Two Genetically Distinct Forms of Rougheye Rockfish Are Different Species

Abstract

The variation in mitochondrial DNA (mtDNA) and at eight microsatellite loci was analyzed in 700 rougheye rockfish Sebastes aleutianus sampled along the Pacific Rim from the Oregon coast to the western Aleutian Islands and Bering Sea. The program STRUCTURE was used to analyze the microsatellite genotypes and determine that the samples probably came from two genetically distinct sources (type I and type II) by minimizing the strong HardyϪWeinberg and gametic disequilibria observed in the total sample. The two types had nearly fixed differences at one microsatellite locus (Sma 6), which corresponded to divergent mtDNA haplotype clusters. We conclude that these two types are distinct species. The ranges of the two types overlapped but were not coincident; in some areas, one or the other predominated. For example, most of the Aleutian Island samples were type I fish. Although both types were caught in the same hauls in some regions, often one or the other species was predominant in a haul. The differences in distributions suggest a historic vicariant or ecological basis for their divergence. No phenotypic characteristics have been confirmed that can be used to distinguish the two species visually. Rougheye rockfish have high commercial value and their incidental catch has the potential to greatly affect larger fisheries. The discovery of cryptic speciation in a commercially important species underscores our need to learn more about the distribution and biology of these and other groundfish species.

Distinction of saffron cod (Eleginus gracilis) from several other gadid species by using microsatellite markers

“…In these analyses, the two collections of E. gracilis, and the collections of M. proximus, and E. nawaga were all distinct from each other (P<0.0001). The degree of their divergences mostly exceeded those observed between S. aleutianus and S. melanostictus (Gharrett et al, 2005) and each of the collections clustered separately in PCAs. It is notable that misidentified individuals of Prince William Sound M. proximus were collected at the same site with E. gracilis, but were genetically distinct from them.…”

The utility and limitations of genetic data for stock identification and management of North Pacific rockfish (Sebastes spp.)

“…This identification is critical when assessing stock structure of commercially important species, especially when abundance and productivity differs among stocks. Two studies using mtDNA sequences and microsatellite loci have suggested that rougheye rockfish populations (S. aleutianus), ranging from the Oregon coast to the Aleutian Islands, are actually composed of two genetically distinct groups and are likely different speciesthere is a greater difference between mitochondrial haplotypes from the two groups of rougheye than can be found between most other pairs of rockfish species (Gharrett et al 2005;Gharrett et al 2006). Previous comparisons of 44 allozyme loci in rougheye collected from the Gulf of Alaska and Aleutian Islands also found two sympatric types of rougheye in the southern portions of southeast Alaska (Hawkins et al 1997;Hawkins et al 2005).…”

“…(Note: the S. inermis F ST values were based upon mitochondrial DNA, and thus may be expected to be higher than estimates from nuclear DNA.) Similarly, the other measure of 0.3 was between two putative species currently grouped within S. aleutianus (Gharrett et al 2005). For reference, average F ST values (based on allozymes) are 0.222 for freshwater fishes, 0.108 for anadromous fishes, and 0.062 for marine fishes (Grant et al 1999) relatively little population genetic structure (low variation among populations relative to within).…”

A new species of Sebastes (Scorpaeniformes: Sebastidae) from the northeastern Pacific, with a redescription of the blue rockfish, S. mystinus (Jordan and Gilbert, 1881)

“…Even among brightly colored rockfishes, increased study has revealed cryptic species. Gharrett et al (2005) found 2 genetically distinct forms within the rougheye rockfish S. aleutianus (Jordan and Evermann, 1898), and those forms were later designated as the rougheye rockfish S. aleutianus and blackspotted rockfish S. melanostictus (Matsubara, 1934) (Orr and Hawkins, 2008). The historical concept of the vermilion rockfish S. miniatus (Jordan and Gilbert, 1880a) was also shown relatively recently to include 2 reproductively isolated entities (Hyde, et al, 2008).…”