Estimating the potential for coral adaptation to global warming across the Indo‐West Pacific

Abstract

The potential of reef-building corals to adapt to increasing sea-surface temperatures is often debated but has rarely been comprehensively modeled on a region-wide scale. We used individual-based simulations to model adaptation to warming in a coral metapopulation comprising 680 reefs and representing the whole of the Central Indo-West Pacific. Encouragingly, some reefs-most notably Vietnam, Japan, Taiwan, New Caledonia and the southern half of the Great Barrier Reef-exhibited high capacity for adaptation and, in our model, maintained coral cover even under a rapid "business-as-usual" warming scenario throughout the modeled period (200 years). Higher resilience of these reefs was observed under all tested parameter settings except the models prohibiting selection and/or migration during warming. At the same time, the majority of reefs in the region tended to collapse within the first 100 years of warming. The adaptive potential (odds of maintaining high coral cover) of a given reef could be predicted based on two metrics: the reef's present-day temperature, and the proportion of recruits immigrating from warmer locations. The latter metric explains the most variation in adaptive potential, and significantly correlates with actual coral cover changes observed throughout the region between the 1970s and the early 2000s. These findings will help prioritize coral conservation efforts and plan assisted gene flow interventions to boost the adaptive potential of specific coral populations. K E Y W O R D S adaptation, assisted gene flow, climate change, individual-based modeling, metapopulation S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section.

Host genotype and stable differences in algal symbiont communities explain patterns of thermal stress response ofMontipora capitatafollowing thermal pre-exposure and across multiple bleaching events

“…Adaptation results in gradual adjustment to changing environmental conditions at the population level (van Oppen et al 2015), but corals will likely only be able to successfully adapt to a changing climate if current greenhouse gas emissions are significantly reduced (Császár et al 2010). The adaptation rate of scleractinian corals is likely too slow to keep pace with the rapid environmental changes expected under future climate change (Bay et al 2017;Matz et al 2018), and the adaptive capacity of many coral reefs based on standing diversity is expected to be overwhelmed within a century (Matz et al 2020). Acclimatization occurs through non-genetic changes at the individual rather than population level and can take place more rapidly, within a single generation (van Oppen et al 2015).…”

Coral conservation requires ecological climate‐change vulnerability assessments

“…Thermal adaptation has been linked to various SST characteristics, such as heating rate (Middlebrook et al 2010), diurnal variability (Safaie et al 2018), and high historical chronic and acute thermal stress (Mumby et al 2011). However, these studies do not account for variability in adaptive capacity between species subjected to the same thermal disturbance (Safaie et al 2018) or external factors affecting a site's adaptive capacity (eg supply of coral recruits adapted to warmer environments; Matz et al 2020). Because adaptation is not guaranteed in locations that have been affected by past bleaching events (Hughes et al 2017b), thermal regimes alone cannot provide a proxy for adaptive capacity in the identification of low vulnerability areas.…”

Evolution and connectivity influence the persistence and recovery of coral reefs under climate change in the Caribbean, Southwest Pacific, and Coral Triangle

“…Subpopulations experience selection to adapt to their local environment, yet can also receive immigrants adapted to different environments. While there is increasing recognition for the contribution of evolution to coral persistence under future conditions (Logan et al, 2014; Matz et al, 2018, 2020a; Walsworth et al, 2019), there is less understanding of the interactions between evolutionary potential and reef characteristics on coral survival within regional-scale reef networks.…”

“…Due to evidence of thermal adaptation and heritability of heat tolerance in corals (Dixon et al, 2015; Dziedzic et al, 2019a; Kirk et al, 2018a), metrics that quantify the relative temperature of a patch and overall temperature change may be consequential determinants of individual reef persistence. In fact, in a recent modeling study of corals in the Indo-West Pacific, both the proportion of recruits immigrating from warmer locations and the present-day temperature were found to be useful factors in determining corals’ projected adaptive response (Matz et al, 2020a). Therefore, from an evolutionary perspective, larval dispersal facilitates the exchange of traits across a network.…”

“…Climate change is impacting reefs across the world, but the rates of temperature change (McClanahan et al, 2019) and the structure of dispersal networks (Wood et al, 2014) differ substantially across regions. While most modeling work addressing coral adaptation has focused on the Indo-West Pacific region (Kleypas et al, 2016; Matz et al, 2018, 2020a), corals exist around the world, including throughout the Pacific and in the Caribbean (Veron, 1995). Comparisons among reef systems are important for understanding which results are general and which are sensitive to particular geographic contexts.…”