Seagrass Cymodocea nodosa across biogeographical regions and times: Differences in abundance, meadow structure and sexual reproduction

2b-RAD Genotyping of the Seagrass Cymodocea nodosa Along a Latitudinal Cline Identifies Candidate Genes for Environmental Adaptation

“…Genotypic richness ( R ) has been found to be highly variable across C. nodosa populations, even at small geographical scales ( Alberto et al, 2006 , 2008 ; Tuya et al, 2019 ). For instance, in the Canary Islands, the average R value previously calculated with available microsatellite markers was around 0.6, while it could vary from 0.3 to 0.9 for different meadows ( Alberto et al, 2006 ; Máñez-Crespo et al, 2020 ). Genotypic richness obtained here for the Gran Canaria population with 7 SSR markers was within this range (0.4), while genotypic richness assessed with the SNP-dataset was lower (0.2).…”

“…Previous studies on the genetic structure of C. nodosa along its distributional range based on SSRs, revealed a strong genetic discontinuity between Atlantic and Mediterranean regions and a certain divergence between western and eastern Mediterranean ( Alberto et al, 2008 ). Yet, a great heterogeneity was found across populations in terms of clonal and genetic diversity ( Ruggiero, 2004 ; Alberto et al, 2006 ; Alberto et al, 2008 ; Máñez-Crespo et al, 2020 ). A trend for decreasing allelic richness from the eastern Mediterranean towards the Atlantic was also advocated to explain the low ability of Atlantic populations to resist disturbances ( Tuya et al, 2021 ).…”

“…Flowering-regulating loci, integrating annual responses to light and temperature patterns through complex gene-regulatory networks, determine the timing of reproduction, which is crucial for fitness and survival of populations ( Austen et al, 2017 ), besides the plasticity of single long-lasting genotypes ( Pazzaglia et al, 2021 ). This could also contribute to differences in flowering phenology observed in this species along the depth gradient ( Buia and Mazzella, 1991 ) or across regions ( Máñez-Crespo et al, 2020 ). Yet, epigenetic modifications, such as histone modifications, seem to play an important role in the regulation of flowering-related gene networks, and potentially other phenology-related pathways, in C. nodosa .…”

“…Recent species distribution models predict the most relevant environmental variables defining its distribution to be sea surface temperature (SST) and salinity ( Chefaoui et al, 2016 ). Large inter-regional and local-scale variations in abundance and structure (i.e., morphology and biomass allocation), as well as the extant of sexual reproduction (as seed production) in C. nodosa have been described and correlated with different environmental conditions [i.e., seasonal patterns of Photosynthetically Active Radiation (PAR) and SST], and evolutionary contexts (i.e., genetic diversity) ( Máñez-Crespo et al, 2020 ). Populations inhabiting distinct biogeographical regions have also been shown to possess a differential resilience, performance and recovery capacity under local perturbations (e.g., shading) ( Tuya et al, 2019 ; Tuya et al, 2021 ).…”

A Tropical Macroalga (Halimeda incrassata) Enhances Diversity and Abundance of Epifaunal Assemblages in Mediterranean Seagrass Meadows

“…amphipods), which can be highly susceptible to predation (Reynolds et al, 2018), exhibited higher abundances in the seagrass meadow that harbored H. incrassata. Furthermore, the positive effects of the presence of this tropical alga may be especially relevant in winter, when C. nodosa exhibit its lowest shoot density (this work, Mañez-Crespo et al, 2020), as well as shoot size (Mañez-Crespo et al, 2020), and thus when habitat availability provided by the seagrass is reduced.…”