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Thresholds of freshwater biodiversity in response to riparian vegetation loss in the Neotropical region
No full textProtecting riparian vegetation around streams is vital in reducing the detrimental effects of environmental change on freshwater ecosystems and in maintaining aquatic biodiversity. Thus, identifying ecological thresholds is useful for defining regulatory limits and for guiding the management of riparian zones towards the conservation of freshwater biota. Using nationwide data on fish and invertebrates occurring in small Brazilian streams, we estimated thresholds of native vegetation loss in which there are abrupt changes in the occurrence and abundance of freshwater bioindicators and tested whether there are congruent responses among different biomes, biological groups and riparian buffer sizes. Mean thresholds of native vegetation cover loss varied widely among biomes, buffer sizes and biological groups: ranging from 0.5% to 77.4% for fish, from 2.9% to 37.0% for aquatic invertebrates and from 3.8% to 43.2% for a subset of aquatic invertebrates. Confidence intervals for thresholds were wide, but the minimum values of these intervals were lower for the smaller riparian buffers (50 and 100 m) than larger ones (200 and 500 m), indicating that land use should be kept away from the streams. Also, thresholds occurred at a lower percentage of riparian vegetation loss in the smaller buffers, and were critically lower for invertebrates: reducing only 6.5% of native vegetation cover within a 50-m riparian buffer is enough to cross thresholds for invertebrates. Synthesis and applications. The high variability in biodiversity responses to loss of native riparian vegetation suggests caution in the use of a single riparian width for conservation actions or policy definitions nationwide. The most sensitive bioindicators can be used as early warning signals of abrupt changes in freshwater biodiversity. In practice, maintaining at least 50-m wide riparian reserves on each side of streams would be more effective to protect freshwater biodiversity in Brazil. However, incentives and conservation strategies to protect even wider riparian reserves (~100 m) and also taking into consideration the regional context will promote a greater benefit. This information should be used to set conservation goals and to create complementary mechanisms and policies to protect wider riparian reserves than those currently required by the federal law. © 2020 British Ecological Societ
Efeito da pesca comercial e esportiva sobre os “troféus” de tucunaré-açu (Cichla temensis, Humboldt, 1821) em um trecho do médio Rio Negro, Barcelos-Amazonas
Full text linkIn the middle of the Negro River, commercial fishing and sporting activities have peacock bass as a common target. However, exploitation of the stock of this species occurs in a disorderly manner and information on how these activities occur in the region is scarce. Especially about sport fishing, which is one of the least studied fishing activities. Thus, this unprecedented study evaluates the stock of Cichla temensis in a stretch of the middle Rio Negro, where commercial and sport fishing activities occur with greater intensity. Data collection was carried out by applying semi-structured questionnaires to commercial and sport fishermen. The weight and total length of individuals caught by sport fishing were also measured. For the characterization of sport fishing, the average time of the season was recorded, which was six months, when tourism and fishing companies operate in five different modalities. The hotel-boat mode proved to be the most used by operators, as well as the oldest. For locomotion in fisheries, semi flattened canoes equipped with a 30HP engine are more used. 22 rivers were used for sport fishing, for preferential capture of the species Cichla temensis. The population analysis showed that the average total size of the speckled peacock bass tends to decrease with increasing fishing intensity. In the Generalized Linear Model performed for commercial fishing, it was possible to notice that all the predictive variables show a negative influence on the average total length, average weight and income of the fisheries, while in the GLM of sport fishing only the number of fishermen showed to exert such influence. The simulation model predicted that when fishing mortality is equal to natural mortality, there may be a reduction of 19.75 - 88.47% in the number of trophies entering the population. Even low exploitations would cause trophies to decline. The results presented here can be used for mixed management between commercial and sport fishing activities in the middle Negro River, since aspects that provide information on the scope of action, target species and stock status are known.No médio rio Negro, a pesca comercial e a esportiva têm como alvo comum o tucunaré. No entanto, a explotação sobre o estoque dessa espécie ocorre de forma desordenada e são escassas as informações sobre como essas atividades ocorrem na região. Principalmente, sobre a pesca esportiva que é uma das atividades pesqueiras menos estudadas. Assim, este estudo inédito avalia o estoque de Cichla temensis em um trecho do médio Rio Negro, onde as atividades de pesca comercial e esportiva ocorrem com maior intensidade. A coleta de dados foi realizada por meio de aplicação de questionários semiestruturados, ao pescadores comerciais e esportivos, também foi aferido o peso e comprimento total dos índividuos capturados pela pesca esportiva. Para a caracterização da pesca esportiva registrou-se o tempo médio de duração da temporada, que foi de seis meses, quando empresas as de turismo e de pesca atuam em cinco modalidades distintas. A modalidade de barco-hotel mostrou ser a mais aderida pelos operadores, assim como a mais antiga. Para a locomoção nas pescarias, as canoas semichata equipadas com motor de potência 30HP são mais utilizadas. Foram identificados 22 rios utilizados pela pesca esportiva, para captura preferencial da espécie Cichla temensis. A análise da população mostrou que o tamanho total médio dos tucunarés tende a diminuir com o aumento da intensidade de pesca. No Modelo Linear Generalizado realizado para pesca comercial, foi possível notar que todas as variáveis preditoras mostram exercer influência negativa sobre o comprimento total médio, peso médio e rendimento das pescarias, enquanto no MLG da pesca esportiva apenas o número de pescador mostrou exercer tal influência. O modelo de simulação previu que quando a mortalidade por pesca for igual a mortalidade natural, pode ocorrer uma redução de 19,75 - 88,47% no número de troféus que entram na população. Até baixas explotações causariam o declínio de troféus. Os resultados aqui apresentados podem ser utilizados para a gestão mista entre as atividades de pesca comercial e esportiva no médio Rio Negro, uma vez que são conhecidos aspectos que fornecem informações sobre abrangência de atuação, espécie alvo e status do estoque
Diversification history of clown tree frogs in Neotropical rainforests (Anura, Hylidae, Dendropsophus leucophyllatus group)
No full textGeneral consensus emphasizes that no single biological process can explain the patterns of species’ distributions and diversification in the Neotropics. Instead, the interplay of several processes across space and time must be taken into account. Here we investigated the phylogenetic relationships and biogeographic history of tree frogs in the Dendropsophus leucophyllatus species group (Amphibia: Hylidae), which is distributed across Amazonia and the Atlantic rainforests. Using Next Generation Sequencing (NGS) and double digest restriction-site associated DNA (ddRADseq), we inferred phylogenetic relationships, species limits, and temporal and geographic patterns of diversification relative to the history of these biomes. Our results indicate that the D. leucophyllatus species group includes at least 14 independent lineages, which are currently arranged into ten described species. Therefore, a significant portion of species in the group are still unnamed. Different processes were associated to the group diversification history. For instance, the Andes uplift likely caused allopatric speciation for Cis-Andean species, whereas it may also be responsible for changes in the Amazonian landscape triggering parapatric speciation by local adaptation to ecological factors. Meanwhile, Atlantic Forest ancestors unable to cross the dry diagonal biomes after rainforest's retraction, evolved in isolation into different species. Diversification in the group began in the early Miocene, when connections between Atlantic Forest and the Andes (Pacific Dominion) by way of a south corridor were possible. The historical scenario in Amazonia, characterized by several speciation events and habitat heterogeneity, helped promoting diversification, resulting in the highest species diversity for the group. This marked species diversification did not happen in Atlantic Forest, where speciation is very recent (late Pliocene and Pleistocene), despite its remarkable climatic heterogeneity. © 2020 Elsevier Inc
An inverse latitudinal gradient in infection probability and phylogenetic diversity for Leucocytozoon blood parasites in New World birds
No full textGeographic variation in environmental conditions as well as host traits that promote parasite transmission may impact infection rates and community assembly of vector-transmitted parasites. Identifying the ecological, environmental and historical determinants of parasite distributions and diversity is therefore necessary to understand disease outbreaks under changing environments. Here, we identified the predictors and contributions of infection probability and phylogenetic diversity of Leucocytozoon (an avian blood parasite) at site and species levels across the New World. To explore spatial patterns in infection probability and lineage diversity for Leucocytozoon parasites, we surveyed 69 bird communities from Alaska to Patagonia. Using phylogenetic Bayesian hierarchical models and high-resolution satellite remote-sensing data, we determined the relative influence of climate, landscape, geography and host phylogeny on regional parasite community assembly. Infection rates and parasite diversity exhibited considerable variation across regions in the Americas. In opposition to the latitudinal gradient hypothesis, both the diversity and prevalence of Leucocytozoon parasites decreased towards the equator. Host relatedness and traits known to promote vector exposure neither predicted infection probability nor parasite diversity. Instead, the probability of a bird being infected with Leucocytozoon increased with increasing vegetation cover (NDVI) and moisture levels (NDWI), whereas the diversity of parasite lineages decreased with increasing NDVI. Infection rates and parasite diversity also tended to be higher in cooler regions and higher latitudes. Whereas temperature partially constrains Leucocytozoon diversity and infection rates, landscape features, such as vegetation cover and water body availability, play a significant role in modulating the probability of a bird being infected. This suggests that, for Leucocytozoon, the barriers to host shifting and parasite host range expansion are jointly determined by environmental filtering and landscape, but not by host phylogeny. Our results show that integrating host traits, host ancestry, bioclimatic data and microhabitat characteristics that are important for vector reproduction are imperative to understand and predict infection prevalence and diversity of vector-transmitted parasites. Unlike other vector-transmitted diseases, our results show that Leucocytozoon diversity and prevalence will likely decrease with warming temperatures. © 2019 The Authors. Journal of Animal Ecology © 2019 British Ecological Societ
Desenvolvimento embrionário e diferenciação gonadal de Podocnemis unifilis (Testudines: Podocnemididae) em temperatura controlada
Full text linkThis work aimed to describe the external morphological characters and gonadal differentiation during the embryonic development of Podocnemis unifilis at controlled temperature. 100 eggs were collected and incubated in an artificial incubator. The incubation period was 60 days, with an average incubation temperature of 31.8ºC. Macroscopic analyzes, light microscopy and transmission electron microscopy were performed. The main characteristics used to describe and compare embryonic development were: head, mandibular process, eyes, limbs, carapace and plastron. In gonadal development, primordial germ cells (CGPs) were only visualized from the 7th day of incubation, and were located in the posterior region of the embryo's body and between the 9th and 11th incubation it was possible to observe the migration of the CGPs from the yolk sac towards the ventromedial region of the primitive mesonephral wall. At 20 days of development, the undifferentiated gonad is established and two distinct regions are identified, the external cortical region characterized by the presence of CGPs, and the internal medullary region where the primitive sexual cords were present. The gonadal differentiation started after 35 days of incubation observing the beginning of the organization of the sexual cords for the formation of the seminiferous tubules. All the gonads analyzed in this study differed, forming testicles. Morphological studies of embryonic development and gonadal characterization generate information about the reproductive biology of species, and this information helps in research to develop management strategies and / or making existing methods more efficient.Esse trabalho objetivou descrever os caracteres morfológicos externos e diferenciação gonadal durante o desenvolvimento embrionário de Podocnemis unifilis em temperatura controlada. Foram coletados 100 ovos e incubados em incubadora artificial. O período de incubação foi de 60 dias, com temperatura média de incubação de 31,8ºC. Foram realizadas análises macroscópicas, microscopia de luz e microscopia eletrônica por transmissão. As principais características utilizadas para descrição e comparação do desenvolvimento embrionário foram: cabeça, processo mandibular, olhos, membros, carapaça e plastrão. No desenvolvimento gonadal as células germinativas primordiais (CGPs) só foram visualizadas a partir do 7º dia de incubação, e se localizavam na região posterior do corpo do embrião e entre os dias 9 e 11 de incubação foi possível observar a migração das CGPs a partir do saco vitelínico em direção a região ventromedial da parede do mesonefro primitivo. Aos 20 dias de desenvolvimento a gônada indiferenciada está estabelecida sendo identificadas duas regiões distintas, a região cortical externa caracterizada pela presença de CGPs, e a região medular interna onde os cordões sexuais primitivos foram presentes. A diferenciação gonadal teve início a partir de 35 dias de incubação observando o início da organização dos cordões sexuais para a formação dos túbulos seminíferos. Todas as gônadas analisadas nesse estudo se diferenciaram formando testículos. Os estudos morfológicos do desenvolvimento embrionário e a caracterização gonadal geram informações acerca da biologia reprodutiva das espécies, e essas informações auxiliam em pesquisas para elaboração de estratégias de manejo e/ou tornando os métodos já existentes mais eficientes
Moist Heat Overcomes Physical Dormancy at the Seed Coat Lens in Schizolobium parahyba var. amazonicum
No full textEvaluation of the anti-snakebite, antimicrobial and antioxidant potential of Philodendron megalophyllum Schott (Araceae), traditionally used in accidents caused by snakes in the western region of Pará, Brazil
No full textEthnopharmacological relevance: In the region of Western Pará, Amazonia, Brazil, Philodendron megalophyllum is widely used for the treatment of envenomations caused by bites from venomous snakes. The traditional use of plants is usually done through oral administration of an infusion (decoction) soon after the bite occurs. The efficiency of aqueous extracts of P. megalophyllum was demonstrated for blocking the activity of the venom of Bothrops sp., but only for a pre-incubation protocol (venom:extract), which fails to simulate the real form of use of this species. In this context, the objective of this research was to evaluate the anti-snakebite potential of the aqueous extract of P. megalophyllum to inhibit for the biological activity induced by Bothrops atrox venom (BaV) using traditional treatment methods. Material and methods: Initially, an aqueous extract using the stem of P. megalophyllum (AEPm) was prepared following the standard procedure used by the residents of the rural area along the Tapajós River (Eixo Forte region) in Santarém, PA, Brazil. The phytochemical profile of AEPm was conducted using thin layer chromatography (TLC) and phenolic compounds were quantified through colorimetric trials. The cytotoxicity of AEPm was evaluated using the MRC-5 human fibroblast line, and the antioxidant potential was measured using DPPH methods and cell culture. AEPm antimicrobial action was evaluated by the 96-well plate microdilution and the minimum inhibitory concentration (MIC) methods using 18 types of microorganisms including bacteria that are present in the oral cavity of snakes. AEPm blocking potential was tested against BaV activity in vitro (fibrinolytic) and in vivo (defibrinating and hemorrhagic). In order to test for an interaction between BaV and AEPm SDS-PAGE electrophoresis was conducted. Results: The presence of coumarins, fatty acids, and hydrolysable tannins were detected in the AEPm. The colorimetric trials showed that AEPm had a high concentration of condensed tannins (20.1 ± 1.2%). The potential of AEPm for blocking of hemorrhagic and fibrinolytic activity of BaV showed a maximum reduction of 86.1% and 96.5%, respectively, for the pre-incubation protocol (1:10, venom:extract). However, when the extract was administered orally there was no significant blocking of these activities. The interaction of BaV and AEPm showed a modification of the profile of proteic bands when compared to the pattern of bands obtained from the BaV alone. The AEPm was not considered toxic, demonstrated antioxidant activity, and was capable of reducing the growth of 10 of the 18 studied microorganisms. Conclusion: Although the stem of P. megalophyllum is indicated by traditional medicine techniques as effective against snakebites, the extract, when tested orally was not able to significantly inhibit (p ˃ 0.05) hemorrhage and defibrinating activity induced by the B. atrox venom. On the other hand, the extract yielded a promising result with respect to antioxidant and antimicrobial potential, and after further studies it could be used as a complementary treatment for localized action and secondary infections that frequently occur with snakebites from the genus of Bothrops sp. © 2020 Elsevier Lt
Productivity and bioactivity of enokipodins A–D of Flammulina rossica and Flammulina velutipes
No full textEnokipodins are antimicrobial sesquiterpenes produced by Flammulina velutipes in a mycelial culture medium. To date, enokipodin production has not been reported in other members of the genus Flammulina. Hence, in this study, the production of enokipodins A, B, C, and D by F. velutipes and F. rossica was investigated. Some strains of F. rossica were confirmed to produce at least one of the four enokipodins in the culture medium. However, some strains of F. velutipes did not produce any of the enokipodins. In an antibacterial assay using liquid medium, enokipodin B showed the strongest growth inhibitory activity against Bacillus subtilis among the four types of enokipodins. Enokipodin B inhibited the spore germination of some plant pathogenic fungi. Enokipodins B and D exerted moderate anti-proliferative activity against some cancer cell lines, and enokipodins A and C inhibited the proliferation of the malarial parasite, Plasmodium falciparum. © 2020, © 2020 Japan Society for Bioscience, Biotechnology, and Agrochemistry
Desvinculando as etapas da especiação: fatores geográficos levam a mudanças no sinal sexual de uma rãzinha-de-liteira por meio da variação do tamanho corporal
Full text linkGeographical and environmental distances influence the divergence of characters between biological populations, especially on a macro spatial scale, making it difficult to interpret the individual contribution of these predictor variables in the process of differentiation between populations. Anurans are excellent models for multi-character evolutionary studies, due to their low vagility and frequent territoriality, causing certain environmental changes to result in barriers that isolate populations. Accordingly, we propose to test the correlation of environmental and geographical distances with phenotypic and genotypic population characters in the absence of evident vicariant barriers using as a study model an Amazonian litter-frog. We tested the general hypothesis that geographic and environmental differentiations affect the variation in the morphometric, acoustic and genetic characters of Allobates sumtuosus along a latitudinal gradient at a fine spatial scale. All data sets with the exception of those involving genetic distance showed correlation. Controlling the effect of the different data sets, we observed that the geographical distance showed a greater number of correlations, with an explanatory force always greater than 60%. The geographical distance associated with the environmental distance likely shapes the acoustic characters of populations of A. sumtuosus by means of pressures on body size. This is because the climatic environmental gradient along the latitudinal gradient results in changes to the area-volume relationship of individuals, maximizing survival rate and resulting in larger body sizes at locations closer to the Equator. Consequently, the acoustic signals diverge due to variations in the organs involved in vocalization. Despite showing the presence of an intrapopulation genetic structure for this species, this structure was not associated with phenotypic variations. In summary, this study breaks down the stages of speciation in an Amazonian frog, demonstrating that environmental factors can lead to changes in the sexual signal of a litter-frog due to the variation in body size.As distâncias geográfica e ambiental influenciam a divergência de caracteres entre populações biológicas, especialmente em escala macroespacial, dificultando a interpretação da contribuição individual dessas variáveis preditoras no processo de diferenciação entre populações. Os anuros são excelentes modelos para estudos evolutivos de vários caracteres, devido à sua baixa vagilidade e frequente territorialidade, fazendo com que certas mudanças ambientais resultem em barreiras que isolam populações. Nesse sentido, propomos testar a correlação de distâncias ambientais e geográficas com caracteres fenotípicos e genotípicos populacionais na ausência de barreiras vicariantes evidentes, usando como modelo de estudo um sapo de liteira na Amazônia. Testamos a hipótese geral de que as diferenciações geográficas e ambientais afetam a variação nos caracteres morfométricos, acústicos e genéticos de Allobates sumtuosus ao longo de um gradiente latitudinal em uma escala espacial fina. Todos os conjuntos de dados, com exceção dos que envolvem distância genética, apresentaram correlação. Controlando o efeito dos diferentes conjuntos de dados, observamos que a distância geográfica apresentou o maior número de correlações, com uma força explicativa sempre superior a 60%. A distância geográfica associada à distância ambiental provavelmente molda os caracteres acústicos das populações de A. sumtuosus por meio de pressões no tamanho corporal. Isso ocorre porque o gradiente ambiental climático ao longo do gradiente latitudinal resulta em alterações na relação área-volume dos indivíduos, maximizando a taxa de sobrevivência e resultando em tamanhos corporais maiores em locais mais próximos do Equador. Consequentemente, os sinais acústicos divergem devido a variações nos órgãos envolvidos na vocalização. Apesar de mostrar a presença de uma estrutura genética intrapopulacional para esta espécie, essa estrutura não foi associada a variações fenotípicas. Em resumo, este estudo divide os estágios de especiação em um sapo da Amazônia, demonstrando que fatores ambientais podem levar a alterações no sinal sexual de uma rãzinha-de-liteira devido à variação no tamanho do corpo