High Connectivity of Animal Populations in Deep-Sea Hydrothermal Vent Fields in the Central Indian Ridge Relevant to Its Geological Setting

Abstract

Dispersal ability plays a key role in the maintenance of species in spatially and temporally discrete niches of deep-sea hydrothermal vent environments. On the basis of population genetic analyses in the eastern Pacific vent fields, dispersal of animals in the mid-oceanic ridge systems generally appears to be constrained by geographical barriers such as trenches, transform faults, and microplates. Four hydrothermal vent fields (the Kairei and Edmond fields near the Rodriguez Triple Junction, and the Dodo and Solitaire fields in the Central Indian Ridge) have been discovered in the mid-oceanic ridge system of the Indian Ocean. In the present study, we monitored the dispersal of four representative animals, Austinograea rodriguezensis, Rimicaris kairei, Alviniconcha and the scaly-foot gastropods, among these vent fields by using indirect methods, i.e., phylogenetic and population genetic analyses. For all four investigated species, we estimated potentially high connectivity, i.e., no genetic difference among the populations present in vent fields located several thousands of kilometers apart; however, the direction of migration appeared to differ among the species, probably because of different dispersal strategies. Comparison of the intermediate-spreading Central Indian Ridge with the fast-spreading East Pacific Rise and slow-spreading Mid-Atlantic Ridge revealed the presence of relatively high connectivity in the intermediate- and slow-spreading ridge systems. We propose that geological background, such as spreading rate which determines distance among vent fields, is related to the larval dispersal and population establishment of vent-endemic animal species, and may play an important role in controlling connectivity among populations within a biogeographical province.

Vent Fauna on the Central Indian Ridge

“…Its distribution varies from location to location, although it is most abundant in the Kairei and Solitaire fields, and least abundant in the DoDo field. No significant differences were detected in genetic diversity between the Solitaire and Kairei populations (Beedessee et al 2013), which is consistent with the results of a previous study that found a 0.2 % difference in genetic diversity between Austinograea populations in the Kairei and Edmond fields (Van Dover et al 2001). Congeneric species are found in the western Pacific vent fields, whereas crabs of different genera are found in the eastern Pacific and MAR vent fields (summarized in Desbruyères et al 2006).…”

“…No genetic differentiation exists between R. kairei populations in the Kairei and Edmond fields (Van Dover et al 2001). Recently, population genetic analysis of R. kairei was undertaken using a partial mitochondrial cytochrome oxidase c subunit I (COI) sequence, of the three vent populations on the CIR; again, no genetic differences were detected (Beedessee et al 2013). The congeneric species R. exoculata and R. hybisae are found on both the MAR and the Mid-Cayman Rise (MCR) (Nye et al 2012).…”

“…However, the taxonomic description of this species is still in progress, and only provisional names are used. The population differentiation of this gastropod in the CIR was first examined using a partial sequence of the mitochondrial 16SrRNA gene with no genetic differentiation between the Kairei and Edmond fields (Van Dover et al 2001), whereas recent investigations have revealed significant genetic differentiation between the local populations in the Edmond and Solitaire fields (Beedessee et al 2013). Phymorhynchus, a globally distributed gastropod genus that inhabits the periphery of vent field, appears to be omnivorous species, as its nitrogen isotopic signature was not high compared to that of other animals without symbionts (Van Dover 2002).…”

Exploring the Ecology of Deep-Sea Hydrothermal Vents in a Metacommunity Framework

“…For example, Young et al (2008) found a general southward pattern of migration along the northeast Pacific system, and larger effective population sizes of the siboglinid tubeworm Ridgeia piscesae in the southern populations compared to those in the north. Coalescent approaches have also been implemented to measure long-term migration rates in mollusk and polychaete species along the EPR (Plouviez et al, 2009(Plouviez et al, , 2010(Plouviez et al, , 2013, crustacean and mollusk species in the Indian Ocean ridges (Thaler et al, 2011;Beedessee et al, 2013;Chen et al, 2015), alvinocaridid shrimp from the MidCayman Spreading Center (Plouviez et al, 2015) and the Mid-Atlantic Ridge (Teixeira et al, 2012(Teixeira et al, , 2013. Despite the evident advantages of coalescent approaches over traditional Fstatistics, the migration estimates obtained through many of these approaches are considered long-term because of necessary equilibrium assumptions over the last ∼4N e generations (i.e., average time to coalescence).…”

Genetic population structure of four hydrothermal vent shrimp species (Alvinocarididae) in the Okinawa Trough, Northwest Pacific

“…This study is the first to investigate population genetics of vent shrimps in the Northwest Pacific, facilitating comparison with the observed patterns on the MidAtlantic Ridge (MAR; Teixeira et al 2011Teixeira et al , 2012, Central Indian Ridge (CIR; Beedessee et al 2013), and in the southwestern Pacific (SWP; Thaler et al 2014).…”