Symbiotic diversity in marine animals: the art of harnessing chemosynthesis

Abstract

Chemosynthetic symbioses between bacteria and marine invertebrates were discovered 30 years ago at hydrothermal vents on the Galapagos Rift. Remarkably, it took the discovery of these symbioses in the deep sea for scientists to realize that chemosynthetic symbioses occur worldwide in a wide range of habitats, including cold seeps, whale and wood falls, shallow-water coastal sediments and continental margins. The evolutionary success of these symbioses is evident from the wide range of animal groups that have established associations with chemosynthetic bacteria; at least seven animal phyla are known to host these symbionts. The diversity of the bacterial symbionts is equally high, and phylogenetic analyses have shown that these associations have evolved on multiple occasions by convergent evolution. This Review focuses on the diversity of chemosynthetic symbionts and their hosts, and examines the traits that have resulted in their evolutionary success.

In Situ Determination of Bacterial Growth in Mixing Zone of Hydrothermal Vent Field on the Hatoma Knoll, Southern Okinawa Trough

“…The clade of Epsilonproteobacteria consists of many ecotypes include symbiont with marine invertebrates (Dubilier et al 2008;Tokuda et al 2008;Tsuchida et al 2010), pathogen or normal flora of animals, and free-livings (Campbell et al 2006). In this study, the 16S rRNA gene sequences of Epsilonproteobacteria from a digestive tract of the Bathymodiolus have either possibility of a feed from mixing-zone bacterial population or a member of normal flora (Egas et al 2012;Van Horn et al 2011) .…”

Did shifting seawater sulfate concentrations drive the evolution of deep-sea methane-seep ecosystems?

“…Typically, only a few species account for the vast majority of the biomass in these habitats, and these dominant species live in symbiosis with chemoautotrophic bacteria, a strategy called chemosymbiosis [2]. Owing to their high degree of endemism, these vent and seep faunas were regarded geologically ancient 'relic faunas' [3,4], but molecular age estimates and the fossil record indicate a Cretaceous to early Cenozoic origin of the major clades [5,6].…”

Biophysical and Population Genetic Models Predict the Presence of “Phantom” Stepping Stones Connecting Mid-Atlantic Ridge Vent Ecosystems

“…These systems result from the penetration of oxygenated seawater into the oceanic crust, where water-rock interactions produce chemically altered fluids that reemerge from the seabed and lead to the precipitation of polymetallic sulfide deposits [2]. In the absence of sunlight, specialized microorganisms oxidize reduced compounds from the hydrothermal fluids to generate energy for carbon fixation [3]. These chemosynthetic microbes often live in symbioses with vent-dwelling invertebrate animals, creating oases of life in the otherwise sparsely populated deep-sea environment [1].…”