title: Comparative population genetics and evolutionary history of two commonly misidentified billfishes of management and conservation concern.
abstract: BACKGROUND
  Misidentifications between exploited species may lead to inaccuracies in population assessments, with potentially irreversible conservation ramifications if overexploitation of either species is occurring. A notable showcase is provided by the realization that the roundscale spearfish (Tetrapturus georgii), a recently validated species, has been historically misidentified as the morphologically very similar and severely overfished white marlin (Kajikia albida) (IUCN listing: Vulnerable). In effect, no information exists on the population status and evolutionary history of the enigmatic roundscale spearfish, a large, highly vagile and broadly distributed pelagic species. We provide the first population genetic evaluation of the roundscale spearfish, utilizing nuclear microsatellite and mitochondrial DNA sequence markers. Furthermore, we re-evaluated existing white marlin mitochondrial genetic data and present our findings in a comparative context to the roundscale spearfish.
  
  
  RESULTS
  Microsatellite and mitochondrial (control region) DNA markers provided mixed evidence for roundscale spearfish population differentiation between the western north and south Atlantic regions, depending on marker-statistical analysis combination used. Mitochondrial DNA analyses provided strong signals of historical population growth for both white marlin and roundscale spearfish, but higher genetic diversity and effective female population size (1.5-1.9X) for white marlin.
  
  
  CONCLUSIONS
  The equivocal indications of roundscale spearfish population structure, combined with a smaller effective female population size compared to the white marlin, already a species of concern, suggests that a species-specific and precautionary management strategy recognizing two management units is prudent for this newly validated billfish.
authors.affiliation: The Guy Harvey Research Institute, Oceanographic Center, Nova Southeastern University, 8000 N. Ocean Drive, Dania Beach, FL, 33004, USA. andrbern@nova.edu.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Bernard
authors.affiliation: The Guy Harvey Research Institute, Oceanographic Center, Nova Southeastern University, 8000 N. Ocean Drive, Dania Beach, FL, 33004, USA. mahmood@nova.edu.
authors.forename: Mahmood S
authors.initials: MS
authors.lastname: Shivji
authors.affiliation: National Marine Fisheries Service, Southeast Fisheries Science Center, 75 Virginia Beach Drive, Miami, FL, 33149, USA. eric.prince@noaa.gov.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Prince
authors.affiliation: Departamento de Pesca e Aquicultura, Universidade Federal Rural de Pernambuco, Rua Dom Manoel de Medeiros, s/n, Dois Irmãos, Recife, PE, 52171-032, Brazil. fhvhazin@terra.com.br.
authors.forename: Fabio H V
authors.initials: FH
authors.lastname: Hazin
authors.affiliation: Instituto Oceanográfico de Venezuela, Universidad de Oriente, Apartado de Correos, 204, Cumaná, 6101, Venezuela. farocha@udo.edu.ve.
authors.forename: Freddy
authors.initials: F
authors.lastname: Arocha
authors.affiliation: Laboratorio de Recursos Pelágicos, Dirección Nacional de Recursos Acuáticos, Constituyente 1497, Montevideo, CP, 11200, Uruguay. adomingo@dinara.gub.uy.
authors.forename: Andres
authors.initials: A
authors.lastname: Domingo
authors.affiliation: The Field Museum of Natural History, Pritzker Laboratory for Molecular Systematics and Evolution, 1400 South Lake Shore Drive, Chicago, IL, 60605, USA. kfeldheim@fieldmuseum.org.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Feldheim
mesh_terms: D000818:Animals; D001267:Atlantic Ocean; D001499:Bayes Theorem; D003247:Conservation of Natural Resources; D004272:DNA, Mitochondrial / Q000235:genetics; D019143:Evolution, Molecular; D005260:Female; D005399:Fishes / Q000235:genetics*; D049810:Genetic Speciation; D019901:Locus Control Region; D018895:Microsatellite Repeats; D011156:Population Density; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D004272:DNA, Mitochondrial