Biology subjects

Bartels, E.

Publications and source records attributed to Bartels, E..

5 recordsLinked to original sources

bioRxiv2026

Reproductive Trade-offs in Caribbean Corals: Plasticity Accelerates While Fragmentation Delays Reproductive Capacity

In modular organisms, where growth and fragmentation blur the boundaries between individuals, the interplay between asexual and sexual reproduction creates complex fitness trade-offs. Life-history theory predicts that resources allocated to one fitness component necessarily reduce investment in others, yet detecting these trade-offs in wild populations of clonal organisms remains challenging. Phenotypic plasticity can enhance survival, yet its influence on reproductive capacity and life history trade-offs remains poorly understood. Using a fully crossed reciprocal transplant design, we tracked 263 colonies of the branching coral Acropora cervicornis across nine reef sites over 42 months, investigating relationships between fragmentation, morphological plasticity, and the capacity for sexual reproduction. Breakage patterns reflected both environmental and genetic factors. Primary branch breaks created a "double negative" effect--simultaneously more than doubling mortality risk and delaying attainment of a validated reproductive size class by [~]40%. Conversely, higher morphological plasticity in surface area-to-volume ratio accelerated sexual maturation up to 6-fold, counteracting the negative effects of fragmentation. In parallel, a simple demographic model parameterized with published fecundity data estimated that primary breakage reduces expected cumulative reproductive output by [~]58%, a result robust across a wide range of parameter assumptions. These results demonstrate a fundamental reproductive trade-off in which asexual reproduction through fragmentation undermines sexual reproductive potential by reducing colony size. Moreover, our findings reveal that fragmentation susceptibility is broadly heritable and subject to selection, and identify a compensatory mechanism through which plasticity enhances fitness beyond immediate survival.

evolutionary biology↗

bioRxiv2025

Habitat suitability modeling growth and cover trends of staghorn coral (Acropora cervicornis) outplants in the lower Florida Keys

The decline of important reef building corals has motivated the development of habitat suitability models used to identify optimal locations for coral restoration. In the Florida Keys habitat suitability models incorporate coarse spatial data sampled over large areas, resulting in recommended outplant sites at distant locations, making it logistically difficult and expensive to access and regularly monitor. Restoration efforts to date show that outplanting success can vary widely within a limited space, necessitating improved predictive abilities of coral outplant success at high spatial resolutions within a restoration site. With the advent of Structure-from-Motion image reconstruction, fine-scale, site specific, digital terrain models can be created to support habitat suitability model development. In this study, generalized linear mixed models used extracted seafloor terrain attributes and environmental variables to identify within site locations of high Acropora cervicornis growth and healthy coral cover of long-term outplants. Percent healthy coral cover significantly decreased after two years of outplantation. The submodel of corals exclusively less than two years old was unable to identify environmental conditions associated with higher healthy cover. For all corals, outplant recommendations for higher healthy cover are in deeper waters, away from the coast, in less rough terrain, and closer to the reef edge. Model results for growth support these recommended outplant sites, in addition to concave locations near high slope relief. Finally, our results also indicate that marine heat waves, but especially marine cold waves negatively correspond with coral growth, and high wind events positively correspond with coral growth. These model results provide a basis for further endeavors in modeling endangered organismal success, which are vulnerable to minute differences in local environmental conditions.

ecology↗

bioRxiv2022

Long term maintenance of heterologous symbiont association in Acropora palmata on natural reefs

The sensitivity of reef-building coral to elevated temperature is a function of their symbiosis with dinoflagellate algae in the family Symbiodiniaceae. Changes in the composition of the endosymbiont community in response to thermal stress can increase coral thermal tolerance. Consequently, this mechanism is being investigated as a human-assisted intervention for rapid acclimation of coral in the face of climate change. Successful establishment of novel symbioses that increase coral thermal tolerance have been demonstrated in laboratory conditions; however, it is unclear how long these heterologous relationships persist in nature. Here, we show that Acropora palmata can form a novel symbiosis with Durusdinium spp. when reared in land-based aquaria. We tested the stability of this heterologous relationship by outplanting clonal replicates (ramets) of five A. palmata host genotypes to natural reefs in the lower Florida Keys. Amplicon sequencing analysis of ITS2-type profiles revealed that the majority of surviving ramets remained dominated by Durusdinium spp. two years after transplantation. However, 15% of ramets, including representatives of all genotypes, did exhibit some degree of symbiont shuffling or switching at six of eight sites, including complete takeover by site-specific strains of the native symbiont, Symbiodinium fitti. The predominant long-term stability of the novel symbiosis supports the potential effectiveness of symbiont modification as a management tool. However, the finding that 6-7 year-old coral can alter symbiont community composition in the absence of bleaching indicates that Symbiodiniaceae communities are indeed capable of greater flexibility under ambient conditions.

microbiology↗

bioRxiv2022

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

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, A. 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 and survivorship indicating that no universal winner exists in terms of colony performance. Moreover, the presence of GxE also implies the existence of intraspecific variation in phenotypic plasticity. Rather than differences in mean trait values, we find 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 eco-evolutionary dynamics of phenotypic plasticity that also can inform genetic- and environment-based strategies for coral restoration.

ecology↗

bioRxiv2021

Host-specific epibiomes of distinct Acropora cervicornis genotypes persist after field transplantation

Microbiome studies across taxa have established the influence of host genotype on microbial recruitment and maintenance. However, research exploring host-specific epibionts in scleractinian corals is scant and the influence of intraspecific differences across environments remains unclear. Here, we studied the epibiome of ten Acropora cervicornis genotypes to investigate the relative roles of host genotype and environment in structuring the epibiome. Coral mucus was sampled in a common garden nursery from replicate ramets of distinct genotypes (T0). Coral fragment replicates (n=3) of each genotype were then transplanted to nine different field sites in the Lower Florida Keys and mucus was again sampled one year later from surviving ramets (T12). 16S rRNA amplicon sequencing was used to assess microbial composition, richness, and beta-diversity. The most abundant and consistent amplicon sequencing variants (ASVs) in all samples belonged to Fokiniaceae (MD3-55 genus) and Cyanobacteria (Synechococccus). The abundances of these bacterial taxa varied consistently between genotypes whereas neither the composition nor taxonomic abundance were significantly different among field sites. Interestingly, several high MD3-55 hosting genotypes showed rapid diversification and an increase in MD3-55 following transplantation. Overall, our results indicate healthy A. cervicornis genotypes retain distinct epibiome signatures through time, suggesting a strong host component. Lastly, our results show that differences in MD3-55 abundances can be consistently detected in the epibiome of distinct host-genotypes of A. cervicornis. As this organism (sensu Aquarickettsia rohweri) has been implicated as a marker of disease resistance, this finding reinforces the potential use of microbial indicators in reef restoration efforts via non-invasive surface/mucus sampling.

ecology↗