A recent phylogenetic review of the genus Sebastes suggested the existence of a cryptic species of vermilion rockfish (Sebastes miniatus). To evaluate the geographical and bathymetric range of the Type 1 and Type 2 forms reported in that study, cytochrome b sequences were examined from 548 fish. Type 1 fish were found primarily south of Point Conception on reefs deeper than 100 m. Type 2 fish were common range-wide at sites shallower than 100 m. Reproductive isolation between the two types was tested using nine microsatellite loci. Estimates of genetic divergence were made using the fixation index (F(ST)) and correspondence between haplotype and genotype was tested by Bayesian population assignment and multivariate plotting of individual genotypes. Microsatellite analyses gave strong support for the presence of two distinct groups of genotypes. All fish with Type 1 haplotypes and fish with Type 2 haplotypes from < 100 m depth had genotypes unique to their haplotype group. However, most (68%) fish with Type 2 haplotypes from > 100 m depth assigned strongly to the Type 1 genotype group. Morphometric comparisons between the two genotypic groups revealed significant differences at three of the six examined measurements. Differences in both genetics, depth of occurrence, and morphology suggest these are separate species. This observation along with evidence of depth segregation in many recent species pairs led us to hypothesize a speciation model for Sebastes spp. by which the loss or truncation of a depth-related ontogenetic migration can lead to the creation of reproductively isolated populations.
Avicennia germinans L. is a widespread mangrove species occupying the west coast of Africa and the Atlantic and Pacific coasts of the Americas from the Bahamas to Brazil and Baja California to Peru. An amplified fragment length polymorphism (AFLP) molecular analysis was carried out to assess genetic architecture within this species and to evaluate the effects of the Atlantic Ocean and the Central American Isthmus (CAI) on population and regional genetic diversity and differentiation. In total, 349 polymorphic AFLP fragments were identified among 144 individuals from 14 populations from the east Atlantic, west Atlantic and east Pacific. Levels of genetic diversity varied considerably among populations, but were generally higher in populations from the east Atlantic. Regional differentiation between the Pacific coast and Atlantic populations was greater than between east and west Atlantic populations, suggesting that the CAI has had an important influence on population genetic structure in this species. The lower level of divergence of east Atlantic from west Atlantic populations suggests some dispersal across the Atlantic Ocean, although migration rates are probably low; Nm from GST equal to 0.41 and accumulation of private and rare alleles in the east Atlantic. Population differentiation did not appear to follow an isolation by distance model and has probably resulted from complex patterns of population bottlenecks, and founder events due to landscape changes during the Pleistocene, particularly in the west Atlantic. The molecular data provide no support for the treatment of east Atlantic populations as a separate species A. africana.
The Magnuson–Stevens Fishery Conservation and Management Act (MSA) requires active management of all stocks at risk of overfishing or otherwise in need of conservation and management. In the Pacific Fishery Management Council groundfish fishery management plan, about two‐thirds of the more than 90 managed stocks are currently without traditional assessments to help define stock status in relation to management targets. Stock complexes are often employed for management purposes in such situations. The guidelines issued in response to the 2006 MSA amendments defined a complex as a group of stocks with similar geographic distributions, life histories, and vulnerabilities to fisheries. This work uses productivity–susceptibility analysis (PSA) to measure the vulnerabilities of 90 managed groundfish stocks, 64 of which are currently managed within stock complexes. These stock complexes are reevaluated by first using a partitioning cluster analysis to group the stocks by depth and latitude. Vulnerability reference points are then established based on the PSA results to determine vulnerability groups of low, medium, high, and major concern within each ecological group. This method is a simple and flexible approach to incorporating vulnerability measures into stock complex designations while providing information with which to prioritize stock‐ and complex‐specific management. Received September 28, 2010; accepted February 23, 2011
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