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1.
Braz J Biol ; 83: e275678, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38126637

RESUMO

The objective of this study was to evaluate reproductive traits in adults of Astyanax lacustris subjected to different spawning inducers. The study involved 240 females (12.54 g ± 2.33 and 7.66 cm ± 0.63 cm) and 240 males (5.83 g ± 0.39 g and 6.14 cm ± 0.64 cm), all at reproductive age. Three different inducers were evaluated: (i) 0.4 pellets of Ovopel®/kg of body weight; (ii) 0.5 ml of buserelin acetate/kg of body weight; and (iii) carp pituitary extract (CPE) (5.5 mg CPE/kg body weight for females and 2.5 mg CPE/kg body weight for males), as well as saline solution (without hormone). The degree-hours for spawning were greater (P<0.05) for the Ovopel® treatment (with 204.93) than in the treatment with CPE (183.2). Ovary weight and gonadosomatic index were higher (P<0.05) in CPE and Ovopel® treatments when compared to buserelin acetate. The number of oocytes per female, absolute and relative fecundity were greater (P<0.05) for Ovopel® and CPE treatments. Fertilization rate was higher (P<0.05) in treatment with buserelin acetate (82.3%) in relation to Ovopel® (72.33%) and CPE (62.40%) treatments, and the highest (P<0.05) hatching rates were achieved with buserelin acetate and Ovopel®. The number of larvae per female body weight was greater (P<0.05) when Ovopel® was used. In conclusion, Ovopel® proves to be a more effective reproductive inducer for induced reproduction of A. lacustris when compared to CPE and buserelin acetate.


Assuntos
Carpas , Characidae , Masculino , Animais , Feminino , Busserrelina/farmacologia , Reprodução , Peso Corporal
2.
Braz J Biol ; 83: e273525, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37909556

RESUMO

The Baixada Maranhense Environmental Protection Area of the Brazilian state of Maranhão encompasses a biologically rich region that includes the basins of four principal rivers, the Mearim, Pericumã, Pindaré, and Turiaçu, which form a complex of wetlands. The present study provides a comprehensive inventory of the fish fauna of the rivers that drain the Baixada Maranhense based on the identification of voucher specimens that were deposited in a scientific collection. Expeditions were conducted between 2014 and 2020. The inventory identified a total of 100 fish species representing 79 genera, 34 families, and 11 orders, which are found in both freshwater and estuarine environments. Six (Potamotrygon orbignyi, Leporinus piau, Moenkhausia loweae, Serrasalmus spilopleura, Pachypops fourcroi and Peckoltia greedoi) of the 100 taxa identified here are considered to be new records for one or more of the basins surveyed during this study, based on the existing data, while four - Colossoma macropomum, Megaleporinus macrocephalus, Cichla sp. and Cichla kelberi - are not native. The most speciose orders were the Siluriformes and Characiformes, while the most diverse families were the Loricariidae, Characidae, Auchenipteridae, Cichlidae, and Serrasalmidae. These data are consistent with the findings of most of the previous studies of freshwater ecosystems in the Neotropical region, in particular those of the rivers of Maranhão. The results of the present study represent an important advance in the understanding of the diversity of the fish fauna of the Mearim, Pericumã, Pindaré, and Turiaçu rivers, which are still poorly studied, and have likely had their diversity underestimated up to now.


Assuntos
Peixes-Gato , Characidae , Caraciformes , Ciclídeos , Humanos , Animais , Brasil , Ecossistema , Rios
3.
BMC Biol ; 21(1): 219, 2023 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-37840141

RESUMO

BACKGROUND: Social affinity and collective behavior are nearly ubiquitous in the animal kingdom, but many lineages feature evolutionarily asocial species. These solitary species may have evolved to conserve energy in food-sparse environments. However, the mechanism by which metabolic shifts regulate social affinity is not well investigated. RESULTS: In this study, we used the Mexican tetra (Astyanax mexicanus), which features riverine sighted surface (surface fish) and cave-dwelling populations (cavefish), to address the impact of metabolic shifts on asociality and other cave-associated behaviors in cavefish, including repetitive turning, sleeplessness, swimming longer distances, and enhanced foraging behavior. After 1 month of ketosis-inducing ketogenic diet feeding, asocial cavefish exhibited significantly higher social affinity, whereas social affinity regressed in cavefish fed the standard diet. The ketogenic diet also reduced repetitive turning and swimming in cavefish. No major behavioral shifts were found regarding sleeplessness and foraging behavior, suggesting that other evolved behaviors are not largely regulated by ketosis. We further examined the effects of the ketogenic diet via supplementation with exogenous ketone bodies, revealing that ketone bodies are pivotal molecules positively associated with social affinity. CONCLUSIONS: Our study indicated that fish that evolved to be asocial remain capable of exhibiting social affinity under ketosis, possibly linking the seasonal food availability and sociality.


Assuntos
Characidae , Cetose , Distúrbios do Início e da Manutenção do Sono , Animais , Characidae/fisiologia , Corpos Cetônicos , Evolução Biológica , Cavernas
4.
PLoS One ; 18(8): e0289574, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37535576

RESUMO

Complex patterns of acoustic communication exist throughout the animal kingdom, including underwater. The river-dwelling and the Pachón cave-adapted morphotypes of the fish Astyanax mexicanus are soniferous and share a repertoire of sounds. Their function and significance is mostly unknown. Here, we explored whether and how sounds produced by blind cavefishes inhabiting different Mexican caves may vary. We compared "Clicks" and "Serial Clicks" produced by cavefish in six different caves distributed in three mountain ranges in Mexico. We also sampled laboratory-bred cavefish lines originating from four of these caves. Sounds were extracted and analyzed using both a manual method and a machine learning-based automation tool developed in-house. Multi-parametric analyses suggest wild cave-specific acoustic signatures, or "accents". An acoustic code also existed in laboratory cavefish lines, suggesting a genetic basis for the evolution of this trait. The variations in acoustic parameters between caves of origin did not seem related to fish phenotypes, phylogeography or ecological conditions. We propose that the evolution of such acoustic signatures would progressively lead to the differentiation of local accents that may prevent interbreeding and thus contribute to speciation.


Assuntos
Cavernas , Characidae , Animais , México , Characidae/genética , Filogeografia , Acústica , Evolução Biológica
5.
J Fish Biol ; 103(5): 1122-1128, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37562847

RESUMO

A new species, Moenkhausia iris, is described from the upper rio Madeira basin, Mato Grosso State, Brazil. The new species is unique among congeners by its color in life, which is the dorsal half of body blue or green and ventral half red, more intense above the anal fin. Additionally, it can be distinguished by having a single, vertically elongated humeral spot, a lateral surface of body, caudal peduncle, and anal fin without distinct blotches or oblique marks and 18-19 branched anal-fin rays. The new species is endemic from a small tributary of the Rio Guaporé, rio Madeira drainage at Chapada dos Parecis. Its putatively close relatives are endemic to the upper rio Juruena located at the same shield. Both headwaters are very close to each other, sharing other restricted range species, and their hydrogeological topography indicates the upper rio Juruena stretch was captured by the rio Guaporé through a headwater capture event. Moenkhausia iris is much appreciated in the international aquarium trade, as well as many other tetras endemic from the same area. Exportation is based on the capture of wild individuals so sustainable exploitation is necessary for its conservation.


Assuntos
Characidae , Caraciformes , Humanos , Animais , Brasil , Rios
6.
Aquat Toxicol ; 262: 106637, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37572499

RESUMO

Aluminum is a metal widely used from household utensils to civil construction. Anodizing aluminum is a procedure to form a thick layer of aluminum oxide on the surface in order to confer greater resistance to the material. This process generates an effluent with acidic pH and a high concentration of sulfate. Alternatives for the treatment of this effluent involve the use of the chemical precipitation technique, which can be used with salts of barium chloride (BaCl2), calcium chloride (CaCl2), and aluminum hydroxide with commercial limestone (Cc/Al (OH)3). The objective of this study was to evaluate the toxicity of effluents on Astyanax altiparanae (Lambari), by means of somatic, genetic, morphological, and histological markers after 24 and 96 h of exposure. After measuring the biometric data of the animals and the weight of the liver, we found that the condition factor (K) of individuals exposed to the effluent CaCl2 showed a slight reduction in growth after 96 h while the hepatosomatic index (HSI) remained unchanged for all effluents in both sampling times. The micronucleus test with erythrocytes indicated that the raw effluent (E2) induced nuclear changes after 24 h; however, this effect did not persist after 96 h of exposure. Branchial arches were collected and according to Bernet's index for histopathology, all effluents except Cc/Al (OH)3, induced significant changes in the gills. In accordance with the index of Poleksic and Mitrovic-Tutundzic, CaCl2 was the only effluent to compromise branchial operation. The branchial morphology investigated by SEM showed that the raw effluent (E1) induced injuries and compromised gill functions. This study reinforces the importance of biological tests for the assessment and validation of physical chemicals used and effluent treatment techniques as well as the development and application of biological parameters before the wastewater release, whether in a raw state or a treated one.


Assuntos
Characidae , Poluentes Químicos da Água , Animais , Alumínio/toxicidade , Poluentes Químicos da Água/toxicidade , Cloreto de Cálcio , Metais
7.
Zool Res ; 44(4): 750-760, 2023 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-37464932

RESUMO

Feeding strategies of an organism depend on the multimodal sensory processing that most efficiently integrates available visual, chemosensory, and/or mechanoreceptive cues as part of their environmental adaptation. The blind cavefish morph of Astyanax mexicanus has developed sensory-dependent behaviors to find food more efficiently than their eyed, surface-morph counterparts while in darkness. In the absence of light, adult cavefish have evolved enhanced behaviors, such as vibration attraction behavior (VAB), and changes in feeding angle. Here, we identified evolved differences in cavefish larval prey capture (LPC) behavior. In the dark, LPC is more efficient in cavefish than in surface fish. Furthermore, different cave populations express laterality in their LPC and strike towards prey preferentially located on their left or right sides. This suggests the occurrence, to some extent, of divergent LPC evolution among cave populations. While LPC can be triggered exclusively by a vibration stimulus in both surface and cavefish, we provide evidence that LPC is, at least partially, a multimodal sensory process different from adult VAB. We also found that a lack of food may exacerbate the laterality of LPC. Thus, we proposed a mathematical model for explaining laterality based on a balance between: (1) enlarged range of foraging field (behavioral or perceptive) due to asymmetry, (2) food abundance, and (3) disadvantages caused by laterality (unequal lateral hydrodynamic resistance when swimming, allocation of resources for the brain and receptors, and predator escape).


Assuntos
Characidae , Animais , Larva , Comportamento Animal , Evolução Biológica , Cavernas
8.
Zool Res ; 44(4): 761-775, 2023 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-37464933

RESUMO

Cave-adapted animals provide a unique opportunity to study the evolutionary mechanisms underlying phenotypic, metabolic, behavioral, and genetic evolution in response to cave environments. The Mexican tetra ( Astyanax mexicanus) is considered a unique model system as it shows both surface and cave-dwelling morphs. To date, at least 33 different cave populations have been identified, with phylogenetic studies suggesting an origin from at least two independent surface lineages, thereby providing a unique opportunity to study parallel evolution. In the present study, we carried out the most exhaustive phylogeographic study of A. mexicanus to date, including cave and surface localities, using two mitochondrial markers (cytochrome b (cyt b) and cytochrome c oxidase subunit I ( COI)) and nuclear rhodopsin visual pigment ( rho). Additionally, we inferred the molecular evolution of rho within the two contrasting environments (cave and surface) and across three geographic regions (Sierra de El Abra, Sierra de Guatemala, and Micos). In total, 267 individuals were sequenced for the two mitochondrial fragments and 268 individuals were sequenced for the rho visual pigment from 22 cave and 46 surface populations. Phylogeographic results based on the mitochondrial data supported the two-lineage hypothesis, except for the Pachón and Chica caves, whose introgression has been largely documented. The Sierra de El Abra region depicted the largest genetic diversity, followed by the Sierra de Guatemala region. Regarding the phylogeographic patterns of rho, we recovered exclusive haplogroups for the Sierra de El Abra (Haplogroup I) and Sierra de Guatemala regions (Haplogroup IV). Moreover, a 544 bp deletion in the rho gene was observed in the Escondido cave population from Sierra de Guatemala, reducing the protein from seven to three intramembrane domains. This change may produce a loss-of-function (LOF) but requires further investigation. Regarding nonsynonymous ( dN) and synonymous ( dS) substitution rates (omega values ω), our results revealed the prevailing influence of purifying selection upon the rho pigment for both cave and surface populations (ω<1), but relaxation at the El Abra region. Notably, in contrast to the other two regions, we observed an increase in the number of dN mutations for Sierra de El Abra. However, given that a LOF was exclusively identified in the Sierra de Guatemala region, we cannot dismiss the possibility of a pleiotropic effect on the Rho protein.


Assuntos
Characidae , Rodopsina , Animais , Filogeografia , Filogenia , Rodopsina/genética , Characidae/genética , Evolução Molecular
9.
Zool Res ; 44(4): 782-792, 2023 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-37464936

RESUMO

Astyanax mexicanus has repeatedly colonized cave environments, displaying evolutionary parallelisms in many troglobitic traits. Despite being a model system for the study of adaptation to life in perpetual darkness, the parasites that infect cavefish are practically unknown. In this study, we investigated the macroparasite communities in 18 cavefish populations from independent lineages and compared them with the parasite diversity found in their sister surface fish populations, with the aim of better understanding the role that parasites play in the colonization of new environments. Within the cavefish populations, we identified 13 parasite taxa, including a subset of 10 of the 27 parasite taxa known for the surface populations. Parasites infecting the cavefish belong to five taxonomic groups, including trematodes, monogeneans, nematodes, copepods, and acari. Monogeneans are the most dominant group, found in 14 caves. The macroparasites include species with direct life cycles and trophic transmission, including invasive species. Surprisingly, paired comparisons indicate higher parasite richness in the cavefish than in the surface fish. Spatial variation in parasite composition across the caves suggests historical and geographical contingencies in the host-parasite colonization process and potential evolution of local adaptations. This base-line data on parasite diversity in cavefish populations of A. mexicanus provides a foundation to explore the role of divergent parasite infections under contrasting ecological pressures (cave vs. surface environments) in the evolution of cave adaptive traits.


Assuntos
Characidae , Interações Hospedeiro-Parasita , Animais , Escuridão , Adaptação Fisiológica , Cavernas , Evolução Biológica
10.
Zool Res ; 44(4): 808-820, 2023 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-37464938

RESUMO

Recent colonization of extreme environments provides unique opportunities to study the early steps of adaptation and the potential for rapid convergent evolution. However, phenotypic shifts during recent colonization may also be due to plasticity in response to changes in the rearing environment. Here, we analyzed a suite of morphological and behavioral traits in paired surface, subterranean, and facultatively subterranean Mexican tetras ( Astyanax mexicanus) from recent introductions in two separate watersheds outside of their native range. We found a variety of phenotypic and behavioral shifts between subterranean and surface populations that are similar to those observed in relatively ancient populations in Mexico. Despite this rapid morphological divergence, we found that most of these trait differences were due to plasticity in response to rearing environments. While most trait assays in common-garden, lab-raised fish indicated that phenotypic shifts in wild fish were the result of plasticity, we also found evidence of genetic control in several traits present in subterranean populations. Interestingly, wall-following behavior, an important subterranean foraging behavior, was greater in lab-born subterranean fish than in lab-born surface fish, suggesting rapid divergence of this trait between subterranean and surface populations. Thus, this study sheds light on the early steps of subterranean evolution, identifies potential rapid behavioral evolution, and suggests that plasticity in traits involving exploratory behavior may facilitate subterranean colonization.


Assuntos
Evolução Biológica , Characidae , Animais , Characidae/genética , Ecossistema , Fenótipo , Cavernas
11.
J Exp Zool A Ecol Integr Physiol ; 339(9): 861-868, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37493010

RESUMO

Proper muscle function and muscle fiber structures that match the environmental demands of organisms are imperative to their success in any ecosystem. The Mexican cavefish, Astyanax mexicanus, has two morphotypes: an obligate cave-dwelling form that lives in thermally insulated caves and an O2 poor environment, and a surface form that lives in a more thermally variable, but O2 rich river environment. As environment can determine physiological adaptations, it is of interest to compare the aerobic and anaerobic metabolic profiles of white muscle metabolism in both morphotypes of this species, as well as their muscle structures. Here, we used white muscle of both morphotypes of the Mexican cavefish to determine citrate synthase (CS) activity as a measure of aerobic potential, and lactate concentration as a measure of anaerobic potential at three different chronic acclimation temperatures (14°C, 25°C, and 31°C). By examining aerobic and anaerobic potential in both morphs, we sought to link environmental thermal flexibility to muscle metabolism. We found that the surface morphotype had higher CS activity and lower lactate concentration, suggesting an overall more efficient usage of aerobic metabolism; whereas the cave morphotype showed lower CS activity and higher lactate concentration, suggesting a stronger reliance on anaerobic pathways. We also measured white muscle histological variables that have been previously linked to whole-animal metabolism: fiber diameter, number of nuclei per mm of fiber and myonuclear domain (MND) of both morphotypes at 25°C to examine cell-level differences in muscle morphology. However, we found no differences in fiber diameter, number of nuclei per mm of fiber or MND between the two morphotypes. Thus, although the cellular morphology is similar in these species, the environmental differences in the evolution of the two morphs has led to differences in their metabolic profiles.


Assuntos
Cavernas , Characidae , Animais , Ecossistema , Anaerobiose , Fibras Musculares Esqueléticas , Lactatos
12.
Elife ; 122023 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-37498318

RESUMO

The vertebrate brain is highly conserved topologically, but less is known about neuroanatomical variation between individual brain regions. Neuroanatomical variation at the regional level is hypothesized to provide functional expansion, building upon ancestral anatomy needed for basic functions. Classically, animal models used to study evolution have lacked tools for detailed anatomical analysis that are widely used in zebrafish and mice, presenting a barrier to studying brain evolution at fine scales. In this study, we sought to investigate the evolution of brain anatomy using a single species of fish consisting of divergent surface and cave morphs, that permits functional genetic testing of regional volume and shape across the entire brain. We generated a high-resolution brain atlas for the blind Mexican cavefish Astyanax mexicanus and coupled the atlas with automated computational tools to directly assess variability in brain region shape and volume across all populations. We measured the volume and shape of every grossly defined neuroanatomical region of the brain and assessed correlations between anatomical regions in surface fish, cavefish, and surface × cave F2 hybrids, whose phenotypes span the range of surface to cave. We find that dorsal regions of the brain are contracted, while ventral regions have expanded, with F2 hybrid data providing support for developmental constraint along the dorsal-ventral axis. Furthermore, these dorsal-ventral relationships in anatomical variation show similar patterns for both volume and shape, suggesting that the anatomical evolution captured by these two parameters could be driven by similar developmental mechanisms. Together, these data demonstrate that A. mexicanus is a powerful system for functionally determining basic principles of brain evolution and will permit testing how genes influence early patterning events to drive brain-wide anatomical evolution.


Assuntos
Evolução Biológica , Characidae , Animais , Camundongos , Peixe-Zebra , Characidae/genética , Encéfalo , Fenótipo
13.
Annu Rev Cell Dev Biol ; 39: 23-44, 2023 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-37437210

RESUMO

Our understanding of cell and developmental biology has been greatly aided by a focus on a small number of model organisms. However, we are now in an era where techniques to investigate gene function can be applied across phyla, allowing scientists to explore the diversity and flexibility of developmental mechanisms and gain a deeper understanding of life. Researchers comparing the eyeless cave-adapted Mexican tetra, Astyanax mexicanus, with its river-dwelling counterpart are revealing how the development of the eyes, pigment, brain, cranium, blood, and digestive system evolves as animals adapt to new environments. Breakthroughs in our understanding of the genetic and developmental basis of regressive and constructive trait evolution have come from A. mexicanus research. They include understanding the types of mutations that alter traits, which cellular and developmental processes they affect, and how they lead to pleiotropy. We review recent progress in the field and highlight areas for future investigations that include evolution of sex differentiation, neural crest development, and metabolic regulation of embryogenesis.


Assuntos
Evolução Biológica , Characidae , Animais , Characidae/genética , Modelos Biológicos , Encéfalo , Biologia do Desenvolvimento
14.
Environ Pollut ; 334: 122152, 2023 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-37414119

RESUMO

Ethiprole, a phenylpyrazole insecticide, has been increasingly used in the Neotropical region to control stink bug pests in soybean and maize fields. However, such abrupt increases in use may have unintended effects on non-target organisms, including those inhabiting freshwater ecosystems. Here, we evaluated the effects of acute (96 h) sublethal exposure to ethiprole (up to 180 µg/L, which is equivalent to 0.013% of the recommended field dose) on biomarkers of stress in the gills, liver, and muscle of the Neotropical fish Astyanax altiparanae. We further recorded potential ethiprole-induced effects on the structural histology of A. altiparanae gills and liver. Our results showed that ethiprole exposure increased glucose and cortisol levels in a concentration-dependent manner. Ethiprole-exposed fish also exhibited higher levels of malondialdehyde and greater activity of antioxidant enzymes, such as glutathione-S-transferase and catalase, in both gills and liver. Furthermore, ethiprole exposure led to increased catalase activity and carbonylated protein levels in muscle. Morphometric and pathological analyses of the gills revealed that increasing ethiprole concentration resulted in hyperemia and loss of integrity of the secondary lamellae. Similarly, histopathological analysis of the liver demonstrated higher prevalence of necrosis and inflammatory infiltrates with increasing ethiprole concentration. Altogether, our findings demonstrated that sublethal exposure to ethiprole can trigger a stress response in non-target fish species, which may lead to potential ecological and economic imbalances in Neotropical freshwater systems.


Assuntos
Characidae , Poluentes Químicos da Água , Animais , Catalase/metabolismo , Ecossistema , Estresse Oxidativo , Poluentes Químicos da Água/metabolismo , Antioxidantes/metabolismo , Glutationa Transferase/metabolismo , Fígado/metabolismo , Brânquias/metabolismo , Peroxidação de Lipídeos
15.
Sci Rep ; 13(1): 12051, 2023 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-37491348

RESUMO

Astyanax mexicanus is a well-known model species, that has two morphotypes, cavefish, from subterranean rivers and surface fish, from surface rivers. They are morphologically distinct due to many troglomorphic traits in the cavefish, such as the absence of eyes. Most studies on A. mexicanus are focused on eye development and protein-coding genes involved in the process. However, lncRNAs did not get the same attention and very little is known about them. This study aimed to fill this knowledge gap, identifying, describing, classifying, and annotating lncRNAs expressed in the embryo's eye tissue of cavefish and surface fish. To do so, we constructed a concise workflow to assemble and evaluate transcriptomes, annotate protein-coding genes, ncRNAs families, predict the coding potential, identify putative lncRNAs, map them and predict interactions. This approach resulted in the identification of 33,069 and 19,493 putative lncRNAs respectively mapped in cavefish and surface fish. Thousands of these lncRNAs were annotated and identified as conserved in human and several species of fish. Hundreds of them were validated in silico, through ESTs. We identified lncRNAs associated with genes related to eye development. This is the case of a few lncRNAs associated with sox2, which we suggest being isomorphs of the SOX2-OT, a lncRNA that can regulate the expression of sox2. This work is one of the first studies to focus on the description of lncRNAs in A. mexicanus, highlighting several lncRNA targets and opening an important precedent for future studies focusing on lncRNAs expressed in A. mexicanus.


Assuntos
Characidae , RNA Longo não Codificante , Humanos , Animais , Characidae/genética , RNA Longo não Codificante/genética , Olho , Evolução Biológica , Cavernas
16.
PeerJ ; 11: e15117, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37309369

RESUMO

The Neotropics contain one of the most diverse assemblages of freshwater fishes worldwide. Part of this diversity is shared between the Orinoco and Amazon basins. These basins have been separated for a long time due to the Vaupes Arch, rising between 10-11 Ma. Today, there is only one permanent connection between the Orinoco and Negro (Amazon) basins, known as the Casiquiare Canal. However, alternative corridors allowing fish dispersion between both basins have been proposed. The cardinal tetra (Paracheirodon axelrodi), the most important fish in the ornamental world market, is distributed in both basins. Here we investigated P. axelrodi phylogeography, population structure, and potential routes of migration and connectivity between the two basins. A total of 468 bp of the mitochondrial gene (COI), 555 bp of the nuclear gene fragment (MYH6), and eight microsatellite loci were analyzed. As a result, we found two major genetic clusters as the most likely scenario (K = 2), but they were not discreetly distributed between basins. A gradient of genetic admixture was observed in Cucui and São Gabriel da Cachoeira, between the upper Negro River and the upper Orinoco. Samples from the middle-lower Negro River were highly structured. Cucui (Negro basin) was more similar to the Orinoco than to the rest of the Negro basin populations. However, substructure was also observed by the discriminant analysis, fixation indices and other hierarchichal structure analyses (K = 3 - 6), showing three major geographic clusters: Orinoco, Cucui, and the remaining Negro basin. Unidirectional migration patterns were detected between basins: via Cucui toward Orinoco and via the remaining of the Negro basin toward Orinoco. Results from the Relaxed Random Walk analysis support a very recent origin of this species in the headwater Orinoco basin (Western Guiana Shield, at late Pleistocene) with a later rapid colonization of the remaining Orinoco basin and almost simultaneously the Negro River via Cucui, between 0.115 until about 0.001 Ma. Historical biogeography and population genetic patterns observed here for Cardinal tetra, seem to be better explained by river capture, physical, or ecological barriers than due to the geographic distance.


Assuntos
Characidae , Rios , Animais , Água Doce , Filogeografia
17.
J Toxicol Environ Health A ; 86(14): 459-478, 2023 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-37313572

RESUMO

Herbicides are used in agriculture to control harmful crop weeds, prevent algae proliferation, and enhance macrophyte growth. Herbicide contamination of water bodies might exert toxic effects on fish in different development stages. Sperm, embryos, and adults of Astyanax altiparanae were used as a model to examine the detrimental effects of the following herbicide formulations: Roundup Transorb® (glyphosate), Arsenal® NA (imazapyr), and Reglone® (diquat). The lethal concentration 50 (LC50) values for adults using glyphosate and imazapyr were 3.14 mg/L and 4.59 mg/L, respectively, while the LC50 was higher than 28 mg/L for diquat. For the initial stages of embryo development, LC50 values were 16.52 mg/L glyphosate, 9.33 mg/L imazapyr, and 1084 mg/L diquat. Inhibition of sperm motility was noted at 252 mg/L glyphosate, 137 mg/L imazapyr, and 11,300 mg/L diquat, with an average sperm viability of 12.5%, 73.2%, and 89.3%, respectively, compared to 87.5% detected to control. A. altiparanae exhibited different sensitivities to the herbicide formulations investigated in the developmental stages evaluated. Roundup Transorb® exposure was more toxic for adults, while Arsenal® NA was most harmful for early embryonic development and inhibited sperm motility. Reglone® demonstrated low toxicity for A. altiparanae compared to Roundup Transorb® and Arsenal® NA. A. altiparanae may be considered an emerging fish model for toxicological studies for the neotropical region due to its wide distribution and biological characteristics.


Assuntos
Characidae , Caraciformes , Herbicidas , Poluentes Químicos da Água , Animais , Masculino , Herbicidas/toxicidade , Diquat , Motilidade dos Espermatozoides , Sêmen , Poluentes Químicos da Água/toxicidade
18.
J Fish Biol ; 103(1): 136-142, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37177854

RESUMO

A new species of Knodus from the Rio Cupari, a right-bank tributary of the lower Rio Tapajós, is described. Among its congeners, the new species shares exclusively with K. figueiredoi the presence of only uni-tricuspid teeth in the premaxilla, maxilla and dentary. Knodus borari differs from K. figueiredoi by the colour pattern and morphological characteristics. The new species is the fifth species of the genus described from the Rio Tapajós basin, and the second restricted to the lower portion of the basin. This is additional evidence that the lower Rio Tapajós basin is a region of ichthyofaunal endemism.


Assuntos
Characidae , Caraciformes , Dente , Animais , Characidae/anatomia & histologia , Caraciformes/anatomia & histologia , Rios , Brasil
19.
Commun Biol ; 6(1): 585, 2023 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-37258699

RESUMO

We experimentally investigate the role of illumination on the collective dynamics of a large school (ca. 50 individuals) of Hemigrammus rhodostomus. The structure of the group, defined using two order parameters, is quantified while progressively altering the visual range of the fish through controlled cycles of ambient light intensity. We show that, at low light levels, the individuals within the group are unable to form a cohesive group, while at higher illuminance the degree of alignment of the school correlates with the light intensity. When increasing the illuminance, the school structure is successively characterized by a polarized state followed by a highly regular and stable rotational configuration (milling). Our study shows that vision is necessary to achieve cohesive collective motion for free swimming fish schools, while the short-range lateral line sensing is insufficient in this situation. The present experiment therefore provides new insights into the interaction mechanisms that govern the emergence and intensity of collective motion in biological systems.


Assuntos
Characidae , Comportamento Social , Animais , Comportamento Animal , Modelos Biológicos , Visão Ocular
20.
Nat Commun ; 14(1): 2557, 2023 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-37137902

RESUMO

Laboratory studies have demonstrated that a single phenotype can be produced by many different genotypes; however, in natural systems, it is frequently found that phenotypic convergence is due to parallel genetic changes. This suggests a substantial role for constraint and determinism in evolution and indicates that certain mutations are more likely to contribute to phenotypic evolution. Here we use whole genome resequencing in the Mexican tetra, Astyanax mexicanus, to investigate how selection has shaped the repeated evolution of both trait loss and enhancement across independent cavefish lineages. We show that selection on standing genetic variation and de novo mutations both contribute substantially to repeated adaptation. Our findings provide empirical support for the hypothesis that genes with larger mutational targets are more likely to be the substrate of repeated evolution and indicate that features of the cave environment may impact the rate at which mutations occur.


Assuntos
Characidae , Animais , Characidae/genética , Mutação , Fenótipo , Adaptação Fisiológica/genética , Genótipo , Evolução Biológica , Cavernas
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