Fine-scale spatial genetic structure in a temperate octocoral: insights into the eco-evolutionary processes underlying the population dynamics in the threatened Mediterranean red coral

1st Iberian Ecological Society Meeting (2019); XIV Congreso Nacional de la Asociación Española de Ecología Terrestre (AEET), Ecology: an integrative science in the Anthropocene, 4-7 February 2019, Barcelona, Spain
Characterizing the eco-evolutionary processes underlying population dynamics is a crucial task for evolutionary ecologists because of its conservation implications. The study of fine-scale spatial genetic structure (SGS), the nonrandom spatial distribution of genotypes within a population, is particularly relevant in this context because it allows inferring the interaction among demographic and evolutionary processes acting within populations. Corallium rubrum, is a habitat-forming precious octocoral from the coralligenous, one of the most diverse but also most threatened Mediterranean habitats. This long-lived species, showing low population dynamics and restricted dispersal capacity, is affected by overfishing (for its use in jewelry) and warming-induced mortality events. While these two pressures lead to dramatic shifts in population demographic structure, little is known regarding their impact on red coral population dynamics. Here, we combined population genetics (14 microsatellites), demographic surveys and photogrammetric methods to further our understanding of red coral population dynamics and to test how it may be impacted by population decline. First, focusing on a pristine-like population, we showed a decrease of SGS from recruits to adults as expected when recruits thin. Then, we compared the patterns of SGS in three populations with contrasted conservation status to characterize the interaction among demographic structure and eco-evolutionary processes (effective dispersal and genetic drift). We showed that demographic erosion induced a simplification of the network of relationships among colonies impacting the underlying processes. This study sheds new light on the dynamics of the red coral with implications for the restoration of similar species