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1.
Dis Aquat Organ ; 144: 133-142, 2021 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-33955851

RESUMO

Complex interactions among hosts, pathogens, and the environment affect the vulnerability of amphibians to the emergence of infectious diseases such as chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd). Boana curupi is a forest-dwelling amphibian endemic to the southern Atlantic Forest of South America, a severely fragmented region. Here, we evaluated whether abiotic factors (including air and water temperature, relative air humidity, and landscape) are correlated with chytrid infection intensity and prevalence in B. curupi. We found individuals infected with Bd in all populations sampled. Prevalence ranged from 25-86%, and the infection burden ranged from 1 to over 130000 zoospore genomic equivalents (g.e.) (mean ± SD: 4913 ± 18081 g.e.). The infection load differed among populations and was influenced by forest cover at scales of 100, 500, and 1000 m, with the highest infection rates recorded in areas with a higher proportion of forest cover. Our results suggest that the fungus is widely distributed in the populations of B. curupi in southern Brazil. Population and disease monitoring are necessary to better understand the relationships between host, pathogen, and environment, especially when, as in the case of B. curupi, threatened species are involved.


Assuntos
Quitridiomicetos , Micoses , Anfíbios , Animais , Anuros , Brasil/epidemiologia , Florestas , Micoses/epidemiologia , Micoses/veterinária
2.
Arch Environ Contam Toxicol ; 80(4): 789-800, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33876257

RESUMO

Insecticides are important in agriculture, to reduce human disease, and to decrease the nuisance of biting insects. Despite this, many have the potential for environmental impacts and toxicity in nontarget organisms. We reviewed data on the effects of insecticides based on toxins from Bacillus thuringiensis var. israelensis (Bti) and Bacillus thuringiensis var. kurstaki (Btk) on amphibians. The few peer-reviewed publications that are available for Bti provide variable conclusions, ranging from few observable effects to evidence of acute toxicity at high concentrations. We briefly highlight the current controversies and identify key areas for future investigation.


Assuntos
Bacillus thuringiensis , Anfíbios , Animais , Agentes de Controle Biológico/toxicidade , Humanos , Larva , Sorogrupo
3.
J Zoo Wildl Med ; 52(1): 90-96, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33827165

RESUMO

Population pharmacokinetics utilizing sparse sampling were used to determine pharmacokinetics of ceftazidime in eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) due to their slow growth rate and the limited number of appropriately sized individuals in the zoo-housed population. Twenty-five eastern hellbenders received a single subcutaneous injection of ceftazidime at 20 mg/kg. Each animal had blood samples collected up to four times between 0 and 192 hr postinjection. Plasma samples were analyzed by high-pressure liquid chromatography. A nonlinear mixed-effects model was fitted to the data to determine typical values for population parameters, an ideal method due to the sampling limitation of each hellbender. Results indicate an elimination half-life of 36.63 hr and volume of distribution of 0.31 L/kg. Antibiotic concentrations were above a minimum inhibitory concentration (MIC) value of 8 µg/ml for 120 hr. Prior to antibiotic administration, six hellbenders had oral and six other individuals had cloacal swabs taken for aerobic culture. Fifty-five bacterial isolates were obtained (24 cloacal, 31 oral) with 10/12 (83%) individuals growing three or more different isolates and 11/12 (92%) growing Shewanella putrefaciens. Twelve isolates had susceptibility testing performed and all were susceptible to ceftazidime. These results indicate that ceftazidime is an appropriate choice of antibiotic in hellbenders and when given at a dosage of 20 mg/kg subcutaneously, maintains concentrations above the MIC of susceptible bacteria for up to 5 days.


Assuntos
Anfíbios/metabolismo , Antibacterianos/farmacocinética , Ceftazidima/farmacocinética , Anfíbios/sangue , Animais , Antibacterianos/administração & dosagem , Antibacterianos/sangue , Área Sob a Curva , Ceftazidima/administração & dosagem , Ceftazidima/sangue , Cloaca/microbiologia , Meia-Vida , Injeções Subcutâneas , Boca/microbiologia , Projetos Piloto
4.
Dis Aquat Organ ; 144: 89-98, 2021 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-33830072

RESUMO

Amphibians are globally threatened by emerging infectious diseases, and ranaviruses are among the most concerning pathogens to threaten species in the wild. We sampled for ranaviruses in wild amphibians at 8 sites in Costa Rica, spanning broad climatic zones and taxonomic associations. Seven of these sites are inhabited by highly threatened amphibian species that persist at low global population sizes after population declines due to amphibian chytridiomycosis. One of the surveyed sites is occupied by an introduced amphibian species, which is relatively rare in Central America but may be an important pathway for long-distance transport of ranaviruses. We detected ranavirus using quantitative polymerase chain reaction in 16.3% of the 243 individuals and among 5 of our 8 sites, but not at the site with the introduced species. Infection prevalence varied among species and sites, but not with mean annual temperature or mean annual precipitation. Infection intensity did not vary with species, site, temperature, or precipitation. Our results show that ranavirus infection is spatially widespread in Costa Rica, affecting a broad range of host species, and occurs across climatic zones-though we encountered no mortality or morbidity in our sampled species. Ranaviruses are known to cause intermittent mass mortality in amphibian populations, and the threatened species sampled here are likely vulnerable to population impacts from emerging ranaviruses. Therefore, we believe the potential impacts of ranaviruses on amphibian populations in tropical regions have likely been underestimated, and that they should be viewed as a potential major stressor to threatened amphibians in tropical regions.


Assuntos
Infecções por Vírus de DNA , Ranavirus , Anfíbios , Animais , América Central , Costa Rica/epidemiologia , Infecções por Vírus de DNA/epidemiologia , Infecções por Vírus de DNA/veterinária
5.
Dis Aquat Organ ; 144: 99-106, 2021 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-33830073

RESUMO

Environmental variation along elevational gradients shapes conditions for pathogen development, which influences disease outcomes. Chytridiomycosis is a non-vectored disease caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd) and is responsible for massive declines of amphibian populations all over the world. Several biotic and abiotic factors are known to influence Bd infection dynamics in amphibians, including temperature and host species richness. Here, we quantified Bd prevalence and load along an elevational gradient in the Caparaó National Park (CNP), Brazil, and tested for associations of Bd infections with elevation, temperature, and species richness. We hypothesized that Bd infections would increase as local species richness decreased with elevation. We detected Bd along the entire elevational gradient and found a negative association between infection load and elevation. We did not detect significant associations between infection prevalence and elevation. Our findings are consistent with other wide elevational gradient studies, but are contrary to 2 other studies performed in the Atlantic Forest. We did not find the minimum elevational range that should be sampled to detect the influence of elevation on Bd variation. Our study represents the widest elevational gradient that has been sampled in Brazil and contributes to a better understanding of Bd distribution and dynamics in natural systems.


Assuntos
Quitridiomicetos , Micoses , Anfíbios , Animais , Brasil/epidemiologia , Florestas , Micoses/epidemiologia , Micoses/veterinária
6.
J Zoo Wildl Med ; 52(1): 373-378, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33827201

RESUMO

Thirteen wild-caught hellbenders (Cryptobranchus alleganiensis) were treated for Batrachochytrium dendrobatidis with continuous chloramphenicol baths at concentrations of 20 mg/L for 14 days and 200 mg/L for 14 days. Clinical signs and deaths continued after treatment with 20 mg/L chloramphenicol but ceased after treatment with 200 mg/L chloramphenicol. No evidence of toxicity was found on hematologic tests, necropsy, or histopathologic examination. Lower infection burdens were detected after treatment with chloramphenicol, but infection rates were unchanged. Chloramphenicol may be useful as a treatment for B. dendrobatidis in hellbenders but did not clear hellbenders of infection.


Assuntos
Anfíbios/microbiologia , Antibacterianos/uso terapêutico , Cloranfenicol/uso terapêutico , Micoses/veterinária , Animais , Micoses/tratamento farmacológico
7.
Sci Total Environ ; 770: 145382, 2021 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-33736409

RESUMO

The rise in sea-level and the increase in frequency and intensity of extreme weather events (i.e., storms and associated surges) are expected to strongly impact coastal areas. The gradual impacts of sea-level rise may allow species to display adaptive responses to overcome environmental changes. In contrast, the abruptness of marine submersions during extreme weather events can induce changes that may exceed the ability of species to respond to brutally changing environments. Yet, site-specific topographical features may buffer the expected detrimental effects of marine submersions on wildlife. In order to test such topographical effects, we examined the long-term consequences of a major marine submersion (storm Xynthia) on the amphibian communities of two French Atlantic coastal wetlands that slightly differ in their topography and, thus, their susceptibility to marine submersion. Amphibians were monitored on 64 ponds for up to 13 years, using acoustic and visual methods, in conjunction with environmental parameters (e.g., pond topology, vegetation, salinity). We found that the amphibian communities at the two neighboring sites displayed different responses to the marine submersion linked to storm Xynthia. As predicted, slight differences in local topography induced strong differences in local magnitude of the landward marine surge, influencing salinization dynamics and associated consequences on wildlife (amphibians). The different species responses show that amphibian richness can recover to that of pre-storm conditions, but with significant changes in the composition of the community. Our results suggest that amphibian presence post-submersion in coastal wetlands results from an interaction between species traits (e.g., tolerance to elevated salinity), site-specific topography, and environmental parameters. Finally, our study emphasizes that relatively modest landscaping management may be critical to allow wildlife to successfully recover after a marine submersion.


Assuntos
Imersão , Áreas Alagadas , Anfíbios , Animais , Salinidade , Elevação do Nível do Mar
8.
Environ Monit Assess ; 193(4): 216, 2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33759034

RESUMO

With amphibian populations facing a multitude of threats, including habitat loss, climate change, invasive species and infectious diseases, it is important to identify valuable amphibian habitat and the imminent pressures these environments face. Between 2004 and 2019, 6 years of amphibian surveys were conducted at Greenburn, Roe and McLean lakes in the Southern Gulf Islands of British Columbia, Canada. We assessed (1) species composition and trends of native amphibians, including at-risk northern red-legged frog (Rana aurora); (2) observations of invasive American bullfrog (Lithobates catesbeianus); and (3) the efficacy of visual encounter and trapping survey methods in determining multi-species amphibian occupancy. The shallow, semi-ephemeral McLean Lake hosted more amphibian species and more breeding activity than the larger, deeper waters of Greenburn and Roe lakes. Despite multiple observations, bullfrogs have thus far not established a detectable population within these lakes, with the presence of native and introduced predators as potential contributing factors. Declining trends in occupancy of native populations of R. aurora, Pacific chorus frog (Pseudacris regilla) and rough-skinned newt (Taricha granulosa) were observed at all three lakes. Results varied within years by species and survey method, highlighting the importance of effective replication and employing complementary survey methods to optimize studies of amphibian occupancy. These observations also emphasize the value of shallow, small- to medium-sized waterbodies to native amphibian populations in the Southern Gulf Islands. As these waterbodies become increasingly threatened by global climate change and habitat degradation, the potential impacts of declining freshwater ecosystem health on amphibian populations should be considered.


Assuntos
Ecossistema , Monitoramento Ambiental , Anfíbios , Animais , Colúmbia Britânica , Espécies Introduzidas , Dinâmica Populacional
9.
Nat Ecol Evol ; 5(4): 513-519, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33526889

RESUMO

Disturbance and habitat modification by humans can alter animal movement, leading to negative impacts on fitness, survival and population viability. However, the ubiquity and nature of these impacts across diverse taxa has not been quantified. We compiled 208 studies on 167 species from terrestrial and aquatic ecosystems across the globe to assess how human disturbance influences animal movement. We show that disturbance by humans has widespread impacts on the movements of birds, mammals, reptiles, amphibians, fish and arthropods. More than two-thirds of 719 cases represented a change in movement of 20% or more, with increases in movement averaging 70% and decreases -37%. Disturbance from human activities, such as recreation and hunting, had stronger impacts on animal movement than habitat modification, such as logging and agriculture. Our results point to a global restructuring of animal movement and emphasize the need to reduce the negative impacts of humans on animal movement.


Assuntos
Anfíbios , Ecossistema , Animais , Aves , Humanos , Mamíferos , Répteis
10.
Sci Total Environ ; 775: 145771, 2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-33621874

RESUMO

Underlying drivers of species extinctions need to be better understood for effective conservation of biodiversity. Nearly half of all amphibian species are at risk of extinction, and pollution may be a significant threat as seasonal high-level agrochemical use overlaps with critical windows of larval development. The potential of environmental chemicals to reduce the fitness of future generations may have profound ecological and evolutionary implications. This study characterized effects of male developmental exposure to environmentally relevant concentrations of the anti-androgenic pesticide linuron over two generations of offspring in Xenopus tropicalis frogs. The adult male offspring of pesticide-exposed fathers (F1) showed reduced body size, decreased fertility, and signs of endocrine system disruption. Impacts were further propagated to the grand-offspring (F2), providing evidence of transgenerational effects in amphibians. The adult F2 males demonstrated increased weight and fat body palmitoleic-to-palmitic acid ratio, and decreased plasma glucose levels. The study provides important cross-species evidence of paternal epigenetic inheritance and pollutant-induced transgenerational toxicity, supporting a causal and complex role of environmental contamination in the ongoing species extinctions, particularly of amphibians.


Assuntos
Poluentes Ambientais , Praguicidas , Anfíbios , Animais , Masculino , Praguicidas/toxicidade , Reprodução , Xenopus
11.
Environ Monit Assess ; 193(2): 58, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33439357

RESUMO

Land use alteration such as livestock grazing can affect water quality in habitats of at-risk wildlife species. Data from managed wetlands are needed to understand levels of exposure for aquatic life stages and monitor grazing-related changes afield. We quantified spatial and temporal variation in water quality in wetlands occupied by threatened Oregon spotted frog (Rana pretiosa) at Klamath Marsh National Wildlife Refuge in Oregon, United States (US). We used analyses for censored data to evaluate the importance of habitat type and grazing history in predicting concentrations of nutrients, turbidity, fecal indicator bacteria (FIB; total coliforms, Escherichia coli (E. coli), and enterococci), and estrogenicity, an indicator of estrogenic activity. Nutrients (orthophosphate and ammonia) and enterococci varied over time and space, while E. coli, total coliforms, turbidity, and estrogenicity were more strongly associated with local livestock grazing metrics. Turbidity was correlated with several grazing-related constituents and may be particularly useful for monitoring water quality in landscapes with livestock use. Concentrations of orthophosphate and estrogenicity were elevated at several sites relative to published health benchmarks, and their potential effects on Rana pretiosa warrant further investigation. Our data provided an initial assessment of potential exposure of amphibians to grazing-related constituents in western US wetlands. Increased monitoring of surface water quality and amphibian population status in combination with controlled laboratory toxicity studies could help inform future research and targeted management strategies for wetlands with both grazing and amphibians of conservation concern.


Assuntos
Qualidade da Água , Áreas Alagadas , Anfíbios , Animais , Ecossistema , Monitoramento Ambiental , Escherichia coli , Gado , Oregon
12.
Chemosphere ; 271: 129598, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33465620

RESUMO

In situ bioassays provide valuable information about the environment and offer more realistic results than usual laboratory experiments. The aim of this study was to evaluate the quality of water bodies from the lower Paraná River basin, the second most important in South America, through analysis of physiochemical parameters, metals and pesticides and in situ exposure of Rhinella fernandezae larvae to assess oxidative stress biomarkers. The sites were: S1(Morejón stream, reference); S2, S3(De la Cruz stream upstream and downstream, respectively) and S4(Arrecifes River). In all sites, dissolved oxygen was low, atrazine was detected and Cu was higher than the limit for aquatic life protection. According to the water quality index, S2, S3 and S4 presented bad water quality, while S1 good water quality. Larvae were exposed in situ for 96h in order to analyze: lipid peroxidation(TBARS) as oxidative damage, antioxidant enzymatic (catalase-CAT-, superoxide dismutase-SOD- and glutathione s-transferase-GST-) and non-enzymatic defenses (reduced glutathione-GSH-). Larvae exposed in the most impacted sites (S2, S3 and S4) presented oxidative stress since the levels of TBARS were around 2 times higher than in S1. Also, the other oxidative stress biomarkers were altered in larvae exposed at S2, S3 and S4. These results highlight the importance of analyzing oxidative stress biomarkers during in situ exposures since they are useful tools for documenting the extent of exposure at sublethal levels. The complex pollution of the water bodies affected the exposed larvae, which may jeopardize the native populations.


Assuntos
Poluentes Químicos da Água , Qualidade da Água , Anfíbios , Animais , Biomarcadores/metabolismo , Catalase/metabolismo , Glutationa/metabolismo , Glutationa Transferase/metabolismo , Larva/metabolismo , Estresse Oxidativo , América do Sul , Superóxido Dismutase/metabolismo , Poluentes Químicos da Água/toxicidade
14.
Gene ; 777: 145462, 2021 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-33515725

RESUMO

A universal phenomenon of using synonymous codons unequally in coding sequences known as codon usage bias (CUB) is observed in all forms of life. Mutation and natural selection drive CUB in many species but the relative role of evolutionary forces varies across species, genes and genomes. We studied the CUB in mitochondrial (mt) CO genes from three orders of Amphibia using bioinformatics approach as no work was reported yet. We observed that CUB of mt CO genes of Amphibians was weak across different orders. Order Caudata had higher CUB followed by Gymnophiona and Anura for all genes and CUB also varied across genes. Nucleotide composition analysis showed that CO genes were AT-rich. The AT content in Caudata was higher than that in Gymnophiona while Anura showed the least content. Multiple investigations namely nucleotide composition, correspondence analysis, parity plot analysis showed that the interplay of mutation pressure and natural selection caused CUB in these genes. Neutrality plot suggested the involvement of natural selection was more than the mutation pressure. The contribution of natural selection was higher in Anura than Gymnophiona and the lowest in Caudata. The codons CGA, TGA, AAA were found to be highly favoured by nature across all genes and orders.


Assuntos
Anfíbios/genética , Uso do Códon/genética , Genes Mitocondriais/genética , Anfíbios/metabolismo , Animais , Evolução Biológica , Códon/genética , Biologia Computacional , Complexo de Proteínas da Cadeia de Transporte de Elétrons/genética , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Evolução Molecular , Mutação/genética , Seleção Genética/genética
15.
Vet Clin North Am Exot Anim Pract ; 24(1): 197-210, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33189251

RESUMO

Amphibians represent a diverse group of animals with highly varied behaviors depending on their anatomy, physiology, and ecological niche. Behavioral and welfare issues in amphibians are frequent in captive settings and warrant evaluation. Welfare criteria and clinical diagnostic assays when combined with a comprehension of the natural history of a species are useful tools to improve both the well-being of the individual animal and the population. Correction of environmental factors that affect behavior and, secondarily, survival and reproduction is important in captivity and for the conservation of wild populations.


Assuntos
Anfíbios/fisiologia , Criação de Animais Domésticos , Comportamento Animal , Animais de Estimação , Bem-Estar do Animal , Animais
16.
Sci Total Environ ; 753: 141987, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-32911169

RESUMO

Artificial ponds are increasingly created for the services they provide to humans. While they have the potential to offer habitats for freshwater biodiversity, their contribution to regional diversity has hardly been quantified. In this study, we assess the relative contribution of five types of artificial ponds to regional biodiversity of five different regions, studying amphibians, water beetles and freshwater snails. This biodiversity is also compared with that observed in natural ponds from three of the investigated regions. Our results indicate that artificial ponds host, on average, about 50% of the regional pool of lentic species. When compared to natural ponds, the artificial ponds always supported a substantially lower alpha richness (54% of the natural pond richness). The invertebrate communities presented high values of beta diversity and were represented by a restricted set of widely distributed species, and by numerous rare species. There were discrepancies among the taxonomic groups: overall, amphibians benefited most from the presence of artificial ponds, since 65% of the regional lentic species pools for this group was found in artificial ponds, whereas 43% and 42% was observed in the case of beetles and snails, respectively. However, each invertebrate group was promptly the most benefited animal group in a single pond type. Therefore, artificial pond types were complementary among them in terms of contribution to regional diversity of the three animal groups. Based on these results, we forecast that future human-dominated landscapes in which most ponds are artificial will be particularly impoverished in terms of freshwater biodiversity, underlining the need to conserve existing natural ponds and to create new "near-natural" ponds. However, if properly designed and managed, artificial ponds could make a substantial contribution to support freshwater biodiversity at a regional scale. Furthermore, the number and diversity of artificial ponds must be high in each considered landscape.


Assuntos
Biodiversidade , Tanques , Anfíbios , Animais , Ecossistema , Humanos , Invertebrados
17.
Biochim Biophys Acta Proteins Proteom ; 1869(1): 140553, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33002629

RESUMO

The discovery of enzyme-derived d-amino acid-containing peptides (DAACPs) that have physiological importance in the metazoan challenges previous assumptions about the homochirality of animal proteins while simultaneously revealing new analytical challenges in the structural and functional characterization of peptides. Most known DAACPs have been identified though laborious activity-guided purification studies or by homology to previously identified DAACPs. Peptide characterization experiments are increasingly dominated by high throughput mass spectrometry-based peptidomics, with stereochemistry rarely considered due to the technical challenges of identifying l/d isomerization. This review discusses the prevalence of enzyme-derived DAACPs among animals and the physiological consequences of peptide isomerization. Also highlighted are the analytical methods that have been applied for structural characterization/discovery of DAACPs, including results of several recent studies using non-targeted discovery methods for revealing novel DAACPs, strongly suggesting that more DAACPs remain to be uncovered.


Assuntos
Peptídeos Catiônicos Antimicrobianos/fisiologia , Conotoxinas/química , Oligopeptídeos/fisiologia , Peptídeos Opioides/fisiologia , Peptídeos Cíclicos/fisiologia , Aminoácidos/química , Aminoácidos/metabolismo , Anfíbios/classificação , Anfíbios/fisiologia , Animais , Peptídeos Catiônicos Antimicrobianos/química , Artrópodes/classificação , Artrópodes/fisiologia , Mamíferos/classificação , Mamíferos/fisiologia , Moluscos/classificação , Moluscos/fisiologia , Oligopeptídeos/química , Peptídeos Opioides/química , Peptídeos Cíclicos/química , Filogenia , Estereoisomerismo
18.
PLoS Comput Biol ; 16(12): e1008540, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33370775

RESUMO

Reasoning about the factors underlying habitat connectivity and the inter-habitat movement of species is essential to many areas of biological inquiry. In order to better describe and understand the ways in which the landscape may support species movement, an increasing amount of research has focused on identification of paths or corridors that may be important in providing connectivity among habitat. The least-cost path problem has proven to be an instrumental analytical tool in this sense. A complicating aspect of such path identification methods is how to best reconcile and integrate the array of criteria or objectives that species may consider in traversal of a landscape. In cases where habitat connectivity is thought to be influenced or guided by multiple objectives, numerous solutions to least-cost path problems can exist, representing tradeoffs between the objectives. In practice though, identification of these solutions can be very challenging and as such, only a small proportion of them are typically examined leading to a weak characterization of habitat connectivity. To address this computational challenge, a multiobjective optimization framework is proposed. A generalizable multiobjective least-cost path model is first detailed. A non-inferior set estimation (MONISE) algorithm for identifying supported efficient solutions to the multiobjective least-cost path model is then described. However, it is well known that unsupported efficient solutions (which are equally important) can also exist, but are typically ignored given that they are more difficult to identify. Thus, to enable the identification of the full set of efficient solutions (supported and unsupported) to the multiobjective model, a multi-criteria labeling algorithm is then proposed. The developed framework is applied to assess different conceptualizations of habitat connectivity supporting amphibian movement in a wetland system. The results highlight the range of tradeoffs in characterizations of connectivity that can exist when multiple objectives are thought to contribute to movement decisions and that the number of unsupported efficient solutions (which are typically ignored) can vastly outweigh that of the supported efficient solutions.


Assuntos
Anfíbios/fisiologia , Simulação por Computador , Ecossistema , Movimento , Algoritmos , Animais , Conservação dos Recursos Naturais/métodos
19.
Dis Aquat Organ ; 142: 171-176, 2020 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-33331284

RESUMO

Infection by the chytrid fungus Batrachochytrium dendrobatidis (Bd) is a major threat to amphibians and has caused catastrophic global declines of amphibian populations. Some studies have detected a seasonal pattern of infection associated with the local climate, and although most of them have focused on investigating the seasonality of Bd in relation to its impacts on amphibians, fewer have aimed to understand the chytrid persistence in the amphibian assemblage over seasons by investigating reservoir hosts. Since tadpoles are generally tolerant to Bd infection, they often play a relevant role in local disease dynamics. Thus, we hypothesized that tadpoles of Boana faber, a species that can be found in permanent ponds throughout the seasons, would function as Bd reservoirs. We therefore investigated Bd infection prevalence in tadpoles of this species over 2 yr in a nature reserve. As expected, we detected a seasonal variation of Bd infection, with a higher prevalence of Bd during the coldest months (winter) when compared to the warmer months (summer). Interestingly, our seasonal-trend decomposition analysis showed that Bd prevalence is increasing annually in the area, which could represent either a natural fluctuation of this pathogen, or an imminent threat to that anuran assemblage. With this study, we highlight the tadpole of B. faber as a potential reservoir for Bd, and we suggest that monitoring Bd in such hosts could be a powerful tool for identifying priority areas for amphibian conservation.


Assuntos
Quitridiomicetos , Micoses , Anfíbios , Animais , Larva , Micoses/epidemiologia , Micoses/veterinária , Tanques , Prevalência , Estações do Ano
20.
Dis Aquat Organ ; 142: 177-187, 2020 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-33331285

RESUMO

Amphibians have been facing a pandemic caused by the deadly fungus Batrachochytrium dendrobatidis (Bd). Although studies have elucidated cutaneous and homeostatic disturbances, it is still unknown if the hepatic function can be affected or if hepatic effects differ among host species. Thus, we evaluated the effects of an experimental Bd infection on the liver (histopathology and the hepatosomatic index) of 2 anuran species (Xenopus laevis and Physalaemus albonotatus) with different susceptibilities to Bd infection and compared them to uninfected controls. Bd infection increased the melanomacrophage cell area and induced leukocyte infiltration in both species. The effects were more pronounced in the sensitive species, P. albonotatus, which showed severe reduction in glycogen stores and liver atrophy, due to energetic imbalance. Hepatocytes of P. albonotatus also showed ballooning degeneration (vacuolization), which could lead to cell death and liver failure. Our results provide evidence that although the sensitive species showed more severe effects, the tolerant species also had hepatic responses to the infection. These findings indicate that hepatic function can play an important role in detoxification and in immune responses to chytridiomycosis, and that it may be used as a new biomarker of health status in chytrid infections.


Assuntos
Quitridiomicetos , Micoses , Anfíbios , Animais , Anuros , Suscetibilidade a Doenças/veterinária , Fígado , Micoses/veterinária
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