Population Structure of the Cold Seep Tubeworm Seepiophila jonesi (polychaeta, Siboglinidae)in the Gulf Of Mexico

Open Access
Author:
Huang, Chunya
Area of Honors:
Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Stephen Wade Schaeffer, Thesis Supervisor
  • Stephen Wade Schaeffer, Honors Advisor
  • Dr James Marden, Faculty Reader
Keywords:
  • vestimentiferan
  • tubeworms
  • Gulf of Mexico
  • population genetics
  • population structure
  • Seepiophila jonesi
  • microsatellites
Abstract:
Vestimentiferan tubeworms are a group of marine sessile polychaete annelids (family: Sibolinidae) found at hydrothermal vents and cold hydrocarbon seeps where reduced hydrogen sulfide is abundant. They depend on their internal sulfide-oxidizing symbionts for fixed hydrocarbons. The hydrocarbon seeps on the Louisiana Slope of the Gulf of Mexico support many deep-sea communities formed by tubeworm aggregations. Those aggregations, in turn, provide ultimate protection and form suitable habitats for a variety of marine organisms. Also, as tubeworms face several anthropogenic threats that damage populations, such as the oils spill and oil drilling, it is crucial to understand the potential for these species to re-colonize populations to prevent extinction. This study tested the hypothesis that S. jonesi populations are not structured. This study implemented 13 microsatellite loci that successfully cross-amplified from Escarpia laminata (five loci) and Escarpia southwardae (eight loci) to test for population substructure in 77 S. jonesi individuals collected from eight seep sites across the Gulf of Mexico. The microsatellite loci were tested for the presence of null alleles, which can artificial lower estimates of heterozygosity. We also tested pairs of loci for significant linkage disequilibrium, which can indicate loci are linked and have correlated histories. Allelic and private allelic richness, heterozygosity, linkage disequilibrium, and Wright’s F-statistics were utilized to analyze data and assess genetic diversity and population structure. Just as hypothesized, S. jonesi failed to show evidence of significant population structure. The results suggest that there was a significant gene flow through larval dispersal in the mixed oceanic currents and that S. jonesi are capable of reducing anthropogenic threats to them by settling at new locations. Private alleles were commonly located on the extremes of the allele size distribution due to the evolution of microsatellites and mutations.