Hot alkaline lysis gDNA extraction from formalin-fixed archival tissues.

Formalin fixation of natural history specimens and histopathological material has historically been viewed as an impediment to successful genomic analysis. However, the development of extraction methods specifically tailored to contend with heavily crosslinked archival tissues, re-contextualises millions of previously overlooked specimens as viable molecular assets. Here, we present an easy-to-follow protocol for screening archival wet specimens for molecular viability and subsequent genomic DNA extraction suitable for sequencing. The protocol begins with non-destructive assessment of specimen degradation and preservation media conditions to allow both museum curators and researchers to select specimens most likely to yield an acceptable proportion (20-60%) of mappable endogenous DNA during short-read DNA sequencing. The extraction protocol uses hot alkaline lysis in buffer (0.1M NaOH, 1% SDS, pH 13) to simultaneously lyse and de-crosslink the tissue. To maximise DNA recovery, phenol:chloroform extraction is coupled with a small-fragment optimised SPRI bead clean up. Applied to well-preserved archival tissues, the protocol can yield 1-2 µg DNA per 50 mg of tissue with mean fragment sizes typically ranging from 50-150 bp, which is suitable to recover genomic DNA sufficient to reconstruct complete mitochondrial genomes and achieve up to 25X nuclear genome coverage. We provide guidance for read mapping to a reference genome and discuss the limitations of relying on small fragments for SNP genotyping and de novo genome assembly. This protocol opens the door to broader-scale genetic and phylogenetic analysis of historical specimens, contributing to a deeper understanding of evolutionary trends and adaptation in response to changing environments.

Stepping up to genome scan allows stock differentiation in the worldwide distributed blue shark Prionace glauca.

The blue shark Prionace glauca is a top predator with one of the widest geographical distributions of any shark species. It is classified as Critically Endangered in the Mediterranean Sea, and Near Threatened globally. Previous genetic studies did not reject the null hypothesis of a single global population. The blue shark was proposed as a possible archetype of the "grey zone of population differentiation," coined to designate cases where population structure may be too recent or too faint to be detected using a limited set of markers. Here, blue shark samples collected throughout its global range were sequenced using a specific RAD method (DArTseq), which recovered 37,655 genome-wide single nucleotide polymorphisms (SNPs). Two main groups emerged, with Mediterranean Sea and northern Atlantic samples (Northern population) differentiated significantly from the Indo-west Pacific samples (Southern population). Significant pairwise FST values indicated further genetic differentiation within the Atlantic Ocean, and between the Atlantic Ocean and the Mediterranean Sea. Reconstruction of recent demographic history suggested divergence between Northern and Southern populations occurred about 500 generations ago and revealed a drastic reduction in effective population size from a large ancestral population. Our results illustrate the power of genome scans to detect population structure and reconstruct demographic history in highly migratory marine species. Given that the management plans of the blue shark (targeted or bycatch) fisheries currently assume panmictic regional stocks, we strongly recommend that the results presented here be considered in future stock assessments and conservation strategies.

Low levels of sibship encourage use of larvae in western Atlantic bluefin tuna abundance estimation by close-kin mark-recapture.

Globally, tunas are among the most valuable fish stocks, but are also inherently difficult to monitor and assess. Samples of larvae of Western Atlantic bluefin tuna Thunnus thynnus (Linnaeus, 1758) from standardized annual surveys in the northern Gulf of Mexico provide a potential source of "offspring" for close-kin mark-recapture (CKMR) estimates of abundance. However, the spatial patchiness and highly skewed numbers of larvae per tow suggest sampled larvae may come from a small number of parents, compromising the precision of CKMR. We used high throughput genomic profiling to study sibship within and among larval tows from the 2016 standardized Gulf-wide survey compared to targeted sampling carried out in 2017. Full- and half-siblings were found within both years, with 12% of 156 samples in 2016 and 56% of 317 samples in 2017 having at least one sibling. There were also two pairs of cross cohort half-siblings. Targeted sampling increased the number of larvae collected per sampling event but resulted in a higher proportion of siblings. The combined effective sample size across both years was about 75% of the nominal size, indicating that Gulf of Mexico larval collections could be a suitable source of juveniles for CKMR in Western Atlantic bluefin tuna.

Lack of genetic differentiation in yellowfin tuna has conservation implications in the Eastern Pacific Ocean.

Yellowfin tuna, Thunnus albacares, is an important global fishery and of particular importance in the Eastern Pacific Ocean (EPO). According to the 2019 Inter-American Tropical Tuna Commission (IATTC) assessment, yellowfin tuna within the EPO is a single stock, and is being managed as one stock. However, previous studies indicate site fidelity, or limited home ranges, of yellowfin tuna which suggests the potential for multiple yellowfin tuna stocks within the EPO, which was supported by a population genetic study using microsatellites. If numerous stocks are present, management at the wrong spatial scales could cause the loss of minor yellowfin tuna populations in the EPO. In this study we used double digestion RADseq to assess the genetic structure of yellowfin tuna in the EPO. A total of 164 yellowfin tuna from Cabo San Lucas, México, and the Galápagos Islands and Santa Elena, Ecuador, were analysed using 18,011 single nucleotide polymorphisms. Limited genetic differentiation (FST = 0.00058-0.00328) observed among the sampling locations (México, Ecuador, Peru, and within Ecuador) is consistent with presence of a single yellowfin tuna population within the EPO. Our findings are consistent with the IATTC assessment and provide further evidence of the need for transboundary cooperation for the successful management of this important fishery throughout the EPO.

Prevalence and predictors of difficult vascular anatomy in forearm artery access for coronary angiography and PCI.

Transradial access has established as preferred access for cardiac catheterization. Difficult vascular anatomy (DVA) is a noticeable threat to procedural success. We retrospectively analyzed 1397 consecutive cardiac catheterizations to estimate prevalence and identify predictors of DVA. In the subclavian-innominate-aortic-region (SIAR), DVA was causing failure in 2.4% during right-sided vs. 0.7% in left-sided forearm-artery-access (FAA) attempts (χ2 = 5.1, p = 0.023). Independent predictors were advanced age [odds ratio (OR) 1.44 per 10-year increase, 95% confidence interval (CI) 1.15 to 1.80, p = 0.001] and right FAA (OR 2.52, 95% CI 1.72 to 3.69, p < 0.001). In the radial-ulnar-brachial region (RUBR), DVA was causing failure in 2.5% during right-sided vs. 1.7% in left-sided FAA (χ2 = 0.77, p = 0.38). Independent predictors were age (OR 1.28 per 10-year increase, 95% CI 1.01 to 1.61, p = 0.04), lower height (OR 1.56 per 10-cm decrease, 95% CI 1.13 to 2.15, p = 0.008) and left FAA (OR 2.15, 95% CI 1.45 to 3.18, p < 0.001). Bilateral DVA was causing procedural failure in 0.9% of patients. The prevalence of bilateral DVA was rare. Predictors in SIAR were right FAA and advanced age and in RUBR, left FAA, advanced age and lower height. Gender, arterial hypertension, body mass, STEMI and smoking were not associated with DVA.

Standardized Forearm Angiography Increases Procedural Success Rates of Coronary Angiography and PCI: A Retrospective Analysis of an all-Comers Patient Cohort in a Real-Life Scenario.

Background: There is a consensus, that Transradial-Access (TRA) for coronary procedures should be preferred over Transfemoral-Access (TFA). Previously, Forearm-Artery-Angiography (FA) was mainly performed when difficulties during the advancement of the guidewire/-catheter were encountered. We explored the implication of a Standardized Forearm-Angiography (SFA) on procedural success rates of TRA under real-world conditions. Methods: In a single-center study, an all-comers-cohort of 1191 consecutive cases during 1/2020-12/2020 were assessed retrospectively. Primary TFA rates, crossover to TFA, reasons for Forearm-Artery-Access (FAA) failure, the prevalence of kinking at the level of the forearm and the occurrence of vascular complications were analyzed. Major forearm side branches including the common interosseus artery were assessed via SFA. Results: In 1191 consecutive procedures, primary FAA access was attempted in 97.9% of cases. Crossover to TFA after a primary or secondary FAA attempt was necessary in 2.8%. Severe kinking was the most frequent cause of FAA failure and occurred in 3.0% of attempts. A second or third FAA attempt to avoid TFA was successful in 81%. Severe kinking at the level of the forearm was reported in 1.8% of procedures. Conclusion: This is the first study to provide detailed success rates of a primary FAA strategy combined with a Standardized-Forearm-Angiography (SFA) in an all-comers-cohort. While severe kinking proved to be a rare but relevant challenge for FAA success, the prevalence of arterial spasm was marginal. Multiple attempts of FAA to avoid TFA might be safe possibly due to collateral blood supply by the common interosseus artery.

Sample size requirements for genetic studies on yellowfin tuna.

In population genetics, the amount of information for an analytical task is governed by the number of individuals sampled and the amount of genetic information measured on each of those individuals. In this work, we assessed the numbers of individual yellowfin tuna (Thunnus albacares) and genetic markers required for ocean-basin scale inferences. We assessed this for three distinct data analysis tasks that are often employed: testing for differences between genetic profiles; stock delineation, and; assignment of individuals to stocks. For all analytical tasks, we used real (not simulated) data from four sampling locations that span the tropical Pacific Ocean. Whilst spatially separated, the genetic differences between the sampling sites were not substantial, a maximum of approximately Fst = 0.02, which is quite typical of large pelagic fish. We repeatedly sub-sampled the data, mimicking a new survey, and performed the analyses. False positive rates were also assessed by re-sampling and randomly assigning fish to groups. Varying the sample sizes indicated that some analytical tasks, namely profile testing, required relatively few individuals per sampling location (n ≳ 10) and single nucleotide polymorphisms (SNPs, m ≳ 256). Stock delineation required more individuals per sampling location (n ≳ 25). Assignment of fish to sampling locations required substantially more individuals, more in fact than we had available (n > 50), although this sample size could be reduced to n ≳ 30 when individual fish were assumed to belong to one of the groups sampled. With these results, designers of molecular ecological surveys for yellowfin tuna, and users of information from them, can assess whether the information content is adequate for the required inferential task.

A review of the fisheries, life history and stock structure of tropical tuna (skipjack Katsuwonus pelamis, yellowfin Thunnus albacares and bigeye Thunnus obesus) in the Indian Ocean.

Skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) tuna are the target species of tropical tuna fisheries in the Indian Ocean, with high commercial value in the international market. High fishing pressure over the past three decades has raised concerns about their sustainability. Understanding life history strategies and stock structure is essential to determine species resilience and how they might respond to exploitation. Here we provide a comprehensive review of available knowledge on the biology, ecology, and stock structure of tropical tuna species in the Indian Ocean. We describe the characteristics of Indian Ocean tropical tuna fisheries and synthesize skipjack, yellowfin, and bigeye tuna key life history attributes such as biogeography, trophic ecology, growth, and reproductive biology. In addition, we evaluate the available literature about their stock structure using different approaches such as analysis of fisheries data, genetic markers, otolith microchemistry and tagging, among others. Based on this review, we conclude that there is a clear lack of ocean basin-scale studies on skipjack, yellowfin and bigeye tuna life history, and that regional stock structure studies indicate that the panmictic population assumption of these stocks should be investigated further. Finally, we identify specific knowledge gaps that should be addressed with priority to ensure a sustainable and effective management of these species.

Accounting for kin sampling reveals genetic connectivity in Tasmanian and New Zealand school sharks, Galeorhinus galeus.

Fishing represents a major problem for conservation of chondrichthyans, with a quarter of all species being overexploited. School sharks, Galeorhinus galeus, are targeted by commercial fisheries in Australia and New Zealand. The Australian stock has been depleted to below 20% of its virgin biomass, and the species is recorded as Conservation Dependent within Australia. Individuals are known to move between both countries, but it is disputed whether the stocks are reproductively linked. Accurate and unbiased determination of stock and population connectivity is crucial to inform effective management. In this study, we assess the genetic composition and population connectivity between Australian and New Zealand school sharks using genome-wide SNPs, while accounting for non-random kin sampling. Between 2009 and 2013, 88 neonate and juvenile individuals from Tasmanian and New Zealand nurseries were collected and genotyped. Neutral loci were analyzed to detect fine-scale signals of reproductive connectivity. Seven full-sibling groups were identified and removed for unbiased analysis. Based on 6,587 neutral SNPs, pairwise genetic differentiation from Tasmanian and New Zealand neonates was non-significant (F ST = 0.0003, CI95 = [-0.0002, 0.0009], p = 0.1163; D est = 0.0006 ± 0.0002). This pattern was supported by clustering results. In conclusion, we show a significant effect of non-random sampling of kin and identify fine-scale reproductive connectivity between Australian and New Zealand school sharks. OPEN RESEARCH BADGES: This article has earned an Open Data Badge for making publicly available the digitally-shareable data necessary to reproduce the reported results. The data is available at https://doi.org/10.5061/dryad.pd8612j.

Robust estimates of a high Ne/N ratio in a top marine predator, southern bluefin tuna.

Genetic studies of several marine species with high fecundity have produced "tiny" estimates (≤10-3) of the ratio of effective population size (Ne) to adult census size (N), suggesting that even very large populations might be at genetic risk. A recent study using close-kin mark-recapture methods estimated adult abundance at N ≈ 2 × 106 for southern bluefin tuna (SBT), a highly fecund top predator that supports a lucrative (~$1 billion/year) fishery. We used the same genetic and life history data (almost 13,000 fish collected over 5 years) to generate genetic and demographic estimates of Ne per generation and Nb (effective number of breeders) per year and the Ne/N ratio. Demographic estimates, which accounted for age-specific vital rates, skip breeding, variation in fecundity at age, and persistent individual differences in reproductive success, suggest that Ne/N is >0.1 and perhaps about 0.5. The genetic estimates supported this conclusion. Simulations using true Ne = 5 × 105 (Ne/N = 0.25) produced results statistically consistent with the empirical genetic estimates, whereas simulations using Ne = 2 × 104 (Ne/N = 0.01) did not. Our results show that robust estimates of Ne and Ne/N can be obtained for large populations, provided sufficiently large numbers of individuals and genetic markers are used and temporal replication (here, 5 years of adult and juvenile samples) is sufficient to provide a distribution of estimates. The high estimated Ne/N ratio in SBT is encouraging and suggests that the species will not be compromised by a lack of genetic diversity in responding to environmental change and harvest.

Reliably discriminating stock structure with genetic markers: Mixture models with robust and fast computation.

Delineating naturally occurring and self-sustaining subpopulations (stocks) of a species is an important task, especially for species harvested from the wild. Despite its central importance to natural resource management, analytical methods used to delineate stocks are often, and increasingly, borrowed from superficially similar analytical tasks in human genetics even though models specifically for stock identification have been previously developed. Unfortunately, the analytical tasks in resource management and human genetics are not identical-questions about humans are typically aimed at inferring ancestry (often referred to as "admixture") rather than breeding stocks. In this article, we argue, and show through simulation experiments and an analysis of yellowfin tuna data, that ancestral analysis methods are not always appropriate for stock delineation. In this work, we advocate a variant of a previously introduced and simpler model that identifies stocks directly. We also highlight that the computational aspects of the analysis, irrespective of the model, are difficult. We introduce some alternative computational methods and quantitatively compare these methods to each other and to established methods. We also present a method for quantifying uncertainty in model parameters and in assignment probabilities. In doing so, we demonstrate that point estimates can be misleading. One of the computational strategies presented here, based on an expectation-maximization algorithm with judiciously chosen starting values, is robust and has a modest computational cost.

Inferring contemporary and historical genetic connectivity from juveniles.

Measuring population connectivity is a critical task in conservation biology. While genetic markers can provide reliable long-term historical estimates of population connectivity, scientists are still limited in their ability to determine contemporary patterns of gene flow, the most practical time frame for management. Here, we tackled this issue by developing a new approach that only requires juvenile sampling at a single time period. To demonstrate the usefulness of our method, we used the Speartooth shark (Glyphis glyphis), a critically endangered species of river shark found only in tropical northern Australia and southern Papua New Guinea. Contemporary adult and juvenile shark movements, estimated with the spatial distribution of kin pairs across and within three river systems, was contrasted with historical long-term connectivity patterns, estimated from mitogenomes and genome-wide SNP data. We found strong support for river fidelity in juveniles with the within-cohort relationship analysis. Male breeding movements were highlighted with the cross-cohort relationship analysis, and female reproductive philopatry to the river systems was revealed by the mitogenomic analysis. We show that accounting for juvenile river fidelity and female philopatry is important in population structure analysis and that targeted sampling in nurseries and juvenile aggregations should be included in the genomic toolbox of threatened species management.

Absolute abundance of southern bluefin tuna estimated by close-kin mark-recapture.

Southern bluefin tuna is a highly valuable, severely depleted species, whose abundance and productivity have been difficult to assess with conventional fishery data. Here we use large-scale genotyping to look for parent-offspring pairs among 14,000 tissue samples of juvenile and adult tuna collected from the fisheries, finding 45 pairs in total. Using a modified mark-recapture framework where 'recaptures' are kin rather than individuals, we can estimate adult abundance and other demographic parameters such as survival, without needing to use contentious fishery catch or effort data. Our abundance estimates are substantially higher and more precise than previously thought, indicating a somewhat less-depleted and more productive stock. More broadly, this technique of 'close-kin mark-recapture' has widespread utility in fisheries and wildlife conservation. It estimates a key parameter for management-the absolute abundance of adults-while avoiding the expense of independent surveys or tag-release programmes, and the interpretational problems of fishery catch rates.

Suppression and restoration of primordial germ cell marker gene expression in channel catfish, Ictalurus punctatus, using knockdown constructs regulated by copper transport protein gene promoters: Potential for reversible transgenic sterilization.

Complementary DNA overexpression and short hairpin RNA interference approaches were evaluated for decreasing expression of primordial germ cell (PGC) marker genes and thereby sterilizing channel catfish, Ictalurus punctatus, by delivering knockdown constructs driven by a constitutive promoter from yeast and a copper transport protein gene into fish embryos by electroporation. Two PGC marker genes, nanos and dead end, were the target knockdown genes, and their expressions, along with that of an off-target gene, vasa, were evaluated temporally using real-time polymerase chain reaction. Copper sulfate was evaluated as a repressor compound. Some of the constructs knocked down PGC marker gene expression, and some of the constructs were partially repressed by application of 0.1-ppm copper sulfate. When the rate of sexual maturity was compared for three-year-old broodfish that had been exposed to the sterilizing constructs during embryologic development and controls that had not been exposed, several treatments had reduced sexual maturity for the exposed fish. Of two promoter systems evaluated, the one which had been designed to be less sensitive to copper generally was more effective at achieving sterilization and more responsive to repression. Knockdown constructs based on 3' nanos short hairpin RNA interference appeared to result in the best repression and restoration of normal sexual maturity. We conclude that these copper-based systems exhibited good potential for repressible transgenic sterilization. Optimization of this system could allow environmentally safe application of transgenic technology and might be applicable to other applications for aquatic organisms.

[Differential diagnosis of tachycardia with a broad QRS-complex]. / Differenzialdiagnostik der Breitkomplex-Tachykardie.

INTRODUCTION: The electrocardiographic (ECG) differential diagnosis of tachycardia with a broad QRS complex (BCT) represents a challenge for physicians but is important for adequate treatment and risk evaluation. Differentiated algorithms have been established and can increase the specificity of the diagnosis in individual patients but are often hampered by complexity and yield a pragmatic ECG approach. METHODS AND RESULTS: Irregular BCTs (irregular R-R distances) despite the patient being hemodynamically stable are almost always due to atrial fibrillation with bundle branch block (pre-existing or functional) or conduction via accessory pathways. In contrast, sustained polymorphic ventricular tachycardia (VT) is always associated with hemodynamic collapse. In regular BCT the following mechanisms must be differentiated: (1) VT, (2) supraventricular tachycardia (SVT) with bundle branch block or (3) SVT with pre-excitation via accessory pathways, e.g. Wolff-Parkinson-White (WPW) syndrome. The presence of an underlying structural heart disease, specifically a history of myocardial infarction is suggestive of VT. For a differentiated analysis in hemodynamically stable patients a 12-lead ECG is essential. CONCLUSION: Identification of signs of atrioventricular (AV) dissociation or a negative precordial concordance of QRS are indicative of VT. In V1 positive BCTs a positive precordial concordance, QRS width > 140 ms, superiorly directed QRS axis, monophasic or biphasic QRS complexes in V1 and deep S wave in V6 are indications of a VT. In V1 negative BCTs, QRS width > 160 ms, right-sided QRS axis, broad R peak (> 40 ms) in V1/V2, slurred S downstroke in V1/V2 and any Q peak in V6 are all indications of VT as the mechanism.

Effects of transgenic sterilization constructs and their repressor compounds on hatch, developmental rate and early survival of electroporated channel catfish embryos and fry.

Channel catfish (Ictalurus punctatus) embryos were electroporated with sterilization constructs targeting primordial germ cell proteins or with buffer. Some embryos then were treated with repressor compounds, cadmium chloride, copper sulfate, sodium chloride or doxycycline, to prevent expression of the transgene constructs. Promoters included channel catfish nanos and vasa, salmon transferrin (TF), modified yeast Saccharomyces cerevisiae copper transport protein (MCTR) and zebrafish racemase (RM). Knock-down systems were the Tet-off (nanos and vasa constructs), MCTR, RM and TF systems. Knock-down genes included shRNAi targeting 5' nanos (N1), 3' nanos (N2) or dead end (DND), or double-stranded nanos RNA (dsRNA) for overexpression of nanos mRNA. These constructs previously were demonstrated to knock down nanos, vasa and dead end, with the repressors having variable success. Exogenous DNA affected percentage hatch (% hatch), as all 14 constructs, except for the TF dsRNA, TF N1 (T), RM DND (C), vasa DND (C), vasa N1 (C) and vasa N2 (C), had lower % hatch than the control electroporated with buffer. The MCTR and RM DND (T) constructs resulted in delayed hatch, and the vasa and nanos constructs had minimal effects on time of hatch (P < 0.05). Cadmium chloride appeared to counteract the slow development caused by the TF constructs in two TF treatments (P < 0.05). The 4 ppt sodium chloride treatment for the RM system decreased % hatch (P < 0.05) and slowed development. In the case of nanos constructs, doxycycline greatly delayed hatch (P < 0.05). Adverse effects of the transgenes and repressors continued for several treatments for the first 6 days after hatch, but only in a few treatments during the next 10 days. Repressors and gene expression impacted the yield of putative transgenic channel catfish fry, and need to be considered and accounted for in the hatchery phase of producing transgenically sterilized catfish fry and their fertile counterparts. This fry output should be considered to ensure that sufficient numbers of transgenic fish are produced for future applications and for defining repressor systems that are the most successful.

Whole mitogenome of the Endangered dwarf sawfish Pristis clavata (Rajiformes: Pristidae).

In this study, we describe the first complete mitochondrial sequence for the Endangered dwarf sawfish Pristis clavata. The base composition of the 16,804 bp long mitogenome is 31.9% A, 26.5% C, 13.3% G and 28.3% T and the gene arrangement and transcriptional direction are the same as those found in most vertebrates. All protein-coding genes start with ATG except the COI gene, which starts with GTG. Stop codons include incomplete T, AGG and TAA; however, TAG is not found in the mitogenome of this euryhaline elasmobranch species.

Complete mitogenomic sequence of the Critically Endangered Northern River Shark Glyphis garricki (Carcharhiniformes: Carcharhinidae).

In this study we describe the first complete mitochondrial sequence for the Critically Endangered Northern River shark Glyphis garricki. The complete mitochondrial sequence is 16,702 bp in length, contains 37 genes and one control region with the typical gene order and transcriptional direction of vertebrate mitogenomes. The overall base composition is 31.5% A, 26.3% C, 12.9% G and 29.3% T. The length of 22 tRNA genes ranged from 68 (tRNA-Ser2 and tRNA-Cys) to 75 (tRNA-Leu1) bp. The control region of G. garricki was 1067 bp in length with high A+T (67.9%) and poor G (12.6%) content. The mitogenomic characters (base composition, codon usage and gene length) of G. garricki were very similar to Glyphis glyphis.

Mitogenomics of the Speartooth Shark challenges ten years of control region sequencing.

BACKGROUND: Mitochondrial DNA markers have long been used to identify population boundaries and are now a standard tool in conservation biology. In elasmobranchs, evolutionary rates of mitochondrial genes are low and variation between distinct populations can be hard to detect with commonly used control region sequencing or other single gene approaches. In this study we sequenced the whole mitogenome of 93 Critically Endangered Speartooth Shark Glyphis glyphis from the last three river drainages they inhabit in northern Australia. RESULTS: Genetic diversity was extremely low (π =0.00019) but sufficient to demonstrate the existence of barriers to gene flow among river drainages (AMOVA Φ ST =0.28283, P <0.00001). Surprisingly, the comparison with single gene sub-datasets revealed that ND5 and 12S were the only ones carrying enough information to detect similar levels of genetic structure. The control region exhibited only one mutation, which was not sufficient to detect any structure among river drainages. CONCLUSIONS: This study strongly supports the use of single river drainages as discrete management units for the conservation of G. glyphis. Furthermore when genetic diversity is low, as is often the case in elasmobranchs, our results demonstrate a clear advantage of using the whole mitogenome to inform population structure compared to single gene approaches. More specifically, this study questions the extensive use of the control region as the preferential marker for elasmobranch population genetic studies and whole mitogenome sequencing will probably uncover a large amount of cryptic population structure in future studies.