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- Title
Evolved tolerance to NaCl does not alter Daphnia response to acute heat stress.
- Authors
Sun, Xinyu; Arnott, Shelley E.
- Abstract
Adaptation to one stressor can influence organismal responses to future environmental changes, either to the same or a novel stressor. But there is a lack of research on this topic, particularly in the context of freshwater habitats. Fluctuating salinity and heatwaves that are becoming more frequent and intensified are affecting freshwater ecosystems. We applied an experimental evolution approach to examine the influence of adaptation to elevated salinity on the population's responses to subsequent salt and heat stress. We conducted lab experiments using Daphnia pulicaria cultured from individuals with previous 8-week exposure history to two salinity treatments (6.5 or 350 mg Cl−/L). Iso-female lines with or without prior exposure to elevated salinity were assayed along a salt gradient (18.5 to 1500 mg Cl−/L) or an acute heat gradient treatment (20 to 35 °C). Our results showed that Daphnia survival, fecundity, and body length growth rate declined with increased salt concentration, with survival and fecundity being most sensitive. The treatment group with previous salt exposure history had higher survival and fecundity than the naïve treatment group when treated with salt, without loss of fitness under low-salinity conditions. Daphnia survival and growth rates were reduced in temperatures higher than 30 °C. Despite the fact that the two stressors can induce similar defense mechanisms, previous exposure history to salt did not prevent Daphnia populations from experiencing reduced survival and growth rates under heated conditions. Our work demonstrates that organisms can rapidly adapt to a stressor that protects them from later exposure to increases in this stressor, without a trade-off in fitness under undisturbed conditions, but this evolved tolerance cannot protect them from all levels of this stressor or alleviate damage by a novel one.
- Subjects
DAPHNIA; EFFECT of salt on plants; FRESHWATER habitats; HEAT waves (Meteorology); SALINITY; SALT
- Publication
Evolutionary Ecology, 2023, Vol 37, Issue 2, p345
- ISSN
0269-7653
- Publication type
Article
- DOI
10.1007/s10682-022-10220-6