Abstract:

As marine species adapt to climate change, their heat tolerance will likely be under strong selection. Individual variation in heat tolerance and its heritability underpin the potential for coral adaptation. Yet trade-offs between heat tolerance and other life history traits could compromise natural adaptation or restorative assisted evolution. Over a series of experiments in Palau, we exposed colonies of the reef-building coral Acropora digitifera to emulated long-term marine heatwave conditions. We observed remarkable within-population variability in heat tolerance, despite ubiquitous Cladocopium-dominated symbiont communities. Using climate projections, we show that for the highest level of heat tolerance, the onset of annual bleaching and mortality conditions can be delayed by up to 17 years, compared to the lowest level of heat tolerance. We found no trade-offs between heat tolerance and fecundity or 3D colony growth. More than this, an unanticipated positive association emerged with growth, such that faster-growing colonies bleached and died at higher levels of heat stress. Collectively, our intrapopulation results indicate climate adaptation potential and suggest trade-offs between heat tolerance and growth or fecundity may not be major barriers to adaptation.

Bio:

Liam Lachs of the CORALASSIST lab in Newcastle University, UK, is a final year doctoral candidate working on “Scaling-up restorative assisted evolution on Anthropocene coral reefs”. His work focusses on understanding coral heat tolerance and mass coral bleaching, working closely with the Palau International Coral Reef Centre. His research combines field and lab experiments, survey data, and climatic data with spatiotemporal Bayesian statistics and eco-evolutionary models to describe complex biological processes which play out over different spatial scales. His project is supervised by Dr. James Guest and Prof. Peter Mumby, with collaborators at various leading institutions in coral reef and climate science. In parallel with his PhD, he has been an Ambassador for the European Marine Board, sitting at the interface between science and policy, communicating to non-academic audiences about the the need to care for our oceans.