title: Blue whale population structure along the eastern South Pacific Ocean: evidence of more than one population.
abstract: Blue whales (Balaenoptera musculus) were among the most intensively exploited species of whales in the world. As a consequence of this intense exploitation, blue whale sightings off the coast of Chile were uncommon by the end of the 20th century. In 2004, a feeding and nursing ground was reported in southern Chile (SCh). With the aim to investigate the genetic identity and relationship of these Chilean blue whales to those in other Southern Hemisphere areas, 60 biopsy samples were collected from blue whales in SCh between 2003 and 2009. These samples were genotyped at seven microsatellite loci and the mitochondrial control region was sequenced, allowing us to identify 52 individuals. To investigate the genetic identity of this suspected remnant population, we compared these 52 individuals to blue whales from Antarctica (ANT, n = 96), Northern Chile (NCh, n = 19) and the eastern tropical Pacific (ETP, n = 31). No significant differentiation in haplotype frequencies (mtDNA) or among genotypes (nDNA) was found between SCh, NCh and ETP, while significant differences were found between those three areas and Antarctica for both the mitochondrial and microsatellite analyses. Our results suggest at least two breeding population units or subspecies exist, which is also supported by other lines of evidence such as morphometrics and acoustics. The lack of differences detected between SCh/NCh/ETP areas supports the hypothesis that eastern South Pacific blue whales are using the ETP area as a possible breeding area. Considering the small population sizes previously reported for the SCh area, additional conservation measures and monitoring of this population should be developed and prioritized.
authors.affiliation: Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Casilla 567, Valdivia, Chile; Centro Ballena Azul/Blue Whale Center, Pamplona 58, Silos de Torobayo, Valdivia, Chile.
authors.forename: J P
authors.initials: JP
authors.lastname: Torres-Florez
authors.forename: R
authors.initials: R
authors.lastname: Hucke-Gaete
authors.forename: R
authors.initials: R
authors.lastname: LeDuc
authors.forename: A
authors.initials: A
authors.lastname: Lang
authors.forename: B
authors.initials: B
authors.lastname: Taylor
authors.forename: L E
authors.initials: LE
authors.lastname: Pimper
authors.forename: L
authors.initials: L
authors.lastname: Bedriñana-Romano
authors.forename: H C
authors.initials: HC
authors.lastname: Rosenbaum
authors.forename: C C
authors.initials: CC
authors.lastname: Figueroa
mesh_terms: D025041:Animal Migration; D000818:Animals; D000864:Antarctic Regions; D050616:Balaenoptera / Q000235:genetics*; D001499:Bayes Theorem; D002467:Cell Nucleus / Q000235:genetics; D002677:Chile; D016000:Cluster Analysis; D004272:DNA, Mitochondrial / Q000235:genetics; D005260:Female; D051456:Gene Flow; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D006239:Haplotypes; D008297:Male; D018895:Microsatellite Repeats; D010140:Pacific Ocean; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial
keywords: Balaenoptera musculus; biodiversity conservation; conservation genetics; eastern South Pacific; endangered species