Biology subjects

Claar, D. C.

Publications and source records attributed to Claar, D. C..

2 recordsLinked to original sources

bioRxiv2023

Marine heatwaves threaten cryptic coral diversity and erode associations amongst coevolving partners

Climate change-amplified heatwaves are known to drive extensive mortality in marine foundation species. However, a paucity of longitudinal genomic datasets has impeded understanding of how these rapid selection events alter species genetic structure. Impacts of these events may be exacerbated in species with obligate symbioses, where the genetics of multiple co-evolving species may be affected. Here, we tracked the symbiotic associations and fate of reef-building corals for six years through a prolonged heatwave. Coral genetics strongly predicted survival of the common coral Porites through the event, with strong differential survival (15 to 64%) apparent across morphologically identical -but genetically distinct- lineages. The event also disrupted strong associations between coral lineages and their symbiotic partners, homogenizing symbiotic assemblages across lineages and reducing the specificity of coral-algal symbioses. These results highlight that marine heatwaves threaten cryptic genetic diversity of foundation species and have the potential to decouple tight relationships between co-evolving host-symbiont pairs.

ecology↗

bioRxiv2022

Transformation of coral communities subjected to an unprecedented heatwave is modulated by local disturbance

Corals are imminently threatened by climate change-amplified marine heatwaves. Yet how to conserve reef ecosystems faced with this threat remains unclear, since protected reefs often seem equally or more susceptible to thermal stress as unprotected ones. Here, we disentangle this apparent paradox, revealing that the relationship between reef disturbance and heatwave impacts depends upon the focal scale of biological organization. We document a heatwave of unprecedented duration that culminated in an 89% loss of coral cover. At the community level, losses hinged on pre-heatwave community structure, with sites dominated by competitive corals--which were predominantly protected from local disturbance--undergoing the greatest losses. In contrast, at the species level, survivorship of individual coral colonies typically decreased as local disturbance intensified, illustrating that underlying chronic disturbances can impair resilience to thermal stress at this scale. Our study advances understanding of the relationship between climate change and local disturbance, knowledge of which is crucial for coral conservation this century.

ecology↗