Costs and Consequences of Adaptation to Combined Warming and Acidification for Two Estuarine Copepods
The rapid pace of climate change represents a potential threat to population persistence in marine systems. Predicting the response of marine metazoans to climate change is hampered by a lack of studies on evolutionary adaptation, particularly to combined warming and acidification (OWA). This disser...
| Other Authors: | , , , , , , |
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| Format: | Text |
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University of Connecticut
2021
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| Online Access: | http://hdl.handle.net/11134/20002:860664042 https://digitalcollections.ctstatelibrary.org/islandora/object/20002%3A860664042/datastream/TN/view/Costs%20and%20Consequences%20of%20Adaptation%20to%20Combined%20Warming%20and%20Acidification%20for%20Two%20Estuarine%20Copepods.jpg |
| Summary: | The rapid pace of climate change represents a potential threat to population persistence in marine systems. Predicting the response of marine metazoans to climate change is hampered by a lack of studies on evolutionary adaptation, particularly to combined warming and acidification (OWA). This dissertation explores the adaptive capacity to ocean warming and acidification of copepods, arguably the most abundant metazoans on the planet. Using an experimental evolution approach, I tracked fitness-relevant life-history traits for multiple generations in two copepod species with different phenologies and life histories – the summer dominant species Acartia tonsa and the winter dominant Acartia hudsonica – in response to ocean warming, ocean acidification, and their combination (OWA). Population fitness (the net reproductive rate per generation) initially decreased under OWA but recovered after two to three generations. However, antagonistic interactions between warming and acidification in later generations limited fitness recovery. Reciprocal transplant and food limitation experiments revealed trade-offs and potential costs of adaptation to OWA. The costs experienced by A. tonsa included increased susceptibility to food limitation when returned to ambient conditions and, paradoxically, lower thermal tolerance. Whereas A. hudsonica experienced sustained phenotypic plasticity, the overall fitness was lower than alternate lineages in foreign environments, suggesting a cost to this plasticity. The differences in costs experienced suggests a seasonal component to OWA adaptation. Across generations, A. tonsa adapted to OWA experience changing sex ratios which is reflected in the differential gene expression profiles. Moreover, contrasting analyses following adaptation revealed that differential gene expression is low for adapted lineages relative to control lineages for A. tonsa and A. hudsonica. These results highlight the importance of testing the adaptive capacity of species with different life-history strategies or ... |
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