Global Evolutionary Patterns and Genetic Connectivity of Chemosynthetic Shrimp

To date, more than 26 shrimp species and 7 genera endemic to deep-sea chemosynthetic habitats have been described worldwide. These caridean shrimp of the family Alvinocarididae represent one of the few endemic chemosynthetic taxonomic groups distributed at almost every vent site and seep in the world, including those on back-arcs, volcanic seamounts, mid-ocean ridges, hydrocarbon seeps, and spreading centers within fracture zones. As such, they are critical ecological components in almost every recognized biogeographic province (exceptions including known sites in the Southern Ocean/East Scotia Rise, NE Pacific, and Lost City vent fields). To investigate the evolutionary and biogeographic patterns across diverse settings and biogeographic regions, we examined the phylogenetic relationships of mitochondrial genes from 22 described shrimp species and at least 3 undescribed species. We assessed the roles of depth, historical plate movements, evolutionary usage of habitat types (e.g., mid-ocean ridge vents vs. seeps), physiological adaptations, and the timing of global chemosynthetic shrimp radiation. These data indicate that habitat depth and type as well as the timing of radiation have played a significant role in the evolutionary history of alvinocard shrimp. Correlative biogeographic and evolutionary patterns are readily apparent, yet markedly inconsistent with the observed evolutionary patterns (e.g., Pacific and Atlantic Alvinocaris are not monophyletic).

We also investigated the intraspecific patterns of genetic differentiation and connectivity in populations of Opaepele loihi, Rimicaris exoculata, and Mirocaris fortunata. Mitochondrial sequences revealed strong gene flow among populations of Opaepele loihi inhabiting (eruptive) hydrothermally-active seamounts and back arc basins in the western Pacific, north of the equator, but little to no connection to those in the southern hemisphere. We suggest that venting habitats with temporally low pH and no detectable hydrogen sulfide may prohibit successful gene flow for marked periods of time. Recent technical advances allow the implementation of next-generation sequencing technologies for the rapid detection and genotyping of genome-wide Single Nucleotide Polymorphisms (SNPs) in non-model organisms, not only providing rich information for species identifications and taxonomy, but also the promise of providing insights into the population genomics, phylogeography, and evolution of deep-sea species. We employed Restriction-site-Associated DNA sequencing (RAD-seq) to quantify SNPs in individuals from Rimicaris exoculata populations, comparing Northern Mid-Atlantic ridge populations with those of the southern Mid-Atlantic ridge, and from Mirocaris fortunata populations, comparing Northern Mid-Atlantic ridge populations with those on the Southwest Indian Ridge. Utilizing thousands of SNP markers, we found different patterns of population connectivity, including small, yet significant differentiation amongst R. exoculata populations across the examined range, and more pronounced and significant genetic structure between the MAR and SW Indian Ridge among M. fortunata populations. Results support the role of the Romanche Fracture Zone as a significant barrier to dispersal and long-term connectivity in this species, but not in R. exoculata.

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First Name: 
Timothy
Last Name: 
Shank
Telephone: 
508-289-3392
Affiliation: 
Biology Department, Woods Hole Oceanographic Institution
First Name: 
Santiago
Last Name: 
Herrera
Affiliation: 
Biology Department, Woods Hole Oceanographic Institution
First Name: 
Walter
Last Name: 
Cho
Affiliation: 
Point Loma Nazarene University
Choose keywords that are most applicable to your abstract. (Three maximum.): 
Biogeography
Distribution and abundance
Evolutionary history (fossil and molecular data)
Abstract ID: 
CBE5-196