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Delimiting biogeographic regions based on occurrence data is an interesting approach to investigating processes behind biodiversity distribution patterns. Comparing spatial scales and identifying predictor variables of biogeographic regions have wide application for biodiversity conservation. In this study we used a comprehensive database containing more than thirty years of horse fly records to estimate species richness, endemism, and species composition, and regionalize the Amazon biogeographically. We compared five spatial scales defined by grid size (1–5º), and test five hypotheses (elevation, climate, vegetation cover, and two regionalizations from the literature) to identify predictors of the biogeographic regions. Endemism, species richness and composition were predicted by different sets of predictor variables, although the models were highly dependent on spatial scale. We identified three well-defined biogeographic regions, which have been formed by a combination of geographic distance, climate and historical factors converging with some theories proposed for mammals. Our models indicated dispersal as a key factor for regionalization, as it can be constrained by a combination of climate and historical processes changing habitats over time, although this finding was highly dependent on spatial scale. We showed that horse flies are interesting models for biogeography although they have been historically neglected. [ABSTRACT FROM AUTHOR]

Morphological patterns may vary spatially in response to adaptations to regional environmental conditions. In fossorial animals, edaphic gradients potentially predict intra and interspecific morphological variation because they can limit dispersal and select morphotypes. We measured morphological traits of South American worm lizards, including three Amphisbaena and two Leposternon species, to test whether inter- and intraspecific morphological variation and morphotype distribution are predicted by edaphic gradients measured at different soil profiles. Interspecifically, we found that the variation in head length is mainly predicted by the chemical edaphic structure, which can be explained by spatial variation in prey availability. The variation in the width of the prefrontal and frontal shields was mainly predicted by clay and sand-soil contents, which can be explained by relationships of force and friction associated with digging. Intraspecifically, we found that the effects of edaphic gradients on morphological variation reflects the level of specialization to dig, since the most adapted species were mainly affected by variables measured in deeper soil profiles. We also show that soil-mediated intraspecific morphological variation shape morphotype distribution across different biomes that form the South American dry diagonal, which are discussed in light of biological, ecological, and biogeographic premises. [ABSTRACT FROM AUTHOR]

River damming by hydroelectric plants interrupts the continuity of rivers and causes the flooding of adjacent terrestrial ecosystems. Assessments of the impacts of major hydroelectric dams on species and the functional responses of communities to flooding are scarce. We used data from eight years of forest monitoring around a - 100-km section of the Madeira River upstream of the Santo Antônio Dam in southwestern Brazilian Amazonia to investigate the effects of forest inundation on estimates of functional diversity and frequency of trait occurrence in pre- and post-flooding anuran assemblages. Lowland forests hosted higher functional diversity and more unique functional composition than unflooded areas sampled before and after reservoir filling. Functional richness was not affected by reservoir filling. Frequencies of arboreal anurans that lay their eggs in tree cavities or water and those that complete larval development in water were higher in flooded forest plots. In unflooded plots during the post-filling stage, there was an increase in the average frequency of nocturnal anurans and a decline in the abundance of fossorial and diurnal species. The average frequency of large-bodied anurans increased after river damming to levels similar to those of flooded plots. Our study indicates that anurans whose reproductive modes are associated with riparian and floodplain forests are most sensitive to permanent reservoir flooding. We recommend that efforts to mitigate the effects of hydropower infrastructure should include the protection of intact seasonally flooded lowland forests. [ABSTRACT FROM AUTHOR]

Aim: Distinguishing ecological and evolutionary processes that structure assemblages can provide a comprehensive vision of the variation in species turnover in heterogeneous regions. However, the causes of spatial variation in organism assemblies in most of the Amazon still require further studies. In view of this, our objective was to determine the relative roles of species interactions, categorical and continuous environmental filters and isolation by distance in the taxonomic and functional composition of lizard assemblages. Location: Amazonian rainforest. Taxon: Lacertilia. Methods: We sampled 14 sites along 880 km in the Madeira‐Purus interfluvial region, central‐south‐western Amazonia. We used multiple linear models applied to distance matrices, spatial correlograms and partitioned variance to distinguish the effects of geographical distances from environmental distances on lizard assemblages. Additionally, to better understand the effects of environmental gradients and forest type on species traits, we used a combination of RLQ and fourth‐corner analysis. Results: Variance in taxonomic distance was mainly explained by a continuous environmental gradient that selects different species. Although we found no evidence of overdispersion or clustering of traits, functional distance was mainly explained by forest type and precipitation. The weak effect of geographical distance on lizard assemblages suggests that different environmental conditions have selected distinct subsets of species and functional traits. Main Conclusions: We showed that the structural heterogeneity along an environmental gradient in Amazonia has a significant impact on the taxonomic and functional composition of lizard assemblages. Environmental filtering along the interfluvial region has caused species turnover and determined differences in the functional characteristics found between assemblages in dense and open forests. These results are relevant for conservation since local species or trait subsets change across the landscape and are therefore irreplaceable in the case of local extinction. [ABSTRACT FROM AUTHOR]

Cross-habitat spillover may be the outcome of a process of habitat loss or degradation where the receiving habitat serves as a refuge for organisms. Once surface habitats are lost or degraded, animals can find underground refuge in caves. This paper is focused on testing whether taxonomic order richness inside caves is positively affected by the loss of the native vegetation cover surrounding caves; whether degradation of native vegetation cover predicts cave community composition; and whether there is a pattern of cave community clusters delimited by similarity in the effects of habitat degradation on animal communities. We gathered a comprehensive speleological dataset consisting of occurrence data of thousands of invertebrates and vertebrates sampled in 864 iron caves in the Amazon, to test the effects of both variables measured inside caves and surrounding landscapes on spatial variation in richness and composition of animal communities. We show that caves can work as refuges for the fauna in landscapes where the native vegetation cover surrounding them was degraded, which was evidenced by landcover change increasing the richness of cave communities and clustering caves by similarity in community composition. Therefore, habitat degradation on the surface should be a key variable when characterizing cave ecosystems for conservation prioritization and offset planning. Habitat degradation causing a cross-habitat spillover effect highlights the importance of maintaining the connection between caves by the surface, especially large caves. Our study can help guide industry and stakeholders working on the complex conciliation between land use and biodiversity conservation. [ABSTRACT FROM AUTHOR]

The classic Wallace's riverine barrier hypothesis (RBH) has been widely invoked to explain species distribution and evolutionary divergence throughout Amazonia. Dispersal and gene flow limited by the inability to cross a river restricts geographic distribution to an interfluvial zone, which causes different assemblage compositions between opposite river banks. In this study, we sampled frogs and Squamata reptiles along the Jari River, a tributary of the lower Amazon River, to test the RBH at assemblage level. We used non-metric multidimensional scaling based on species abundance to compare assemblage composition between river banks. We found that 63.6% of the frogs sampled are absent or occur in low abundances on one of the river banks, which resulted in distinct assemblages between banks. This finding supported the barrier-effect as a predictor of the regional frog diversity, which is remarkable, since the Jari River is considerably narrower than all the Amazonian rivers for which RHB has been supported. However, although some reptile species were restricted to one of the river banks, assemblage composition did not differ between banks. This finding suggests that the barrier-effect should not be extrapolated to other groups of organisms, since good dispersers can homogenize assemblages between river banks. [ABSTRACT FROM AUTHOR]

Biodiversity data, particularly species occurrence and abundance, are indispensable for testing empirical hypothesis in natural sciences. However, datasets built for research programmes do not often meet FAIR (findable, accessible, interoperable and reusable) principles, which raises questions about data quality, accuracy and availability. The 21st century has markedly been a new era for data science and analytics and every effort to aggregate, standardise, filter and share biodiversity data from multiple sources have become increasingly necessary. In this study, we propose a framework for refining and conforming secondary biodiversity data to FAIR standards to make them available for use such as macroecological modelling and other studies. We relied on a Darwin Core base model to standardise and further facilitate the curation and validation of data related including the occurrence and abundance of multiple taxa of a region that encompasses estuarine ecosystems in an ecotonal area bordering the easternmost Amazonia. We further discuss the significance of feeding standardised public data repositories to advance scientific progress and highlight their role in contributing to the biodiversity management and conservation. [ABSTRACT FROM AUTHOR]

Aim: Disentangling historical and ecological effects on different components of species diversity is key to understanding the assembly and maintenance of communities over space and time. Historical factors may be stronger predictors of the community composition at regional scales, while ecological factors may be more important predictors at local scales. Here, we evaluate multiple biodiversity dimensions to investigate riverine barrier and aridity effects on the assembly and structure of lizard assemblages. Location: Semi‐arid region of northeastern Brazil. Taxon: Lacertilia (lizards). Methods: We used data describing 63 lizard assemblages from Caatinga habitats to investigate the effects of a riverine barrier and eight environmental gradients on estimates of taxonomic, phylogenetic and functional diversity. At the regional scale, we compared communities between the banks of the SFr, assuming that differences could emerge from regionally interrupted dispersal in some of the sampled species. At local scales, we evaluated the patterns of phylogenetic and functional structure of the lizard assemblages from Caatinga, and investigated the influence of aridity‐related gradients on species richness, taxonomic, phylogenetic and functional diversity. Results: Lizard assemblages were regionally structured by the SFr acting as a barrier to 47% of the species sampled. We detected phylogenetic signal in 88% of the functional traits. Lizard assemblages were phylogenetic and functionally overdispersed. Moreover, we detected evidence of aridity gradients intensifying the overdispersion of phylogenies and functional traits. Main conclusions: Lizard assemblages showed high variation at both regional and local scales. Riverine barriers played a stronger role as a historical factor structuring assemblages on a regional scale. The interaction of historical constraints with competition enhanced by aridity on a local scale may play a role in structuring lizard assemblages across multiple scales. [ABSTRACT FROM AUTHOR]

Turtles are one of the most threatened groups of vertebrates, with about 60% of species classified at some level of extinction risk. Compounding this extinction crisis are cryptic species and species complexes that are evaluated under a single species epithet but harbor multiple species, each of which needs to be evaluated independently. The Phrynops geoffroanus species group is a classic example. Described first in 1812, it is currently thought to harbor multiple species. To test this hypothesis, we collected mitochondrial and nuclear genomic data, morphometric data, and distribution and associated biome information. We applied statistically rigorous species delimitation analyses, taxonomic hypotheses tests, and fully coalescent phylogenetic reconstruction methods, concluding that the Phrynops geoffroanus species complex comprises four geographically structured species/lineages that diverged during the Pleistocene and are currently geographically structured along the main South American river basins and biomes. These species/lineages show subtle and largely non-significant differences in shape but are characterized by differences in coloration and patterns of marks on the head and plastron. Our results contribute to the understanding of species diversity and diversification of biodiversity in South America and provide an important basis for the conservation of freshwater turtles. [ABSTRACT FROM AUTHOR]

Pesticides have been described as a major cause of bee mortality, and thus are predictors of population decline and decrease in pollination services. Standardized tests with Apis mellifera are already common, and there is a need to create adequate parameters for the native solitary and eusocial species of stingless bees. In this study, we evaluated lethal dosages (LD50 and LD90), lethal time (LT), and sub-lethal effects (SLE) of two pesticides used in soybean crops, abamectin, and acetamiprid, in Scaptotrigona aff. xanthotricha. All tests were performed through contact poisoning. The LD50 and LD90 for acetamiprid were higher than those obtained for abamectin. Survival analysis of S. aff. xanthotricha exposed to LD90 indicated significant differences between pesticides. The LT50 under abamectin (8.25 hours) was significantly lower than acetamiprid (14.25 hours). Considering the PER tests, our results suggest that positive responses to food offerings were reduced by pesticide effects. It was also observed that only the acetamiprid affected the locomotion of the bees. Our results revealed that both pesticides are highly toxic to S. aff. xanthotricha and that acetamiprid was the most toxic for all parameters evaluated. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Tapajós river is among the largest rivers in the world and has been credited as the main affluent of the lower Amazon River. Geomorphological studies in the Tapajós commonly deal with evolutionary, hydrological, and sedimentological issues. Recently, important advances have been made in understanding the morphology and dynamics in the Tapajós, especially in the confluence zone near Santarém, eastern Amazonian Brazil. However, the lack of an independent channel classification system makes it difficult to integrate data obtained from different sources. This work presents a classification system for the lower Tapajós based on morphometric variables extracted from transversal profiles coupled with radar and optical remote sensing data. We used discriminant analysis of principal components for the first time in fluvial geomorphology to provide a clustering-based geomorphological classification, which is statistically supported. We propose a segmentation of the channel into three distinct sections referred to as narrower channel reach, higher ria reach, and lower ria reach. The results showed that the channel has a distinct morphological pattern in each of these reaches, which can also be observed by the variation along the longitudinal profile. Our findings showed that the most variable hydrological and sedimentological patterns are found in the lower ria reach, while the higher ria reach comprises a canyon-shaped, more stable part of the channel. We discuss the implications of this pattern on the ria's evolution. The method developed here could be applied to other areas of the Amazon basin, where the lack of data and logistical difficulties carrying out fieldwork are common obstacles to large-scale investigations. The identified reaches are indended to be considered in the sample design of future works and in the formulation of water resources management strategies. [ABSTRACT FROM AUTHOR]

Comparing reproductive tract morphology between closely-related species may reveal mechanisms and processes leading to reproductive isolation and cladogenesis. Differences in external morphology are often inconspicuous between closely-related Neotropical species, and tissue samples for DNA sequencing are usually scarce for fossorial organisms such as amphisbaenians. Therefore, comparing characters of the reproductive tract between closely related amphisbaenians may be a viable alternative to understand processes by which evolutionary lineages have diverged morphologically from common ancestors. In this study we used multivariate ordination to compare reproductive tract morphology between two closely-related Amphisbaenidae species (Amphisbaena anaemariae and A. silvestrii), which are morphologically similar, and phylogenetically closely related. We tested the hypothesis that interspecific divergence in the reproductive tract may explain mechanisms and processes of reproductive divergence leading to evolutionary divergence. Our results suggest that divergence between two closely related Amphisbaenidae species may be linked with reproductive isolation caused by morphological differences in the reproductive tract. However, the levels of divergence detected varied between sexes and sides of the body on which the variables were measured, with vas deferens length, testis length and diameter and gonad-cloaca length as the determining variables differencing species. Although our findings must be validated by DNA-based analysis, this study provides insights into evolutionary processes based on reproductive divergence mechanisms in organisms for which sampling is hindered by fossoriality. [ABSTRACT FROM AUTHOR]

Copyright of Austral Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Investigating the role of historical and ecological factors structuring assemblages is relevant to understand mechanisms and processes affecting biodiversity across heterogeneous habitats. Considering that community assembly often involves scale-dependent processes, different spatial scales may reveal distinct factors structuring assemblages. In this study we use arboreal and leaf-litter lizard abundance data from 83 plots to investigate assemblage spatial structure at two distinct scales in southwestern Brazilian Amazonia. At a regional scale, we test the general hypothesis that the Madeira River acts as a barrier to dispersal of some lizard species, which results in distinct assemblages between river banks. At a local scale, we test the hypothesis that assemblages are not evenly distributed across heterogeneous habitats but respond to a continuum of inadequate-to-optimal portions of environmental predictors. Our results show that regional lizard assemblages are structured by the upper Madeira River acting as a regional barrier to 29.62% of the species sampled. This finding suggests species have been historically isolated at one of the river banks, or that distinct geomorphological features influence species occurrence at each river bank. At a local scale, different sets of environmental predictors affected assemblage composition between river banks or even along a river bank. These findings indicate that environmental filtering is a major cause of lizard assemblage spatial structure in the upper Madeira River, but predictor variables cannot be generalized over the extensive (nearly 500 km) study area. Based on a single study system we demonstrate that lizard assemblages along the forests near the banks of the upper Madeira River are not randomly structured but respond to multiple factors acting at different and hierarchical spatial scales. [ABSTRACT FROM AUTHOR]

Detecting ecological patterns is highly dependent on the spatial scale of the analysis. However, the importance of scale has been poorly explored when testing environmental influences and estimating niche overlap between animal species. In this study, we tested the hypotheses that: 1) environmental influences on species distribution at different geographic scales will be distinct, 2) niche overlap limits species local occurrence. We modeled ecological distributions of Philodryas argentea (n = 319) and P. georgeboulengeri (n = 61) in the Amazonian biome at different spatial scales: local, using regression analysis along 880 km transect with evenly distributed plots; and broad, modeling occurrence data with a Maximum Entropy algorithm. Variables that contributed to P. argentea occurrence were tree cover and elevation at local scale and annual temperature range for broad scale. For P. georgeboulengeri, the most important variables at local and broad scales were tree cover and elevation, respectively. Niche overlap was estimated at 23% and niches were not similar. We conclude: 1) detection of the most relevant variables for distribution of both species is dependent on spatial scale used; 2) although limited, co-occurrence of species at local scale seems to be allowed by the high niche dissimilarity observed in broad scale. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The genus Scinax is one of the most specious genera of treefrogs of the family Hylidae. Despite the high number of potential new species of Scinax revealed in recent studies, the rate of species descriptions for Amazonia has been low in the last decade. A potential cause of this low rate may be the existence of morphologically cryptic species. Describing new species may not only impact the taxonomy and systematics of a group of organisms but also benefit other fields of biology. Ecological studies conducted in megadiverse regions, such as Amazonia, often meet challenging questions concerning insufficient knowledge of organismal alpha taxonomy. Due to that, detecting specieshabitat associations is dependent on our ability to properly identify species. In this study, we first provide a description of a new species (including its tadpoles) of the genus Scinax distributed along heterogeneous landscapes in southern Amazonia; and secondly assess the influence of environmental heterogeneity on the new species' abundance and distribution. Scinax ruberoculatus sp. nov. differs from all nominal congeners by its small size (SVL 22.6-25.9mmin males and 25.4-27.5mmin females), by having a dark brown spot on the head and scapular region shaped mainly like the moth Copiopteryx semiramis (or a human molar in lateral view, or a triangle), bicolored reddish and grey iris, snout truncate in dorsal view, bilobate vocal sac in males, by its advertisement call consisting of a single pulsed note with duration of 0.134-0.331 s, 10-23 pulses per note, and dominant frequency 1,809-1,895 Hz. Both occurrence and abundance of the new species are significantly influenced by silt content in the soil. This finding brings the first evidence that edaphic factors influence species-habitat association in Amazonian aquatic breeding frogs. [ABSTRACT FROM AUTHOR]

The Brazilian mountain ranges from the Guiana Shield highlands are largely unexplored, with an understudied herpetofauna. Here the amphibian and reptile species diversity of the remote Serra da Mocidade mountain range, located in extreme northern Brazil, is reported upon, and biogeographical affinities and taxonomic highlights are discussed. A 22-days expedition to this mountain range was undertaken during which specimens were sampled at four distinct altitudinal levels (600, 960, 1,060 and 1,365 m above sea level) using six complementary methods. Specimens were identified through an integrated approach that considered morphological, bioacoustical, and molecular analyses. Fifty-one species (23 amphibians and 28 reptiles) were found, a comparable richness to other mountain ranges in the region. The recorded assemblage showed a mixed compositional influence from assemblages typical of other mountain ranges and lowland forest habitats in the region. Most of the taxa occupying the Serra da Mocidade mountain range are typical of the Guiana Shield or widely distributed in the Amazon. Extensions of known distribution ranges and candidate undescribed taxa are also recorded. This is the first herpetofaunal expedition that accessed the higher altitudinal levels of this mountain range, contributing to the basic knowledge of these groups in remote areas. [ABSTRACT FROM AUTHOR]

Knowledge of genetic structure, geographic distance and environmental heterogeneity can be used to identify environmental features and natural history traits that influence dispersal and gene flow. Foraging mode is a trait that might predict dispersal capacity in snakes, because actively foragers typically have greater movement rates than ambush predators. Here, we test the hypothesis that 2 actively foraging snakes have higher levels of gene flow than 2 ambush predators. We evaluated these 4 co-distributed species of snakes in the Brazilian Amazon. Snakes were sampled along an 880 km transect from the central to the southwest of the Amazon basin, which covered a mosaic of vegetation types and seasonal differences in climate. We analyzed thousands of single nucleotide polymorphisms to compare patterns of neutral gene flow based on isolation by geographic distance (IBD) and environmental resistance (IBR). We show that IBD and IBR were only evident in ambush predators, implying lower levels of dispersal than the active foragers. Therefore, gene flow was high enough in the active foragers analyzed here to prevent any build-up of spatial genotypic structure with respect to geographic distance and environmental heterogeneity. [ABSTRACT FROM AUTHOR]

The article focuses on new findings about Atractus riveroi, a rarely sampled snake species from the Amazonian highlands in Brazil. Topics discussed include its extended geographic range, variations in body color and morphology, and the significance of these findings for understanding species diversity and conservation.

Rising habitat loss is one of the main drivers of the global amphibian decline. Nevertheless, knowledge of amphibian diversity needed for effective habitat protection is still highly inadequate in remote tropical regions, the greater part of the Amazonia. In this study we integrated molecular, morphological and bioacoustic evidence to evaluate the species richness of the treefrogs genus Scinax over a 1000 km transect across rainforest of the Purus-Madeira interfluve, and along the east bank of the upper Madeira river, Brazilian Amazonia. Analysis revealed that 82% of the regional species richness of Scinax is still undescribed; two nominal species, seven confirmed candidate species, two unconfirmed candidate species, and one deep conspecific lineage were detected in the study area. DNA barcoding based analysis of the 16s rRNA gene indicates possible existence of three discrete species groups within the genus Scinax, in addition to the already-known S. rostratus species Group. Quantifying and characterizing the number of undescribed Scinax taxa on a regional scale, we provide a framework for future taxonomic study in Amazonia. These findings indicate that the level to which Amazonian anura species richness has been underestimated is far greater than expected. Consequently, special attention should be paid both to taxonomic studies and protection of the still-neglected Amazonian Scinax treefrogs. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Studies leading to decision-making for environmental licensing often fail to provide accurate estimates of diversity. Measures of snake diversity are regularly obtained to assess development impacts in the rainforests of the Amazon Basin, but this taxonomic group may be subject to poor detection probabilities. Recently, the Brazilian government tried to standardize sampling designs by the implementation of a system (RAPELD) to quantify biological diversity using spatially-standardized sampling units. Consistency in sampling design allows the detection probabilities to be compared among taxa, and sampling effort and associated cost to be evaluated. The cost effectiveness of detecting snakes has received no attention in Amazonia. Here we tested the effects of reducing sampling effort on estimates of species densities and assemblage composition. We identified snakes in seven plot systems, each standardised with 14 plots. The 250 m long centre line of each plot followed an altitudinal contour. Surveys were repeated four times in each plot and detection probabilities were estimated for the 41 species encountered. Reducing the number of observations, or the size of the sampling modules, caused significant loss of information on species densities and local patterns of variation in assemblage composition. We estimated the cost to find a snake as $ 120 U.S., but general linear models indicated the possibility of identifying differences in assemblage composition for half the overall survey costs. Decisions to reduce sampling effort depend on the importance of lost information to target-issues, and may not be the preferred option if there is the potential for identifying individual snake species requiring specific conservation actions. However, in most studies of human disturbance on species assemblages, it is likely to be more cost-effective to focus on other groups of organisms with higher detection probabilities. [ABSTRACT FROM AUTHOR]

The article presents study on geographic range, hemipenial characteristics and morphology of toad-headed Pitviper Bothrocophias hyoprora (B. hyoprora) in Brazil. It mentions the measurement of snout-vent length (SVL) and tail length (TL), preparation of the right hemipenis from a preserved specimen and Karyotype analysis of the species. It adds general hemipenial morphology of B. hyoprora is consistent with all Crotalinae.

The authors discuss the results of their study on the influence of ecological factors on the species composition of snakes in the Reserva Ducke in Manaus, Amazonas, Brazil. There was no correlation found between the distance from the stream and the total number of species recorded in all riparian plots. Species composition was correlated with litter depth but not with the slope of terrain and clay percentage in the soil. The study also found that stochastic processes, geographical distances and historical influences do not affect species turnover but environmental conditions do.