Life-history and thermal tolerance traits display different thermal plasticities and relationships with temperature in the marine polychaete Ophryotrocha labronica La Greca and Bacci (Dorvilleidae)

Trans-generational plasticity in physiological thermal tolerance is modulated by maternal pre-reproductive environment in the polychaeteOphryotrocha labronica

“…This interaction, however, ceases to have an effect when temperatures approach the upper sublethal and lethal limits. This trend confirms the fact that onset of spasms and lethal temperature are less plastic traits with respect to the other thermal tolerance limits measured in our study (see also Alford et al, 2012;Massamba-N'Siala et al, 2012;Terblanche et al, 2006). Accordingly, in O. labronica, the potential for physiological adjustments in response to increasing temperatures via maternal effects reduces towards the upper edge of the individual's thermal tolerance window, posing limits to the evolution of trans-generational plasticity of physiological performance.…”

“…Or, alternatively, the production of offspring with a wider thermal tolerance window when mother-offspring temperature conditions match could be the result of the simple passing of the maternal experiences through the generations (Marshall and Uller, 2007). Maternal experiences are not the only determinants of offspring responses: 18°C-and 30°C-acclimated offspring exhibit higher tolerance to cold and heat, respectively, independent of the maternal treatment, showing evidence for a beneficial effect of offspring acclimation temperature (Massamba-N'Siala et al, 2012). Hence, current (offspring) and past (maternal) environments interact to define offspring phenotype and its plasticity, influencing the individual's ability to cope with environmental changes.…”

“…Chill coma, defined as a reversible state where motionless individuals did not respond to prodding, was used as a measure of tolerance to cold. For heat tolerance, the following end points were observed: loss of control over activities, responsible for a reversible arrythmicity in locomotor activities [corresponding to the U-shaped end point described previously (Massamba-N'Siala et al, 2012)]; onset of spasms, where the individual displayed a spasmodic contraction of the entire body; and lethal temperature, which was defined as the temperature at which no recovery was observed after cooling (Massamba-N'Siala et al, 2012). These end points were used as proxies for the gradual physiological impairment, reversible or not, caused by the exposure to sub-optimal or lethal environmental temperatures.…”

“…Prior to starting any trial, we assessed the size of each individual by counting the number of chaetigers, i.e. the segments bearing bristles (Massamba-N'Siala et al, 2012). The number of offspring (males and females) actually measured per mother for each treatment combination ranged from 10 to 20 individuals.…”

Can multi-generational exposure to ocean warming and acidification lead to the adaptation of life-history and physiology in a marine metazoan?

“…The culture was transferred to the Marine Evolutionary Physiology (MEP) laboratory at the Université du Québec à Rimouski (Canada), where it was kept for eight generations under control conditions (temperature 27°C, pH 8, salinity 35, 12 h light:12 h dark), selected to maximize reproductive output (Åkesson, 1970). The polychaetes were fed ad libitum with minced spinach (Massamba N'Siala et al, 2012) and water was partially changed daily to prevent the accumulation of excreta and to remove uneaten spinach (Rodríguez-Romero et al, 2016).…”