Genomic variation among populations of threatened coral: Acropora cervicornis

Schopmeyer

Goergen

et al. 2017

Ecology and Evolution

Threatened Caribbean coral communities can benefit from high‐resolution genetic data used to inform management and conservation action. We use Genotyping by Sequencing (GBS) to investigate genetic patterns in the threatened coral, Acropora cervicornis, across the Florida Reef Tract (FRT) and the western Caribbean. Results show extensive population structure at regional scales and resolve previously unknown structure within the FRT. Different regions also exhibit up to threefold differences in genetic diversity (He), suggesting targeted management based on the goals and resources of each population is needed. Patterns of genetic diversity have a strong spatial component, and our results show Broward and the Lower Keys are among the most diverse populations in Florida. The genetic diversity of Caribbean staghorn coral is concentrated within populations and within individual reefs (AMOVA), highlighting the complex mosaic of population structure. This variance structure is similar over regional and local scales, which suggests that in situ nurseries are adequately capturing natural patterns of diversity, representing a resource that can replicate the average diversity of wild assemblages, serving to increase intraspecific diversity and potentially leading to improved biodiversity and ecosystem function. Results presented here can be translated into specific goals for the recovery of A. cervicornis, including active focus on low diversity areas, protection of high diversity and connectivity, and practical thresholds for responsible restoration.

Section: Discussionsupporting

confidence: 72%

Section: Introductionsupporting

confidence: 64%

Section: Discussionmentioning

confidence: 99%

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Genomic patterns in Acropora cervicornis show extensive population structure and variable genetic diversity

Schopmeyer

Goergen

et al. 2017

Ecology and Evolution

“…Standing variation in coral populations has been resolved in studies both within and among populations for many species (Ayre & Hughes, , ; Barshis et al, ; Baums, Boulay, Polato, & Hellberg, ; Baums, Johnson, Devlin‐Durante, & Miller, ; Baums, Miller, & Hellberg, , ; Bay & Palumbi, ; Cros, Toonen, Davies, & Karl, ; Davies, Treml, Kenkel, & Matz, ; Dixon et al, ; Drury et al, ; Drury, Schopmeyer, et al, ; Dziedzic et al, ; Hemond & Vollmer, ; Howells et al, ; Kenkel, Goodbody‐Gringley, et al, ; Rippe et al, ; Serrano et al, , ; Smith‐Keune & van Oppen, ; Vollmer & Palumbi, ). Although these differences are putatively neutral, they are indicative of the genetic mosaic that most coral reefs represent.…”

Section: The Adaptive Capacity Of Coralsmentioning

confidence: 99%

Resilience in reef‐building corals: The ecological and evolutionary importance of the host response to thermal stress

2020

Molecular Ecology

Coral reefs are under extreme threat due to a number of stressors, but temperature increases due to changing climate are the most severe. Rising ocean temperatures coupled with local extremes lead to extensive bleaching, where the coral‐algal symbiosis breaks down and corals may die, compromising the structure and function of reefs. Although the symbiotic nature of the coral colony has historically been a focus of research on coral resilience, the host itself is a foundational component in the response to thermal stress. Fixed effects in the coral host set trait baselines through evolutionary processes, acting on many loci of small effect to create mosaics of thermal tolerance across latitudes and individual coral reefs. These genomic differences can be strongly heritable, producing wide variation among clones of different genotypes or families of a specific larval cross. Phenotypic plasticity is overlaid on these baselines and a growing body of knowledge demonstrates the potential for acclimatization of reef‐building corals through a variety of mechanisms that promote resilience and stress tolerance. The long‐term persistence of coral reefs will require many of these mechanisms to adjust to warmer temperatures within a generation, bridging the gap to reproductive events that allow recombination of standing diversity and adaptive change. Business‐as‐usual climate scenarios will probably lead to the loss of some coral populations or species in the future, so the interaction between intragenerational effects and evolutionary pressure is critical for the survival of reefs.

“…Genetic markers also document clonality of massive morphologies, suggesting that fragmentation is common for multiple species on Caribbean reefs (Foster, Baums, & Mumby, ; Foster et al, ; Manzello et al, ; Studivan & Voss, ). However, previous work shows that genetic diversity in A. cervicornis is present and variable over small spatial scales such as individual reefs, meaning that sexual reproduction and recruitment are also important drivers of contemporary populations (Drury et al, ; Reyes & Schizas, ; Vollmer & Palumbi, ). The congeneric Acropora palmata also occurs in both monoclonal and genotypically diverse assemblages that vary between individual reefs (Baums, Devlin‐Durante, & LaJeunesse, ; Baums, Miller, & Hellberg, ).…”

Section: Introductionmentioning

confidence: 99%

Clonal diversity impacts coral cover in Acropora cervicornis thickets: Potential relationships between density, growth, and polymorphisms

Greer

Baums

et al. 2019

Ecology and Evolution

As coral reefs decline, cryptic sources of resistance and resilience to stress may be increasingly important for the persistence of these communities. Among these sources, inter‐ and intraspecific diversity remain understudied on coral reefs but extensively impact a variety of traits in other ecosystems. We use a combination of field and sequencing data at two sites in Florida and two in the Dominican Republic to examine clonal diversity and genetic differentiation of high‐ and low‐density aggregations of the threatened coral Acropora cervicornis in the Caribbean. We find that high‐density aggregations called thickets are composed of up to 30 genotypes at a single site, but 47% of genotypes are also found as isolated, discrete colonies outside these aggregations. Genet–ramet ratios are comparable for thickets (0.636) and isolated colonies after rarefaction (0.569), suggesting the composition of each aggregation is not substantially different and highlighting interactions between colonies as a potential influence on structure. There are no differences in growth rate, but a significant positive correlation between genotypic diversity and coral cover, which may be due to the influence of interactions between colonies on survivorship or fragment retention during asexual reproduction. Many polymorphisms distinguish isolated colonies from thickets despite the shared genotypes found here, including putative nonsynonymous mutations that change amino acid sequence in 25 loci. These results highlight intraspecific diversity as a density‐dependent factor that may impact traits important for the structure and function of coral reefs.