Strong genetic isolation despite wide distribution in a commercially exploited coastal shark

Hull, Kelvin L.; Asbury, Tamaryn A.; Silva, Charlene da; Dicken, ML; Veríssimo, Ana; Farrell, Edward D.; Mariani, Stefano; Mazzoldi, Carlotta; Marino, Ilaria A. M.; Zane, Lorenzo; Merwe, Aletta E. Bester‐van der

doi:10.1007/s10750-019-03982-8

Cited by 8 publications

(5 citation statements)

References 67 publications

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“…The Benguela Upwelling zone is known to shape population structure in a number of teleost fish, e.g., Atractoscion aequidens (Henriques et al, 2014), bluefish Pomatomus saltatrix (Reid et al, 2016) and Leerfish Lichia amia (Henriques et al, 2012), leading to deep divergences and even cryptic speciation (Gwilliam et al, 2018). Similarly, smaller coastal elasmobranchs also tend to appear more fragmented and inhibited by oceanographic barriers in the region and elsewhere (Bester-van der Hull et al, 2019;Maduna et al, 2017;Veríssimo et al, 2017). However, body size alone is not always a good predictor for genetic connectivity in elasmobranchs as depth distribution, habitat, environmental tolerance and reproductive behaviour can also play a crucial role (Hirschfeld et al, 2021) and Camarada (2007) reported only two C. brachyurus crossing the Lüderitz Upwelling Cell out of 10,000 tagged sharks.…”

Section: Discussionmentioning

confidence: 99%

“…This was based on the species distribution disjunction previously observed in the Lüderitz area and an apparent difference in breeding seasonality. The Lüderitz area's influence on genetic breaks and species divergence due to the cold‐water upwelling formation characterizing the region (Lutjeharms & Meeuwis, 1987 ) is known for other elasmobranchs and marine organisms (Henriques et al., 2014 , 2015 ; Hull et al., 2019 ). However, given the highly migratory behaviour of this species and based on previous investigations, extensive gene flow along coastal areas is expected (Benavides et al., 2011 ; Huveneers et al., 2021 ; Junge et al., 2019 ).…”

Section: Introductionmentioning

confidence: 99%

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Local adaptation with gene flow in a highly dispersive shark

Klein,

Maduna,

Dicken

et al. 2023

Evolutionary Applications

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Adaptive divergence in response to environmental clines are expected to be common in species occupying heterogeneous environments. Despite numerous advances in techniques appropriate for non‐model species, gene–environment association studies in elasmobranchs are still scarce. The bronze whaler or copper shark (Carcharhinus brachyurus) is a large coastal shark with a wide distribution and one of the most exploited elasmobranchs in southern Africa. Here, we assessed the distribution of neutral and adaptive genomic diversity in C. brachyurus across a highly heterogeneous environment in southern Africa based on genome‐wide SNPs obtained through a restriction site‐associated DNA method (3RAD). A combination of differentiation‐based genome‐scan (outflank) and genotype–environment analyses (redundancy analysis, latent factor mixed models) identified a total of 234 differentiation‐based outlier and candidate SNPs associated with bioclimatic variables. Analysis of 26,299 putatively neutral SNPs revealed moderate and evenly distributed levels of genomic diversity across sites from the east coast of South Africa to Angola. Multivariate and clustering analyses demonstrated a high degree of gene flow with no significant population structuring among or within ocean basins. In contrast, the putatively adaptive SNPs demonstrated the presence of two clusters and deep divergence between Angola and all other individuals from Namibia and South Africa. These results provide evidence for adaptive divergence in response to a heterogeneous seascape in a large, mobile shark despite high levels of gene flow. These results are expected to inform management strategies and policy at the national and regional level for conservation of C. brachyurus populations.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Local adaptation with gene flow in a highly dispersive shark

Klein,

Maduna,

Dicken

et al. 2023

Evolutionary Applications

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“…In turn, recent genetic studies have shown strong genetic variation of M. mustelus along its geographical distribution range. This is the case for populations from the Mediterranean Sea, and the west and southern African coasts, including fine‐scale population structure in each region, but a lack of correlation between genetic and geographical distance (Hull et al, 2019). A similar outcome of genetic differentiation (large genetic variation) was observed between populations from the south‐western Indian and south‐eastern Atlantic Oceans (Bitalo et al, 2015; Maduna et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Distribution and population structure of the smooth‐hound shark, Mustelus mustelus (Linnaeus, 1758), across an oceanic archipelago: Combining several data sources to promote conservation

Espino

González

Bosch

et al. 2022

Ecology and Evolution

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Sharks play a key role in the structure and functioning of marine ecosystems. More ecological information is essential to implement responsible management and conservation actions on this fauna, particularly at a regional level for threatened species. Mustelus mustelus is widely found in the eastern Atlantic Ocean and catalogued as “Vulnerable” by the IUCN European assessment. In this study, data on the distribution and population structure of this species across the islands of the Canarian archipelago, located along an east to west gradient in the north‐eastern Atlantic, were collected by taking advantage of “Local Ecological Knowledge,” in terms of sightings in coastal waters and long‐term imprints on the local gastronomic heritage, and decadal fisheries landings. Both sources of quantitative data (sightings and fisheries landings) demonstrated that adults of M. mustelus has a significantly larger presence in the eastern and central, than in the western islands of the archipelago. This is also reflected on local gastronomic legacies, with a larger number of recipes in the eastern and central islands. Adult smooth‐hound sharks were significantly more observed in sandy and sandy‐rocky bottoms, with individuals seen throughout the entire year, whereas juveniles aggregate on very shallow waters in spring and summer. Such aggregations require a special management strategy, as they play a key role in critical life stages; these sites should be protected from human perturbations. We also suggest a temporal fishing ban between April and October, when individuals tend to concentrate on nearshore waters. Because of the large differences in presence of this shark among the Canary Islands, management of the species should be adapted to the specific peculiarities of each island, rather than adopting a management policy at the entire archipelago‐scale. Overall, this study sets the basis for further investigation to promote conservation of this vulnerable shark in the study region.

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“…and South African M. mustelus sampling populations (Hull et al, 2019), suggesting that these constitute different stocks. The authors argued that the ABFZ potentially acts a hydrodynamic barrier, as has been observed in teleost fish (Henriques et al, 2014;Reid et al, 2016)…”

Section: Genetic Analyses Revealed High Genetic Differentiation Between Angolanmentioning

confidence: 97%

Site fidelity and shallow genetic structure in the common smooth‐hound shark Mustelus mustelus confirmed by tag‐recapture and genetic data

Klein

Asbury

Silva³

et al. 2021

Journal of Fish Biology

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The common smooth-hound shark, Mustelus mustelus, is a widely distributed demersal shark under heavy exploitation from various fisheries throughout its distribution range. To assist in the development of appropriate management strategies, the authors evaluate stock structure, site fidelity and movement patterns along the species' distribution in southern Africa based on a combination of molecular and long-term tag-recapture data. Eight species-specific microsatellite markers (N = 73) and two mitochondrial genes, nicotinamide adenine dehydrogenase subunit 4 and control region (N = 45), did not reveal any significant genetic structure among neighbouring sites. Nonetheless, tagging data demonstrate a remarkable degree of site fidelity with 76% of sharks recaptured within 50 km of the original tagging location. On a larger geographic scale, dispersal is governed by oceanographic features as demonstrated by the lack of movements across the Benguela-Agulhas transition zone separating the South-East Atlantic Ocean (SEAO) and South-West Indian Ocean (SWIO) populations. Microsatellite data supported very shallow ocean-based structure (SEAO and SWIO) and historical southward gene flow following the Agulhas Current, corroborating the influence of this dynamic oceanographic system on gene flow. Moreover, no movements between Namibia and South Africa were observed, indicating that the Lüderitz upwelling formation off the Namibian coast acts as another barrier to dispersal and gene flow. Overall, these results show that dispersal and stock structure of M. mustelus are governed by a combination of behavioural traits and oceanographic features such as steep temperature gradients, currents and upwelling systems.

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Strong genetic isolation despite wide distribution in a commercially exploited coastal shark

Cited by 8 publications

References 67 publications

Local adaptation with gene flow in a highly dispersive shark

Local adaptation with gene flow in a highly dispersive shark

Distribution and population structure of the smooth‐hound shark, Mustelus mustelus (Linnaeus, 1758), across an oceanic archipelago: Combining several data sources to promote conservation

Site fidelity and shallow genetic structure in the common smooth‐hound shark Mustelus mustelus confirmed by tag‐recapture and genetic data

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