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Phenotypic plasticity and evolutionary adaptation allow populations to cope with global change, but limits and costs to adaptation under multiple stressors are insufficiently understood. We reared a foundational copepod species,Acartia hudsonica, under ambient (AM), ocean warming (OW), ocean acidification (OA), and combined ocean warming and acidification (OWA) conditions for 11 generations (approx. 1 year) and measured population fitness (net reproductive rate) derived from six life-history traits (egg production, hatching success, survival, development time, body size and sex ratio). Copepods under OW and OWA exhibited an initial approximately 40% fitness decline relative to AM, but fully recovered within four generations, consistent with an adaptive response and demonstrating synergy between stressors. At generation 11, however, fitness was approximately 24% lower for OWA compared with the AM lineage, consistent with the cost of producing OWA-adapted phenotypes. Fitness of the OWA lineage was not affected by reversal to AM or low food environments, indicating sustained phenotypic plasticity. These results mimic those of a congener,Acartia tonsa, while additionally suggesting that synergistic effects of simultaneous stressors exert costs that limit fitness recovery but can sustain plasticity. Thus, even when closely related species experience similar stressors, species-specific costs shape their unique adaptive responses.
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Developmental temperature, more than long‐term evolution, defines thermal tolerance in an estuarine copepod
Abstract Climate change is resulting in increasing ocean temperatures and salinity variability, particularly in estuarine environments. Tolerance of temperature and salinity change interact and thus may impact organismal resilience. Populations can respond to multiple stressors in the short‐term (i.e., plasticity) or over longer timescales (i.e., adaptation). However, little is known about the short‐ or long‐term effects of elevated temperature on the tolerance of acute temperature and salinity changes. Here, we characterized the response of the near‐shore and estuarine copepod,Acartia tonsa, to temperature and salinity stress. Copepods originated from one of two sets of replicated >40 generation‐old temperature‐adapted lines: ambient (AM, 18°C) and ocean warming (OW, 22°C). Copepods from these lines were subjected to one and three generations at the reciprocal temperature. Copepods from all treatments were then assessed for differences in acute temperature and salinity tolerance. Development (one generation), three generations, and >40 generations of warming increased thermal tolerance compared to Ambient conditions, with development in OW resulting in equal thermal tolerance to three and >40 generations of OW. Strikingly, developmental OW and >40 generations of OW had no effect on low salinity tolerance relative to ambient. By contrast, when environmental salinity was reduced first, copepods had lower thermal tolerances. These results highlight the critical role for plasticity in the copepod climate response and suggest that salinity variability may reduce copepod tolerance to subsequent warming.
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- PAR ID:
- 10491645
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 14
- Issue:
- 2
- ISSN:
- 2045-7758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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