinclair, 2018), natural selection should alter thermal responses in populations over contemporary evolutionary timescales (Merilä & Hendry, 2014). For instance, Leicht, Seppälä, and Seppälä (2017) observed high family-level trait variation in L. stagnalis at different temperatures suggesting some evolutionary potential in response to warming in our model organism. However, the evidence still remains weak, with numerous examples contradicting these predictions (e.g., Fragata et al, 2016;van Heerwaarden, Lee, Overgaard, & Sgrò, 2014;Manenti et al, 2017 organismal responses to environmental heterogeneity (Manenti et al, 2017).…”

Direct and transgenerational effects of an experimental heatwave on early life stages in a freshwater snail

“…heatwave) temperature as it reduces immune defence and life history traits in adult snails Seppälä & Jokela, 2011), lies above the thermal optimum for development and growth of juvenile snails (Vaughn, 1953), and occurs intermittently in habitats of snails during hot summers (T. Salo, unpublished data). We did not measure the number of oviposited eggs in this experiment as the effect of temperature on snail fecundity has been described in detail in earlier studies (Leicht et al, , 2017. Note that we assigned more individuals into the high-temperature treatment because we expected increased mortality in those snails.…”

“…Since L. stagnalis prefers outcrossing (Nakadera, Mariën, Van Straalen, & Koene, 2017;Puurtinen, Knott, Suonpää, Nissinen, & Kaitala, 2007), often engages in multiple matings (Nakadera et al, 2017), and can store sperm from those matings for over 2 months (Nakadera, Blom, & Koene, 2014), the collected individuals probably carried alleles from a higher number of snails. We maintained the stock population in the approximate size of 400 individuals at 15 ± 2°C (control temperature used in the experiment; see the section about the experimental design below) for 2 years before the study (see Leicht, Seppälä, & Seppälä, 2017). At the time of the experiment, the stock population showed genetic polymorphism typical for natural populations in northern Switzerland (Leicht, Jokela, & Seppälä, 2019).…”

“…At 25°C, 39 snails survived, and 34 of them reproduced. We did not measure the number of oviposited eggs in this experiment as the effect of temperature on snail fecundity has been described in detail in earlier studies (Leicht et al, , 2017.…”

Direct and transgenerational effects of an experimental heat wave on early life stages in a freshwater snail

“…Since L. stagnalis prefers outcrossing (Puurtinen et al 2007;Nakadera et al 2017), often engages in multiple matings (Nakadera et al 2017), and can store sperm from those matings for over two months (Nakadera, Blom & Koene 2014), the stock population can be expected to reflect the genetic variation in the source population well. We maintained the stock population in the approximate size of 400 individuals at 15 ± 2°C (control temperature used in the experiment; see the section about experimental design below) for two years before the study (see Leicht, Seppälä & Seppälä 2017).…”