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1. Clonality contributes to the spread of Avrainvillea lacerata (Bryopsidales, Chlorophyta) in Hawai‘i

   https://doi.org/10.1111/jpy.13508  

   Thornton, Brinkley M; Spalding, Heather L; Stoeckel, Solenn; Harris, Melissa L; Wade, Rachael M; Krueger‐Hadfield, Stacy A (December 2024, Journal of Phycology)

   Abstract The relative rates of sexual versus asexual reproduction influence the partitioning of genetic diversity within and among populations. During range expansions, asexual reproduction often facilitates colonization and establishment. The arrival of the green algaAvrainvillea laceratahas caused shifts in habitat structure and community assemblages since its discovery in 1981 offshore of Oʻahu, Hawai‘i. Field observations suggest this species is spreading via vegetative reproduction. To characterize the reproductive system ofA. laceratain Hawai‘i, we developed seven microsatellite loci and genotyped 321 blades collected between 2018 and 2023 from three intertidal sites at Maunalua Bay and ʻEwa Beach. We observed one to four alleles at multiple loci, suggestingA. laceratais tetraploid. Each site was characterized by high genotypic richness (R > 0.8). However, clonal rates were also high, suggesting the vegetative spread ofA. lacerataplays a significant role. The importance of clonal reproduction for the persistence ofA. laceratain Hawai‘i is consistent with the ecological data collected for this species and observations of other abundant macroalgal invaders in Hawai‘i and other regions of the world. These data demonstrate the necessity for implementing appropriate population genetic methods and provide insights into the biology of this alga that will contribute to future studies on effective management strategies incorporating its reproductive system. This study represents one of the few that investigate green algal population genetic patterns and contributes to our understanding of algal reproductive system evolution. 

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2. Genetic and phenotypic variation exhibit both predictable and stochastic patterns across an intertidal fish metapopulation

   https://doi.org/10.1111/mec.15829  

   Thia, Joshua A.; McGuigan, Katrina; Liggins, Libby; Figueira, Will F.; Bird, Christopher E.; Mather, Andrew; Evans, Jennifer L.; Riginos, Cynthia (January 2021, Molecular Ecology)

   null (Ed.)

   Interactions among selection, gene flow, and drift affect the trajectory of adaptive evolution. In natural populations, the direction and magnitude of these processes can be variable across different spatial, temporal, or ontogenetic scales. Consequently, variability in evolutionary processes affects the predictability or stochasticity of microevolutionary outcomes. We studied an intertidal fish, Bathygobius cocosensis (Bleeker, 1854), to understand how space, time, and life stage structure genetic and phenotypic variation in a species with potentially extensive dispersal and a complex life cycle (larval dispersal preceding benthic recruitment). We sampled juvenile and adult life stages, at three sites, over three years. Genome-wide SNPs uncovered a pattern of chaotic genetic patchiness, that is, weak-but-significant patchy spatial genetic structure that was variable through time and between life stages. Outlier locus analyses suggested that targets of spatially divergent selection were mostly temporally variable, though a significant number of spatial outlier loci were shared between life stages. Head shape, a putatively ecologically responsive (adaptive) phenotype in B. cocosensis also exhibited high temporal variability within sites. However, consistent spatial relationships between sites indicated that environmental similarities among sites may generate predictable phenotype distributions across space. Our study highlights the complex microevolutionary dynamics of marine systems, where consideration of multiple ecological dimensions can reveal both predictable and stochastic patterns in the distributions of genetic and phenotypic variation. Such considerations probably apply to species that possess short, complex life cycles, have large dispersal potential and fecundities, and that inhabit heterogeneous environments. 

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3. Population genetics of the freshwater red alga Batrachospermum gelatinosum (Rhodophyta) I: Frequent intragametophytic selfing in a monoicous, haploid–diploid species

   https://doi.org/10.1111/jpy.13510  

   Shainker‐Connelly, Sarah J; Crowell, Roseanna M; Stoeckel, Solenn; Vis, Morgan L; Krueger‐Hadfield, Stacy A (December 2024, Journal of Phycology)

   Abstract Life cycles with a prolonged haploid phase are thought to be correlated with greater rates of selfing and asexual reproduction. In red algae, recent population genetic studies have aimed to test this prediction but have mostly focused on marine species with separate sexes. We characterized the reproductive system of the obligately monoicous (i.e., hermaphroditic) freshwater red algaBatrachospermum gelatinosumand predicted that we would find genetic signatures of uniparental reproduction because of its haploid‐diploid life cycle. We sampled 18 sites and genotyped 311 gametophytes with 10 polymorphic microsatellite loci to describe the reproductive system. Genotypic richness was low (<0.5) and pareto β values (describing clonal membership) were <0.7 for most sites. In taxa with separate sexes, these patterns are typically indicative of asexual reproduction. However, the genetic consequences of selfing in monoicous gametophytes are indistinguishable from those caused by asexual processes. Since we sampled gametophytes and have not yet genotyped the chantransia (i.e., the diploid phase), we interpreted low diversity as a signature of intragametophytic selfing. Additionally, to understand the factors that drive selfing, we tested latitude and several other environmental variables, but none was significantly correlated with the genetic variation we observed. Nevertheless, future studies should genotype the chantransia to measure observed heterozygosity among other summary statistics to disentangle the effects of selfing versus asexual reproduction. Together, these data, coupled with further characterization of abiotic factors that influence population genetic patterns, will allow us to test potential drivers of reproductive system evolution. 

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4. Microbiota assembly in Zostera marina during early host development across controlled growth experiments

   https://doi.org/10.1128/msystems.00722-26  

   Chaput, Gina; Deen, Emma A; Pham, Eric Q; Crystal, Sarah; Matayoshi, Andrew; Andeer, Peter; Northen, Trent R; Eisen, Jonathan A; Stachowicz, John J; Sogin, E Maggie (July 2026, mSystems)

   Bittleston, Leonora S (Ed.)

   ABSTRACT Seagrass restoration practices are evolving to leverage microbiome applications, similar to agricultural systems that have demonstrated how targeted microbial communities enhance crop resilience in challenging environments. While adult seagrass microbiome research has expanded significantly, research on the seed microbiome remains critically understudied. This gap is important given that seeds represent a large portion of restoration efforts. Advancing seed microbiome research requires standardized experimental systems for controlled plant–microbe interaction studies, which are currently lacking in seagrass research. Here, we tested fabricated ecosystem devices (EcoFAB 2.0) as a standardized system for growingZostera marina(eelgrass) seedlings, enabling a controlled study of aquatic plant–microbe interactions. Using these chambers, we addressed three key questions: (i) can we reliably grow eelgrass in a controlled laboratory setting, (ii) can we manipulate eelgrass microbiota assembly and its long-term trajectory, and (iii) can we detect shifts in the microbiota during plant development (host filtering)? Host morphology measurements and 16S rRNA gene amplicon sequencing were used to track microbiota assembly across three early developmental stages of the host. Because plants were grown in a sterile environment, surface sterilization of seeds (bleach and ethanol) removed epiphytes without disturbing the shared endophytic community, yet microbiota composition remained divergent at Stage 6 (143 differentially abundant ASVs), indicating that seed coat epiphytes make a lasting and distinct contribution to assembly trajectory. We also identified 26 stage-specific indicator ASVs across eelgrass development, suggesting stage-specific microbial associations during seedling establishment. This work demonstrates the potential for targeted manipulation of the microbiome in seagrass for restoration efforts.IMPORTANCEUsing the Fabricated Ecosystem 2.0 (EcoFAB 2.0), we were able to successfully control the microbial environment of eelgrass,Zostera marina, resulting in the reduction of epiphytes and maintaining low microbial diversity across plants without compromising the morphology and growth of seedlings. Our findings advance the marine plant model system,Z. marina, by identifying taxonomic indicators across life stages. This work lays the foundation for a targeted understanding and application of microbiomes for seagrass restoration, bridging the critical knowledge gap between agricultural seed microbiome success and marine restoration applications. 

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5. Genetic and molecular landscapes of the generalist phytopathogen Botrytis cinerea

   https://doi.org/10.1111/mpp.13404  

   Singh, Ritu; Caseys, Celine; Kliebenstein, Daniel J (January 2024, Molecular Plant Pathology)

   Abstract Botrytis cinereaPers. Fr. (teleomorph:Botryotinia fuckeliana) is a necrotrophic fungal pathogen that attacks a wide range of plants. This updated pathogen profile explores the extensive genetic diversity ofB. cinerea, highlights the progress in genome sequencing, and provides current knowledge of genetic and molecular mechanisms employed by the fungus to attack its hosts. In addition, we also discuss recent innovative strategies to combatB. cinerea. TaxonomyKingdom: Fungi, phylum: Ascomycota, subphylum: Pezizomycotina, class: Leotiomycetes, order: Helotiales, family: Sclerotiniaceae, genus:Botrytis, species:cinerea. Host rangeB. cinereainfects almost all of the plant groups (angiosperms, gymnosperms, pteridophytes, and bryophytes). To date, 1606 plant species have been identified as hosts ofB. cinerea. Genetic diversityThis polyphagous necrotroph has extensive genetic diversity at all population levels shaped by climate, geography, and plant host variation. PathogenicityGenetic architecture of virulence and host specificity is polygenic using multiple weapons to target hosts, including secretory proteins, complex signal transduction pathways, metabolites, and mobile small RNA. Disease control strategiesEfforts to controlB. cinerea, being a high‐diversity generalist pathogen, are complicated. However, integrated disease management strategies that combine cultural practices, chemical and biological controls, and the use of appropriate crop varieties will lessen yield losses. Recently, studies conducted worldwide have explored the potential of small RNA as an efficient and environmentally friendly approach for combating grey mould. However, additional research is necessary, especially on risk assessment and regulatory frameworks, to fully harness the potential of this technology. 

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