Investigation of population structure in Gulf of MexicoSeepiophila jonesi(Polychaeta, Siboglinidae) using cross-amplified microsatellite loci
Authors: Huang Chunya , Schaeffer Stephen W. , Fisher Charles R. , Cowart Dominique A. 
Published: August 2016

Background

Vestimentiferan tubeworms are some of the most recognizable fauna found at deep-sea cold seeps, isolated environments where hydrocarbon rich fluids fuel biological communities. Several studies have investigated tubeworm population structure; however, much is still unknown about larval dispersal patterns at Gulf of Mexico (GoM) seeps. As such, researchers have applied microsatellite markers as a measure for documenting the transport of vestimentiferan individuals. In the present study, we investigate the utility of microsatellites to be cross-amplified within the escarpiid clade of seep vestimentiferans, by determining if loci originally developed forEscarpiaspp. could be amplified in the GoM seep tubeworm,Seepiophila jonesi. Additionally, we determine if cross-amplified loci can reliably uncover the same signatures of high gene flow seen in a previous investigation ofS. jonesi.

Methods

Seventy-sevenS. jonesiindividuals were collected from eight seep sites across the upper Louisiana slope (<1,000 m) in the GoM. Forty-eight microsatellite loci that were originally developed forEscarpia laminata(18 loci) andEscarpia southwardae(30 loci) were tested to determine if they were homologous and polymorphic inS. jonesi. Loci found to be both polymorphic and of high quality were used to test for significant population structuring inS. jonesi.

Results

Microsatellite pre-screening identified 13 (27%) of theEscarpialoci were homologous and polymorphic inS. jonesi, revealing that microsatellites can be amplified within the escarpiid clade of vestimentiferans. Our findings uncovered low levels of heterozygosity and a lack of genetic differentiation amongstS. jonesifrom various sites and regions, in line with previous investigations that employed species-specific polymorphic loci onS. jonesiindividuals retrieved from both the same and different seep sites. The lack of genetic structure identified from these populations supports the presence of significant gene flow via larval dispersal in mixed oceanic currents.

Discussion

The ability to develop “universal” microsatellites reduces the costs associated with these analyses and allows researchers to track and investigate a wider array of taxa, which is particularly useful for organisms living at inaccessible locations such as the deep sea. Our study highlights that non-species specific microsatellites can be amplified across large evolutionary distances and still yield similar findings as species-specific loci. Further, these results show thatS. jonesicollected from various localities in the GoM represents a single panmictic population, suggesting that dispersal of lecithotrophic larvae by deep sea currents is sufficient to homogenize populations. These data are consistent with the high levels of gene flow seen inEscarpiaspp., which advocates that differences in microhabitats of seep localities lead to variation in biogeography of separate species.