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Relationships between snout-vent length of individuals of Bothrops atrox (A) and number of individuals per plot (B), and log 10 distance from the streams. Black circles 5 one plot, squares 5 two overlapped plots, triangle 5 three overlapped plots, white circle 5 four overlapped plots.
Contexts in source publication
Context 1
... than uniformly distributed plots (ANOVA F 1,44 5 35.1, P , 0.001), and individuals were larger in riparian plots (ANOVA F 1,50 5 6.692, P 5 0.01), with larger snakes closer to streams. However, little of the variation in SVL (R 2 5 0.08, P , 0.02) was associated with whether the plot was within 10 m from streams or more than 100 m from streams ( Fig. ...
Context 2
... (L) and the logarithm of distance from streams (logD) explained about 20% of the variance in the number (N) of snakes encountered (N 5 3.33 + [20.23] L+ [20.003] logD, R 2 5 0.2, P 5 0.008). The evidence for an effect of litter depth alone was equivocal (P 5 0.07), but the number encountered had a strong negative and nonlinear relationship ( Fig. 2B) with distance from the stream (P 5 0.003). Within uniformly distributed plots and within riparian plots, none of the variables influenced the number of individuals encountered (P . 0.28 in all ...
Context 3
... 32 individuals we found no difference in detection distance (Fig. 2B) between riparian and uniformly distribut- ed plots (Kolmogorov-Smirnov 5 0.31, P 5 0.47). Distance sampling showed variation of less than 11% in detection probabilities between riparian and uniformly distributed plots, in models without covariates (9.8%), including SVL (4.9%) and sex ...
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Citations
... In the research year, however, the meeting rate was atypical. Despite not being aquatic, B. atrox has a strong relation with water [32] being usually found in branches near stream. During 2023' flood, between April and June, dwellers of all communities reported having found little or no specimens of B. atrox until that period. ...
Background
Snakebites are considered a neglected tropical disease responsible for many accidents, some fatal, and are related to poverty. The Brazilian Amazon has the highest incidence of snakebites per inhabitant, with the state of Pará having the most reported cases. For those who have difficult access to hospitals and pharmacies, this issue is even more urgent.
Methods
In this research, we worked together with the population of five riverine communities in Aritapera (Santarém-PA), a fluvial island located in the Lower Amazon floodplain (várzeas), in order to identify the species of venomous snakes and create a record of snakebites in the region and treatments carried out.
Results
Dwellers reported a high frequency of encounters throughout the year and mentioned five venomous ethnospecies, although we identified only Bothrops atrox. Approximately 28.7% of the participants had already been bitten, and in 15.8% of the interviews, they mentioned deaths from snakebites. The treatments varied between hospitalization (42.8%), home treatments (23.8%), both together (25.4%) and healers (7.9%). There were cases where no treatment, or just religious treatment, was performed. In general, no serious sequelae were reported. Although home treatments were more common in the past, many people maintained the practice of using them before going to the hospital. Among the most used are Pau X and the fat of the Amazon River Dolphin. The latter appears to be a recent discovery by locals and is considered very efficient both for humans and animals.
Conclusion
Difficult access to health centers, a lack of energy to store antivenom and a high rate of encounters with snake place Aritapera dwellers in a vulnerable situation regarding snakebite accidents. In this context, they discovered treatments that improved their well-being until hospitalization. As the Amazon River dolphin is an endangered species, the use of its fat requires attention. In this sense, the dissemination of this knowledge is important to encourage studies that investigate which properties of this fat act as counterpoisons. By discovering substitutes that can be incorporated in other rural and remote communities, an economic and ecologically viable option for the health of residents can be promoted, in addition to valuing traditional knowledge.
... 27 This species is generally associated with water, with a preference for humid environments near streams, lakes, or wetlands, and it plays an important ecological role in tropical rainforests. [27][28][29] This species is responsible for almost 90% of snakebites in the Brazilian Amazon region 30 and has been the subject of numerous ecological and morphological studies. 26,27,[29][30][31][32][33][34][35] Yet there remain no investigations into the embryological development of B. atrox. ...
... [27][28][29] This species is responsible for almost 90% of snakebites in the Brazilian Amazon region 30 and has been the subject of numerous ecological and morphological studies. 26,27,[29][30][31][32][33][34][35] Yet there remain no investigations into the embryological development of B. atrox. Therefore, our goals are (1) to describe and illustrate, for the first time, the embryonic development of the Amazonian pit viper Bothrops atrox, using detailed color-image analysis across different embryonic stages, (2) to compare the development of the pit organ in Serpentes clade, and (3) to compare the development of the head scalation in Bothrops atrox with the adult head scalation that diagnose the genus Bothrops. ...
Background
Bothrops atrox is a pit viper with a loreal pit organ, and its embryological development remains undescribed. Here, we provide a comprehensive description of the embryology of B. atrox, focusing on the loreal pit organ and cephalic scales.
Results
We characterized 13 developmental stages of B. atrox based on external features consistent with the embryogenesis of previously described snake species. The loreal pit organ originates from the circumorbital region and migrates to its final position. In Crotalinae, the pit organ first becomes visible at stage 28, whereas in Pythonidae labial, pit organs appear at Stage 35. Pit organs evolved independently three times in Serpentes, encompassing Boidae, Pythonidae, and Crotalinae. Boidae lacks embryological information for pit organs. Furthermore, we observed that head scalation onset occurs at Stage 33 in B. atrox, with fusion of scales surrounding the loreal pit organ.
Conclusions
The embryology of pit organs in Pythonidae and Boidae species remains poorly understood. Our detailed embryological descriptions are critical for proposing developmental scenarios for pit organs and guiding future research on these structures.
... This is an important factor in determining assemblage structure (Pianka 1966;Keller et al. 2009). Riparian zones also concentrate certain species because of habitat selection (Fraga et al. 2013), and are considered important for maintaining regional biodiversity (Bub et al. 2004;Lehmkuhl et al. 2007;Bueno et al. 2012). Increased spatial heterogeneity may facilitate resource-partitioning, increase the availability of refuges and microhabitats, and influence species richness and composition (Hutchinson 1957;Pianka 1974;Schall & Pianka 1978;Sebens 1991). ...
The use of lizards as model organisms in ecological studies is based on their success in occupying a
great diversity of habitats, and some species are closely tied to the environment, which is disadvantaged by the
legislation of several countries concerning land use. Our aim was to relate lizard species distribution patterns in
rainforest environments to variation in environmental gradients, and provide ecologically based metrics for estab-
lishing buffer zones around streams. Lizards were sampled three times in 41 standardised transects near Manaus,
Brazil, only in dry season, with Time Limited Visual Search associated with raking through leaf litter. We
recorded 20 species from 10 families and used non-metric multidimensional scaling to reduce the dimensionality
of quantitative and qualitative compositions of species. Multiple linear regression models indicated that the envi-
ronmental gradients distance to nearest stream, extent of canopy openness, vegetation density and slope did not
signi
fi
cantly in
fl
uence assemblage species distribution, with an indication of effect of litter depth. By means of
piecewise linear regression, the use of riparian zone was estimated at
~
190 m from quantitative species composi-
tion and
~
211 m from qualitative species composition. Five species occurred only in the riparian zone. Our
results suggest that conservation of the entire riparian lizard assemblage in Amazonian rainforest is likely to
require protection of at least a 211 m buffer on either side of streams.
... Much of what is known about environmental effects on the composition of Amazonian snake assemblages is due to the implementation of a modular and standardized system of samplings known as RAPelD (Magnusson et al. 2005, 2013. By means of an unprecedented sampling effort in the biome, it is known that assemblages are environmentally structured in relation to their distance from bodies of water (Fraga et al. 2011), a pattern which was also revealed by analyzing the abundance of individual species (Fraga et al. 2013b). Furthermore, it is known that environmental variables inhibit dispersion and consequently gene flow in different ways according to the characteristics of the species (Fraga et al. 2017). ...
Most species of Amazonian snakes have wide geographic distributions. However, local
environmental factors influence the formation of assemblages in different localities. In this study, we
investigated the composition of the assemblage and the effect of environmental variables on the distribution
of the species inhabiting an upland forest in the Experimental Farm area of the Federal University of
Amazonas in Manaus, Brazil. Data collection was carried out in 24 standardized plots. Each plot was
sampled four times between July 2015 and April 2017 by active search method. We recorded 83 individuals
from 29 species belonging to six families. The richness in the study area corresponded to 78% of the snake
species and 100% of the families previously recorded for Manaus. As observed in other localities, the
most abundant species was the Amazonian lancehead (Bothrops atrox). Multiple linear regression models
did not detect any effect of environmental variables on species richness and abundance of individuals.
However, quadratic polynomial regression models revealed that intermediate canopy opening percentages
positively influence the richness and abundance of snakes. It is possible that the result is related to a
tradeoff between the thermoregulation behavior of these animals and to their susceptibility to predation.
... This epidemiological profile was reported previously in the Amazon (35,36), and probably is related to a significant higher exposition of this population group when exerting agricultural or forestry activities, in the habitat mostly selected by lancehead pit vipers. Several studies have reported on habitat use by B. atrox, the easiest snake to find in comparison to other species in Central Amazonia (46), and concluded that the species is mainly found on the ground or climb into understory vegetation, in the case of juveniles (15)(16)(17). In this study, most of the snakebites occurred in the lower limbs, suggesting that adult snakes than juveniles, are the major responsible by the human injuries, inflicted after the contact of human individuals, barefoot or with lower limbs not fully protected, with snakes using the ground to rest (especially during the day), hunt and move (15,46). ...
... Several studies have reported on habitat use by B. atrox, the easiest snake to find in comparison to other species in Central Amazonia (46), and concluded that the species is mainly found on the ground or climb into understory vegetation, in the case of juveniles (15)(16)(17). In this study, most of the snakebites occurred in the lower limbs, suggesting that adult snakes than juveniles, are the major responsible by the human injuries, inflicted after the contact of human individuals, barefoot or with lower limbs not fully protected, with snakes using the ground to rest (especially during the day), hunt and move (15,46). Some agroforestry activities developed in the Amazon are very conducive to contact of workers with snakes, such as the The copyright holder for this preprint (which was not . ...
... In this work, percentage of vegetation cover was positively related to Bothrops bite incidence, indicating that the original rainforest environment maintenance is crucial for population density in levels that warrant an intense contact rate between Bothrops individuals and humans. In this preserved environment, snakes probably find more propitious terrestrial (leaf litter) and occasionally arboreal microhabitats where these animals use the space for survival, especially in relation to prey availability (15)(16)(17)49). (49). ...
Despite significant and successful efforts in Brazil regarding snakebites in the areas of research, antivenom manufacture and quality control, training of health professionals in the diagnosis and clinical management of bites, little is known about determinants of snakebites incidence in order to further plan interventions to reduce the impact of this medical condition. Understanding the complexity of ecological interactions in a geographical region is important for prediction, prevention and control measures of snakebites. The aim of this investigation is to describe spatial distribution and identify environmental determinants of human- lancehead pit vipers ( Bothrops genus) contact resulting in injuries, in the Brazilian Amazon. Aggregated data by municipality was used to analyze the spatial distribution of Bothrops bites cases and its relationship with geographic and environmental factors. Eight geo-environmental factors were included in the analysis as independent variables: (1) tree canopy loss increase; (2) area with vegetation cover; (3) area covered by water bodies; (4) altitude; (5) precipitation; (6) air relative humidity; (7) soil moisture; and (8) air temperature. Human- lancehead pit vipers ( Bothrops genus) contact resulting in envenomings in the Amazon region is more incident in lowlands [-0.0006827 (IC95%: −0.0007705; - 0.0005949), p<0.0001], with high preserved original vegetation cover [0.0065439 (IC95%: 0.0070757; 0.0060121), p<0.0001], with heaviest rainfall [0.0000976 (IC95%: 0.0000925; 0.0001026), p<0.0001] and higher air relative humidity [- 0.0081773 (IC95%: −0.0107681; −0.0055865), p<0.0001]. This association is interpreted as the result of the higher forest productivity and abundance of pit vipers in such landscapes.
Author summary
Despite successful efforts in Brazil regarding snakebites in the areas of research, antivenom manufacture and quality control and training of health professionals, little is known about determinants of snakebites incidence in order to further plan interventions to reduce the impact of this medical condition. Understanding the complexity of ecological interactions in a geographical region is important for prediction, prevention and control measures of snakebites. The aim of this study is to describe spatial distribution and identify environmental determinants of human- lancehead pit vipers ( Bothrops genus) contact resulting in injuries, in the Brazilian Amazon. An increase in the forest productivity with a higher availability of some types of prey, such as frogs and amphibians, anurans and lizards, was suggested as a cause for the higher snake abundance in the rainy season. Probably due to the higher forest productivity and abundance of pit vipers in such landscapes, human-lancehead pit vipers contact resulting in envenomings in the Amazon region is more incident in lowlands, with high preserved original vegetation cover, with heaviest rainfall and higher air relative humidity.
Malaria is an infectious disease caused by Plasmodium spp. and it is mainly transmitted to humans by female mosquitoes of the genus Anopheles. Malaria is an important global public health problem due to its high rates of morbidity and mortality. At present, drug therapies and vector control with insecticides are respectively the most commonly used methods for the treatment and control of malaria. However, several studies have shown the resistance of Plasmodium to drugs that are recommended for the treatment of malaria. In view of this, it is necessary to carry out studies to discover new antimalarial molecules as lead compounds for the development of new medicines. In this sense, in the last few decades, animal venoms have attracted attention as a potential source for new antimalarial molecules. Therefore, the aim of this review was to summarize animal venom toxins with antimalarial activity found in the literature. From this research, 50 isolated substances, 4 venom fractions and 7 venom extracts from animals such as anurans, spiders, scorpions, snakes, and bees were identified. These toxins act as inhibitors at different key points in the biological cycle of Plasmodium and may be important in the context of the resistance of Plasmodium to currently available antimalarial drugs.
Snakes are a diverse group of terrestrial vertebrates of the order Squamata. Despite that, in the Amazonian biome, information about distribution and identification of snakes is limited when compared to other groups. Additionally, in Amazonia there is a sampling bias towards areas geographically close to urban centers and more densely populated areas. This in turn leads to false distribution gaps in poorly accessible areas of Amazonia. In this article we report the composition of snake assemblages in six areas of the Brazilian Amazonia, based on field sampling conducted over four years using standardized methods. We sampled 70 species from eight families: Typhlopidae (n=1), Leptotyphlopidae (n=1), Anillidae (n=1), Boidae (n=5), Colubridae (n=15), Dipsadidae (n=35), Elapidae (n=7), and Viperidae (n=5). The largest number of species was recorded in the Trombetas River area and the lowest in the Jatapu River area. The total beta diversity was 0.40 and the snake assemblages were structured mainly by replacement (72.5%). The time-limited search was the method that recorded the greatest number of individuals in the studied areas (44.1%) and also the greatest number of species (n=40). However, some species were recorded only by other methods such as interception by pitfall traps with directional fences. Despite the large number of species sampled in the study, no particular area comprised more than 40% of species registered in all the areas, indicating that snakes are poorly detected even with large sampling effort across multiple areas of a species distribution. Riqueza de espécies e composição de assembleias de serpentes em áreas pouco acessíveis na Amazônia brasileira.
Mechanisms generating and maintaining biodiversity at regional scales may be
evaluated by quantifying β-diversity along environmental gradients. Differences
in assemblages result in biotic complementarities and redundancies among sites,
which may be quantified through multi-dimensional approaches incorporating
taxonomic β-diversity (TBD), functional β-diversity (FBD) and phylogenetic
β-diversity (PBD). Here we test the hypothesis that snake TBD, FBD and PBD
are influenced by environmental gradients, independently of geographic distance.
The gradients tested are expected to affect snake assemblages indirectly, such as clay
content in the soil determining primary production and height above the nearest
drainage determining prey availability, or directly, such as percentage of tree cover
determining availability of resting and nesting sites, and climate (temperature and
precipitation) causing physiological filtering.We sampled snakes in 21 sampling plots,
each covering five km2, distributed over 880 kmin the central-southern Amazon Basin.
We used dissimilarities between sampling sites to quantify TBD, FBD and PBD,
which were response variables in multiple-linear-regression and redundancy analysis
models.We show that patterns of snake community composition based on TBD, FBD
and PBD are associated with environmental heterogeneity in the Amazon. Despite
positive correlations between all β-diversity measures, TBD responded to different
environmental gradients compared to FBD and PBD. Our findings suggest that
multi-dimensional approaches are more informative for ecological studies and
conservation actions compared to a single diversity measure.
Comparative phylogeography allow us to understand how shared historical circumstances have shaped the formation of lineages, by examining a broad spectrum of co-distributed populations of different taxa. However, these types of studies are scarce in the Neotropics, a region that is characterized by high diversity, complex geology, and poorly understood biogeography. Here, we investigate the diversification patterns of five lineages of amphibians and reptiles, co-distributed across the Choco and Andes ecoregions in northwestern Ecuador. Mitochondrial DNA and occurrence records were used to determine the degree of geographic genetic divergence within species. Our results highlight congruent patterns of parapatric speciation and common geographical barriers for distantly related taxa. These comparisons indicate similar biological and demographic characteristics for the included clades, and reveal the existence of two new species of Pristimantis previously subsumed under P. walkeri, which we describe herein. Our data supports the hypothesis that widely distributed Chocoan taxa may generally experience their greatest opportunities for isolation and parapatric speciation across thermal elevational gradients. Finally, our study provides critical information to predict which unstudied lineages may harbor cryptic diversity, and how geology and climate are likely to have shaped their evolutionary history.
