Speaker
Description
Host-microbe associations are essential for the health of seagrass meadows. While the seagrasses themselves host specific and benefical ‘microbiomes’, also symbionts of co-occurring animals can benefit the seagrass ecosystem, such as the sulfur-oxidizing Thiodiazotropha endosymbionts of lucinid clams that ‘detoxify’ seagrass sediments. Molecular surveys are revealing members of the genus Thiodiazotropha in root and rhizome microbiomes of seagrasses, however, their relationships to clam symbionts are unknown. We used a combination of sequencing techniques to reveal the diversity of Thiodiazotropha symbionts in co-occurring lucinids and seagrass Cymodocea nodosa. In >100 clams, within-host symbiont diversity was greater than previously observed, with multiple symbiont types co-occurring regularly. These symbionts were also identified on seagrass roots in the surrounding environment along with many other Thiodiazotropha sequence variants. The environment may therefore have a greater influence on symbiont diversity than previously thought by offering a secondary niche. Using a metacommunity model, we show that the presence of a second co-occurring host type (seagrass) can increase symbiont diversity within clams. Intimate symbionts are usually highly specialized to associate with a particular host species. Thiodiaoztropha would be the first symbiont capable of intimate associations with both a plant and an animal host.
