Merluccius hubbsi (Teleostei: Merlucciidae): stock identification based on reproductive biology in the south-southeast brazilian region

The Argentine hake, Merluccius hubbsi, a demersal-pelagic species found from Rio de Janeiro, Brazil to the Tierra del Fuego, Argentina, has become an important target of the Brazilian bottom-trawler fleet since 2001. Earlier studies focusing on the species have suggested that more than one stock might occur off the Brazilian coast, in accordance with environmental features. In order to evaluate this hypothesis, fish were collected from four different areas in the Brazilian waters in which the hake is distributed, during the summers and winters of 1996-2001 and 2004, the females being used to analyze and compare spatial-temporal variations in ovarian maturation. Gonad indexes were also applied for the same purpose. Results indicate a north-south spawning gradient occurring as from summer at around 21°S to winter near 34°S, leading to the identification of two distinct stocks: one located between 21°S and 29°S (Southeastern stock) and the other between 29°S and 34°S (Southern stock), this latter shared with Uruguay and Argentina. Brazilian stocks present clear signs of overexploitation, the situation calling for an urgent solution.

Flora capensis :being a systematic description of the plants of the Cape colony, Caffraria, & Port Natal (and neighbouring territories)v. 1-7.

v. 1

Flora capensis :being a systematic description of the plants of the Cape colony, Caffraria, & Port Natal (and neighbouring territories)v. 1-7.

v. 2

Flora capensis :being a systematic description of the plants of the Cape colony, Caffraria, & Port Natal (and neighbouring territories)v. 1-7.

v. 3

Flora capensis :being a systematic description of the plants of the Cape colony, Caffraria, & Port Natal (and neighbouring territories)v. 1-7.

v. 6

Flora capensis :being a systematic description of the plants of the Cape colony, Caffraria, & Port Natal (and neighbouring territories)v. 1-7.

v. 4 pt. 2

Flora capensis :being a systematic description of the plants of the Cape colony, Caffraria, & Port Natal (and neighbouring territories)v. 1-7.

v. 4 pt. 1

Flora capensis :being a systematic description of the plants of the Cape colony, Caffraria, & Port Natal (and neighbouring territories)v. 1-7.

v. 5 pt. 1

Flora capensis :being a systematic description of the plants of the Cape colony, Caffraria, & Port Natal (and neighbouring territories)v. 1-7.

v. 5 pt. 2

Thesaurus capensis :or, illustrations of the South African flora, being figures and brief descriptions of South African plants, selected from the Dublin University Herbarium /by William H. Harvey.

v. 1

Thesaurus capensis :or, illustrations of the South African flora, being figures and brief descriptions of South African plants, selected from the Dublin University Herbarium /by William H. Harvey.

v. 2

Flora Capensis :sistens plantas promontorii Bonæ Spei Africes : secundum systema sexuale emendatum ... /Caroli Petr. Thunberg.

Pt.1-2 (1818-1820)

Flora Capensis :sistens plantas promontorii Bonae Spei Africes, secundum systema sexuale emendatum, redactas ad classes, ordines, genera et species, cum differentiis specificis, synonymis et descriptionibus /Edidit et praefatus est I. A. Schultes.

v.1

Flora Capensis :sistens plantas promontorii Bonae Spei Africes, secundum systema sexuale emendatum, redactas ad classes, ordines, genera et species, cum differentiis specificis, synonymis et descriptionibus /Edidit et praefatus est I. A. Schultes.

v.2

Genomics of the divergence continuum in an African plant biodiversity hotspot, I: drivers of population divergence in Restio capensis (Restionaceae).

Understanding the drivers of population divergence, speciation and species persistence is of great interest to molecular ecology, especially for species-rich radiations inhabiting the world's biodiversity hotspots. The toolbox of population genomics holds great promise for addressing these key issues, especially if genomic data are analysed within a spatially and ecologically explicit context. We have studied the earliest stages of the divergence continuum in the Restionaceae, a species-rich and ecologically important plant family of the Cape Floristic Region (CFR) of South Africa, using the widespread CFR endemic Restio capensis (L.) H.P. Linder & C.R. Hardy as an example. We studied diverging populations of this morphotaxon for plastid DNA sequences and >14 400 nuclear DNA polymorphisms from Restriction site Associated DNA (RAD) sequencing and analysed the results jointly with spatial, climatic and phytogeographic data, using a Bayesian generalized linear mixed modelling (GLMM) approach. The results indicate that population divergence across the extreme environmental mosaic of the CFR is mostly driven by isolation by environment (IBE) rather than isolation by distance (IBD) for both neutral and non-neutral markers, consistent with genome hitchhiking or coupling effects during early stages of divergence. Mixed modelling of plastid DNA and single divergent outlier loci from a Bayesian genome scan confirmed the predominant role of climate and pointed to additional drivers of divergence, such as drift and ecological agents of selection captured by phytogeographic zones. Our study demonstrates the usefulness of population genomics for disentangling the effects of IBD and IBE along the divergence continuum often found in species radiations across heterogeneous ecological landscapes.