The many faced symbiotic snakelocks anemone (Anemonia viridis, Anthozoa): host and symbiont genetic differentiation among colour morphs

Abstract

How can we explain morphological variations in a holobiont? The genetic determinism of phenotypes is not always obvious and could be circumstantial in complex organisms. In symbiotic cnidarians, it is known that morphology or colour can misrepresent a complex genetic and symbiotic diversity. Anemonia viridis is a symbiotic sea anemone from temperate seas. This species displays different colour morphs based on pigment content and lives in a wide geographical range. Here, we investigated whether colour morph differentiation correlated with host genetic diversity or associated symbiotic genetic diversity by using RAD sequencing and symbiotic dinoଏagellate typing of 140 sea anemones from the English Channel and the Mediterranean Sea. We did not observe genetic differentiation among colour morphs of A. viridis at the animal host or symbiont level, rejecting the hypothesis that A. viridis colour morphs correspond to species level differences. Interestingly, we however identiଏed at least four independent animal host genetic lineages in A. viridis that differed in their associated symbiont populations. In conclusion, although the functional role of the different morphotypes of A. viridis remains to be determined, our approach provides new insights on the existence of cryptic species within A. viridis.

Horizontal acquisition of Symbiodiniaceae in the Anemonia viridis (Cnidaria, Anthozoa) species complex

“…In addition, we now describe an ubiquitous presence of the Med2 (K2) lineage at all sites, suggesting a strong ability for this lineage to occupy different habitats and maybe great dispersal capacities as well. In all lineages and sites, we detected an important clonal richness, which confirmed that A. viridis can deploy genets with a great number of ramets (Mallien et al, 2017;Porro et al, 2019;Sauer, 1986;Sauer et al, 1986;Wiedenmann et al, 2000), even if, within this sampling, the Med4 K4 (Hoffmann, 1986). More surprisingly, the ramets of the Med1 (K1), Med2 (K2) or Med3 (K3) genets were not always located at the same site and some genets were comprised of individuals present in distant sites (Tables 4 and S1), suggesting again a potentially high capacity of migration/dispersion in this species, as already F I G U R E 5 Intralocation differentiation and interlocation differentiation in symbiont microsatellite contents for the different host genetic structures (N148 data set).…”

“…After taking clonality into account, we could group the sampled individuals into 4 genetic clusters, recognized by BFD* as four differentiated lineages. As a subset of samples used in this study had already been analysed in Porro et al(2019), we could recognize that the K1 and K2 lineages from this study corresponded, respectively, to the Med1 and Med2 lineages fromPorro et al (2019). Moreover, having increased the Mediterranean sampling density, we were now able to redefine the distribution of Med1 and Med2, which are no longer single-location lineages, and identify two new lineages, named Med3 and Med4, that corresponded to the clusters K3 and K4, respectively(Figure 1 and…”

“…The analysis of ITS2 sequence variant assemblages is an effective method for comparing Symbiodiniaceae populations despite the marker's multicopy nature, which complicates data interpretation (see Hume et al, 2019). The ITS2 sequences were processed and identified using the SymPortal pipeline (Hume, 2019;Hume et al, 2019) based on a minimum entropy decomposition algorithm, as in Porro et al (2019).…”

“…Using ITS2 variability, we previously investigated the genetic diversity of the symbionts hosted by Anemonia viridis, a species of symbiotic sea anemone widely distributed in Europe, from the Mediterranean Sea to the North Sea and the west coast of Ireland, in which different cryptic species (independent lineages) have been recently identified (Porro et al, 2019). In A. viridis, a unique Symbiodiniaceae clade, 'Temperate A' (LaJeunesse et al, 2018;or A' sensu Savage et al, 2002;and Visram et al, 2006), has been identified, showing a clear genetic diversity within the clade (Casado-Amezúa et al, 2014;Porro et al, 2019). This symbiont diversity was observed with respect to the geographical origin and the host lineage (Porro et al, 2019).…”

“…In A. viridis, a unique Symbiodiniaceae clade, 'Temperate A' (LaJeunesse et al, 2018;or A' sensu Savage et al, 2002;and Visram et al, 2006), has been identified, showing a clear genetic diversity within the clade (Casado-Amezúa et al, 2014;Porro et al, 2019). This symbiont diversity was observed with respect to the geographical origin and the host lineage (Porro et al, 2019). Specifically, in this latter study, we revealed the occurrence of different assemblages of Temperate A Symbiodiniaceae in at least two lineages of A. viridis (English Channel and Mediterranean Sea).…”