Evidence for adaptive morphological plasticity in the Caribbean coral, Acropora cervicornis

Abstract

Genotype-by-environment interactions (GxE) indicate that variation in organismal traits cannot be explained by fixed effects of genetics or site-specific plastic responses alone. For tropical coral reefs experiencing dramatic environmental change, identifying the contributions of genotype, environment, and GxE on coral performance will be vital for both predicting persistence and developing restoration strategies. We quantified the impacts of G, E, and GxE on the morphology and survival of the endangered coral, Acropora cervicornis , through an in situ transplant experiment exposing common garden (nursery)-raised clones of ten genotypes to nine reef sites in the Florida Keys. By fate-tracking outplants over one year with colony-level 3D photogrammetry, we uncovered significant GxE on coral size, shape, and survivorship, indicating that no universal winner exists in terms of colony performance. Rather than differences in mean trait values, we found that individual-level morphological plasticity is adaptive in that the most plastic individuals also exhibited the fastest growth and highest survival. This indicates that adaptive morphological plasticity may continue to evolve, influencing the success of A. cervicornis and resulting reef communities in a changing climate. As focal reefs are active restoration sites, the knowledge that variation in phenotype is an important predictor of performance can be directly applied to restoration planning. Taken together, these results establish A. cervicornis as a system for studying the ecoevolutionary dynamics of phenotypic plasticity that also can inform genetic- and environment-based strategies for coral restoration.

Relationships between phenotypic plasticity and epigenetic variation in two Caribbean Acropora corals

“…While variation in growth, reproductive success, and stress tolerance across genotypes of A. cervicornis and A. palmata (Baums et al, 2013; Lohr & Patterson, 2017; Muller et al, 2021) demonstrate genetic constraints on coral fitness, phenotypic plasticity has also been reported in both species (Durante et al, 2019; Kuffner et al, 2017; Million et al, 2022). Indeed, A. cervicornis and A. palmata corals studied in the present work demonstrated environmentally induced plasticity, with environmental factors more strongly influencing the physiology of both species compared with the effect of coral genotype (Figure 2).…”

“…The significant interactive effects of genotype × site and genotype × season observed to influence coral physiology in A. cervicornis (Table 2 and Table S5) corroborate recent reports of genotype by environment interactions (GxE) in the phenotype of this species. Reciprocal transplant experiments across the Florida Reef Tract found that GxE affected the growth, morphology, bleaching response and survival of A. cervicornis (Drury et al, 2017; Drury & Lirman, 2021; Million et al, 2022). In the present work, GxE influenced the biomass and protein of the host, as well as both chlorophyll‐a and ‐c2 in A. cervicornis (Table S5).…”

“…However, the influence of GxE on the physiology of A. cervicornis indicates that genotype‐specific predictions of fitness may not be accurate for all environments where corals may be restored, and that environmentally induced phenotypic shifts will vary between genets. Metrics of phenotypic plasticity may therefore be more important to incorporate into conservation decisions rather than measures of physiological traits within a static environment (Million et al, 2022). Additionally, the quantitative links between variation in coral physiology and DNA methylation profiles identified in this study provide insights into the role of epigenetic mechanisms mediating phenotypic plasticity in invertebrates.…”

“…individuals of a particular genotype (Heyward & Collins, 1985)) at one site may not be indicative of the performance to be expected under different environmental conditions. Interestingly, morphological plasticity has been found to be adaptive and associated with higher growth rates and survival (Million et al, 2022). Therefore, quantitative measurements of phenotypic plasticity (e.g.…”

Exposure to global change and microplastics elicits an immune response in an endangered coral

“…These contrasting results may be due to different experimental design considerations across studies (Bove et al, 2020), especially given that the heat stress temperature employed here (~30.5 ˚C) was lower than most other warming studies. However, there is also significant genetic variation within A. cervicornis (Drury et al, 2017;Million et al, 2022), thus it is also possible that the genotypes used in this study were particularly resistant. Alternatively, these corals are already exposed to warmer seawater conditions where they were collected compared to other Caribbean reefs (Muñiz-Castillo et al, 2019;Bove et al, 2022b), suggesting the potential for acclimatization to elevated temperatures.…”