Two's company: Monozygotic twinning in the small‐spotted catshark (Scyliorhinus canicula)

Journal of Fish Biology, Journal Year: 2025, Volume and Issue: unknown

Published: April 8, 2025

Abstract Developmental abnormalities in elasmobranchs (sharks and rays) are rarely documented, with reported cases primarily involving fin or cranial deformities. Monozygotic twinning, the formation of identical twins from a single zygote, is particularly rare these species has been observed overwhelmingly viviparous elasmobranchs. Here, we document case monozygotic twinning an oviparous shark, Small‐spotted Catshark Scyliorhinus canicula (Linneaus, 1758). This was characterized by two embryos connected to yolk sac via separate stalks within egg capsule. The exhibited normal development until mortality at developmental Stage 31 (Ballard et al., 1993) stage 4 (Musa 2018), likely due stressors such as oxidative stress allostatic overload, resulting shared resources first confirmed instance elasmobranch twins, highlighting plausible challenges polyembryony These findings underscore importance understanding reproductive their implications for fecundity, light ongoing anthropogenic pressures that threaten populations globally.

Language: Английский

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Phylogenetic analysis of viviparity, matrotrophy, and other reproductive patterns in chondrichthyan fishes

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Journal Year: 2024, Volume and Issue: 99(4), P. 1314 - 1356

Published: April 1, 2024

ABSTRACT The reproductive diversity of extant cartilaginous fishes (class Chondrichthyes) is extraordinarily broad, reflecting more than 400 million years evolutionary history. Among their many notable specialisations are viviparity (live‐bearing reproduction) and matrotrophy (maternal provision nutrients during gestation). However, attempts to understand the evolution these traits have yielded highly discrepant conclusions. Here, we compile analyse current knowledge on in Chondrichthyes with particular foci frequency, phylogenetic distribution, directionality changes modes reproduction. To characterise transformations, amassed largest empirical data set parameters date covering nearly 800 species analysed it via a comprehensive molecular‐based phylogeny. Our reconstructions indicated that ancestral pattern for ‘short single oviparity’ (as found holocephalans) which females lay successive clutches (broods) one or two eggs. Viviparity has originated at least 12 times, 10 origins among sharks, batoids, (based published evidence) another potential origin fossil holocephalan. Substantial evolved six including placentotrophy, three separate oophagy (egg ingestion), histotrophy (uptake uterine secretions). In clades, placentation was replaced by histotrophy. Unlike past reconstructions, our analysis reveals no evidence ever reverted oviparity this group. Both arisen variety sequences. addition, given rise distinct egg‐laying patterns increased clutch (brood) size and/or involved deposition eggs advanced stages development. Geologically, oviparous arose Paleozoic. Most Mesozoic, while few represented low taxonomic levels Cenozoic origin. Coupled other recent work, review points way towards an emerging consensus chondrichthyans offering basis future functional analyses. This also contributes conservation efforts highlighting taxa whose reflect distinctive trajectories deserve special protection further investigation.

Language: Английский

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The origins and drivers of sexual size dimorphism in sharks

Ecology and Evolution, Journal Year: 2024, Volume and Issue: 14(3)

Published: March 1, 2024

Abstract While sexual size dimorphism (SSD) is abundant in nature, there huge variation both the intensity and direction of SSD. SSD results from a combination selection for large male size, fecundity female ecological either. In most vertebrates, it male–male competition that primarily underlies this study, we test four hypotheses regarding adaptive value sharks—considering potential each fecundity, sexual, reproductive mode as primary driver between species. We also estimate past macroevolutionary shifts direction/intensity through shark phylogeny. were unable to find evidence significant early sharks hypothesise derived state clade, has evolved independently observed other vertebrates. Moreover, no relationship testes mass or oceanic depth sharks. However, support previous speculation an important determinant interspecific This vertebrates thought be trends, with role clades being inconsistent at best. phylogenetic distribution among superficially similar vertebrate clades, relative importance selective pressures underlying its evolution appears differ.

Language: Английский

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Sequential trait evolution did not drive deep-time diversification in sharks

Evolution, Journal Year: 2024, Volume and Issue: 78(8), P. 1405 - 1425

Published: May 15, 2024

Estimating how traits evolved and impacted diversification across the tree of life represents a critical topic in ecology evolution. Although there has been considerable research comparative biology, large parts remain underexplored. Sharks are an iconic clade marine vertebrates, key components ecosystems since early Mesozoic. However, few studies have addressed or whether they their extant diversity patterns. Our study aimed to fill this gap by reconstructing largest time-calibrated species-level phylogeny sharks compiling exhaustive database for ecological (diet, habitat) biological (reproduction, maximum body length) traits. Using state-of-the-art models evolution diversification, we outlined major character shifts modes trait shark species. We found support sequential estimated small medium-sized lecithotrophic coastal-dwelling most recent common ancestor sharks. our hidden analyses do not trait-dependent any examined traits, challenging previous works. This suggests that role shaping sharks' dynamics might previously overestimated should motivate future macroevolutionary investigate other drivers clade.

Language: Английский

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The ancestor of sharks and rays laid eggs, but ancestral state reconstructions need empirically supported traits and transparent reporting: a comment on Katona et al. (2023)

Journal of Evolutionary Biology, Journal Year: 2025, Volume and Issue: unknown

Published: March 29, 2025

Language: Английский

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A Global Synthesis of Population Demographic Models in Sharks and Rays

Fish and Fisheries, Journal Year: 2025, Volume and Issue: unknown

Published: April 15, 2025

ABSTRACT Demographic models are vital tools in fisheries management, particularly for data‐limited species such as sharks and rays. However, a significant gap exists the statistical quantification of productivity metrics related to elasmobranchs. This study addresses this by conducting meta‐analysis population rays, framed within scientometric context. We reviewed 91 publications, which revealed modest positive trend research over time. Our findings suggest that geographical distribution life history traits may be more important than ecological variables determining elasmobranch vulnerability fishing. Furthermore, Rays oviparous elasmobranchs generally exhibit higher finite rates growth ( λ ) compared viviparous elasmobranchs, respectively. when correcting phylogenetic relationships, these differences become statistically non‐significant, highlighting importance accounting non‐independence interpreting interspecific trends demographic traits. A negative correlation between mean lambda values IUCN status was found, indicating at greater risk extinction have lower values. Odontaspididae Mobulidae identified most vulnerable shark ray families fishing pressure, results inhabiting latitudes warmer temperatures pressure. Methodological approaches evolved, with notable increase use matrix Most studied demographically classified least concern, highlights need intensified efforts focused on threatened species, well addressing geographic biases prevalent developing countries.

Language: Английский

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The adaptability of facultative parthenogenesis and ‘multiple embryos per eggcase’ as alternative reproductive strategies in Chondrichthyes

Royal Society Open Science, Journal Year: 2025, Volume and Issue: 12(4)

Published: April 1, 2025

Chondrichthyans (sharks, rays and chimaera) are a fascinating case study through which to examine reproductive biology. While most vertebrate lineages have converged upon either placental viviparity or oviparity, chondrichthyans exhibit unparalleled diversity in mode other aspects of Despite this, our understanding variation this clade remains incomplete. Namely, several 'unusual' traits been repeatedly observed some chondrichthyan taxa, but we little no their adaptive value. Here, I focus on two (facultative parthenogenesis the deposition multiple embryos with separate yolks within single eggcase (MEPE)), theoretically result exponential increases fecundity. discuss theoretical fitness consequences these traits, range species eco-evolutionary contexts they documented major open questions regarding prevalence evolutionary consequences. It appears likely that both facultative MEPE at least taxa ecological contexts. However, additional data needed determine true effect lifetime fecundity, frequency occur, potential population-level effects cues triggers might favour switches from 'typical' sexual reproduction MEPE.

Language: Английский

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The sensory shark: high-quality morphological, genomic and transcriptomic data for the small-spotted catsharkScyliorhinus caniculareveal the molecular bases of sensory organ evolution in jawed vertebrates

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: May 24, 2024

Abstract Cartilaginous fishes (chimaeras and elasmobranchs -sharks, skates rays) hold a key phylogenetic position to explore the origin diversifications of jawed vertebrates. Here, we report integrate reference genomic, transcriptomic morphological data in small-spotted catshark Scyliorhinus canicula shed light on evolution sensory organs. We first characterise general aspects genome, confirming high conservation genome organisation across cartilaginous fishes, investigate population genomic signatures. Taking advantage dense sampling data, also identify gene signatures for all major organs, including chondrichthyan specializations, evaluate expression between paralogs within families involved functions. Finally, combine these with 3D synchrotron imaging situ analyses chondrichthyan-specific traits more evolutionary trends systems. This approach brings light, among others, novel markers ampullae Lorenzini electro-sensory cells, duplication hotspot crystallin genes conserved vertebrates, new metazoan clade Transient-receptor potential (TRP) family. These resources results, obtained an experimentally tractable model, open avenues multiomics study

Language: Английский

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The sensory shark: high-quality morphological, genomic and transcriptomic data for the small-spotted catshark Scyliorhinus canicula reveal the molecular bases of sensory organ evolution in jawed vertebrates

Molecular Biology and Evolution, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 6, 2024

Abstract Cartilaginous fishes (chondrichthyans: chimaeras and elasmobranchs -sharks, skates rays) hold a key phylogenetic position to explore the origin diversifications of jawed vertebrates. Here, we report integrate reference genomic, transcriptomic morphological data in small-spotted catshark Scyliorhinus canicula shed light on evolution sensory organs. We first characterise general aspects genome, confirming high conservation genome organisation across cartilaginous fishes, investigate population genomic signatures. Taking advantage dense sampling data, also identify gene signatures for all major organs, including chondrichthyan specializations, evaluate expression between paralogs within families involved functions. Finally, combine these with 3D synchrotron imaging situ analyses chondrichthyan-specific traits more evolutionary trends systems. This approach brings light, among others, novel markers ampullae Lorenzini electro-sensory cells, duplication hotspot crystallin genes conserved vertebrates, new metazoan clade transient-receptor potential (TRP) family. These resources results, obtained an experimentally tractable model, open avenues multiomics study

Language: Английский

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Functional characterization of follicle-stimulating hormone and luteinizing hormone receptors in cloudy catshark, Scyliorhinus torazame

General and Comparative Endocrinology, Journal Year: 2024, Volume and Issue: 354, P. 114542 - 114542

Published: April 27, 2024

The follicle-stimulating hormone receptor (FSHR) and luteinizing (LHR) in cloudy catshark were cloned, recombinant FSHR LHR expressed for characterization. Ventral lobe extract (VLE) from the pituitary contains homologous FSH LH, it stimulated cAMP signaling of dose-dependently. Two transcript variants (LHR-L with exon 10 LHR-S without) identified, was dominant form higher basal activity without VLE stimulation. Among various developmental stages follicles, expression mainly associated pre-vitellogenic early white follicles. When follicles recruited into vitellogenesis, decreased while upregulated reciprocally, suggesting that may also be responsible control vitellogenesis chondrichthyans. LHR-L among maturing before ovulation, indicating could have a specific role receiving LH surge signal final maturation. Plasma LH-like transiently increased prior to progesterone (P4)-surge testosterone-drop at beginning P4-phase, supporting follicle-maturation via follicular downregulated during P4-phase when high, LH-dependent downregulation is conserved chondrichthyans as other vertebrate lineages. (213 words).

Language: Английский

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