Search

Abstract Background Detailed knowledge of every possible manifestation of Internal Carotid Artery (ICA) disease is important. For improving detection and a timely adoption of secondary prevention procedures or treatments. Transient oculomotor nerve palsies have been described associated with stenosis or occlusion of the ICA. Case presentation We described a patient that develop a sequential combination of transient monocular loss of vision followed by binocular diplopia secondary to an unstable atherosclerotic preocclusive stenosis of an internal carotid artery previously treated with radiotherapy. Conclusions The peculiar sequence of transient monocular vision that give rise later into a transient binocular diplopia (double or nothing) should be kept in mind as a possible manifestation of critical stenosis of ICA.

Urbanization is resulting in habitat loss and fragmentation around the world, but its effects on biodiversity remain poorly understood. We investigated how the increase of urban cover surrounding nine Brazilian Atlantic forest reserves (14 ha - 1058 ha) affects the taxonomic, functional and phylogenetic diversity of bird communities, considering forest and non-forest species separately. Using a multi-scale local landscape approach, we estimated the percentage of urban cover in circular buffers of varying radii (200–1000 m). We calculated 10 complementary metrics of bird diversity and modelled them against the percentage of urban cover using generalized additive models. Urbanization had a negative, non-linear impact on the taxonomic diversity of bird communities, with a sharp decrease of up to 50 % in the effective number of rare, typical and dominant species in landscapes with 20–40 % of urbanization. This decrease was not restricted to forest species (urban avoiders), but also affected non-forest ones (urban utilizers and dwellers). The impact of urbanization on functional and phylogenetic diversity were less evident, suggesting that the vulnerability to urbanization has a weak phylogenetic and phenotypic signal. We conclude that urbanization impacts a broad spectrum of bird clades and traits and drastically reduce the taxonomic diversity of bird communities.

Global herpetofauna faces threats by habitat loss and degradation, with amphibian and reptile species maintenance in human-modified landscapes not only depending on forest remnants, but also on biodiversity-friendly matrices, such as agroforestry systems. Nevertheless, herpetological studies in agroforests are limited, hindering conservation decisions. To fill this gap, we conducted a global meta-analysis to assess the ability of agroforestry systems to maintain abundance and richness of amphibian and reptile species when compared to native forests. We analyze how community parameters (richness or abundance) and agroforest types based on the vegetation characteristics described by the studies (simplified or complex) impact the variation of overall effect size. We also used meta-regression models to examine how the amount of forest cover around agroforests affects the effect size. Finally, we calculated Sorensen's Index based on incidence data to investigate the degree of similarity in species composition of amphibians and reptiles between agroforestry systems and native forests. Our results showed that amphibian diversity in agroforests is lower than in native forests, regardless of the parameter and agroforestry type. For reptiles, agroforests showed higher abundance and similar species richness to forests. Simplified agroforestry systems support less reptile diversity than complex systems, which are more similar to forests. Interestingly, landscape forest amount modulates the ability of agroforests in maintain reptile richness. In fact, agroforests inserted in highly forested landscapes can harbor higher richness of reptiles than forests. We also found that half of the amphibian and reptile species observed in agroforests are different from those observed in native forests. Our findings highlights that agroforests cannot replace native forests because such systems harbor reduced abundance and species richness, especially amphibians, and a distinct species composition. However, when inserted in forested landscapes these agricultural systems can host rich reptile communities. Thus, preserving native forests and restoring deforested regions are crucial for herpetofauna conservation in human-modified landscapes.

Abstract Human activity has diminished forests in different terrestrial ecosystems. This is well illustrated in the Brazilian Atlantic Forest, which still hosts high levels of species richness and endemism, even with only 28% of its original extent remaining. The consequences of such forest loss in remaining populations can be investigated with several approaches, including the genomic perspective, which allows a broader understanding of how human disturbance influences the genetic variability in natural populations. In this context, our study investigated the genomic responses of Euterpe edulis Martius, an endangered palm tree, in forest remnants located in landscapes presenting different forest cover amount and composed by distinct bird assemblage that disperse its seeds. We sampled 22 areas of the Brazilian Atlantic Forest in four regions using SNP markers inserted into transcribed regions of the genome of E. edulis, distinguishing neutral loci from those putatively under natural selection (outlier). We demonstrate that populations show patterns of structure and genetic variability that differ between regions, as a possible reflection of deforestation and biogeographic histories. Deforested landscapes still maintain high neutral genetic diversity due to gene flow over short distances. Overall, we not only support previous evidence with microsatellite markers, but also show that deforestation can influence the genetic variability outlier, in the scenario of selective pressures imposed by these stressful environments. Based on our findings, we suggest that, to protect genetic diversity in the long term, it is necessary to reforest and enrich deforested areas, using seeds from populations in the same management target region.

Vertebrate frugivores play important ecological roles. Here, the authors analyse a global dataset on plants and birds and find that plant-frugivore networks are more dissimilar, yet structurally consistent, across ecoregion and biome boundaries.

Understanding how biological communities respond to human-caused landscape disturbances is urgently needed to identify optimal spatial scenarios for preserving biodiversity in anthropogenic landscapes. Forest loss is increasingly cited as a major disturbance in these landscapes, but its impact on biodiversity in mountain regions with high endemism is not well understood. Here we evaluated how bird species diversity responds to forest loss in ‘La Montaña’ mountain region of Guerrero State, Mexico. We separately assessed the complete bird assemblage, and the diversity and spatial distribution of three different ecological groups (forest-specialists, habitat-generalists, and disturbance-adapted species) in the whole landscape mosaic. We found that the diversity of the complete assemblage decreased linearly with forest loss. However, species responses to forest loss differed among ecological groups, with the diversity of forest-specialist and habitat-generalist species increasing in more forested landscapes, and the diversity of disturbance-adapted species following the opposite pattern. Similarly, the proportion of sites occupied by forest-specialist birds decreased with forest loss, but site occupancy by habitat-generalist and disturbance-adapted birds was independent from forest cover. Our findings highlight that the optimal landscape scenarios for preserving bird biodiversity in general and forest species in particular, are those that maintain as much forest cover as possible.

Abstract Interspecific interactions are a major determinant of stability in ecological communities and are known to vary with biotic and abiotic conditions. Deforestation is the primary driver of the ongoing sixth mass extinction, yet its effect on species interactions remains largely unexplored. We investigate how deforestation affects species interactions using a complex systems model and a co‐occurrence dataset of 363 bird species, observed across 134 sites, from 5 regions across the Brazilian Atlantic Forest totalling 27,226 interactions. Both theoretical and empirical results show that interspecific interactions vary non‐monotonically with forest cover and are more positive than average in areas with higher forest cover, and to a lesser extent in highly deforested areas. Observed differences in interactions reflect both species turnover and changes in pairwise interactions. Our results point to changes in stability across the gradient of deforestation that may lead to varying community resilience to environmental perturbations. Key Interdisciplinary Aspects Species interactions are expected to vary due to the biological, chemical and physical changes caused by deforestation on their local environment. We use a mathematical complex systems approach, as well as ecological data, to show that species interactions are more positive in highly forested areas. We propose that the alteration of species interactions caused by deforestation will affect the stability of communities and their resilience to future perturbations (e.g. climate change).

Biodiversity is already experiencing the effects of climate change through range expansion, retraction, or relocation, potentializing negative effects of other threats. Future projections already indicate richness reduction and composition modifications of bird communities due to global warming, which may disrupt the provision of key ecological services to ecosystem maintenance. Here, we systematically review the effect of morphological, ecological, and geographical traits on the amount of future suitable area for birds worldwide. Specifically, we tested whether body mass, diet, habitat type, movement pattern, range size, and biogeographic realm affect birds' suitable area. Our search returned 75 studies that modeled the effects of climate change on 1,991 bird species. Our analyses included 1,661 species belonging to 128 families, representing 83% of the total, for which we were able to acquire all the six traits. The proportion of birds' suitable area was affected by range size, body mass, habitat type, and biogeographic realm, while diet and movement pattern showed lower relative importance and were not included in our final model. Contrary to expectations, the proportion of birds' suitable area was negatively related to range size, which may be explained by higher climatic stability predicted in certain areas that harbor species with restricted distribution. In contrast, we observed that birds presenting higher body mass will show an increase of the proportion of suitable area in the future. This is expected due to the high exposure of smaller birds to environmental changes and their difficulty to keep thermoregulation. Our results also indicated a low proportion of suitable area to forest-dependent birds, which is in accordance with their higher vulnerability due to specific requirements for reproduction and feeding. Finally, the proportion of suitable area was low for birds from Oceania, which is expected since the region encompasses small islands isolated from continents, preventing their species from reaching new suitable areas. Our study highlights that different traits should be considered when assessing extinction risk of species based on future projections, helping to improve bird conservation, especially the most vulnerable to climate change.

Global biodiversity is threatened by land-use changes through human activities. This is mainly due to the conversion of continuous forests into forest fragments surrounded by anthropogenic matrices. In general, sensitive species are lost while species adapted to disturbances succeed in altered environments. However, whether the interactions performed by the persisting species are also modified, and how it scales up to the network level throughout the landscape are virtually unknown in most tropical hotspots of biodiversity. Here we evaluated how landscape predictors (forest cover, total core area, edge density, inter-patch isolation) and local characteristics (fruit availability, vegetation complexity) affected understory birds seed-dispersal networks in 19 forest fragments along the hyperdiverse but highly depauperate northeast distribution of the Brazilian Atlantic Forest. Also, our sampled sites were distributed in two regions with contrasting land cover changes. We used mist nets to obtain samples of understory bird food contents to identify the plant species consumed and dispersed by them. We estimated network complexity on the basis of the number of interactions, links per species, interaction evenness, and modularity. Our findings showed that the number of interactions increased with the amount of forest cover, and it was significantly lower in the more deforested region. None of the other evaluated parameters were affected by any other landscape or local predictors. We also observed a lack of significant network structure compared to null models, which we attribute to a pervasive impoverishment of bird and plant communities in these highly modified landscapes. Our results demonstrate the importance of forest cover not only to maintain species diversity but also their respective mutualistic relationships, which are the bases for ecosystem functionality, forest regeneration and the provision of ecological services.

Habitat loss is the dominant threat to biodiversity and ecosystem functioning in terrestrial environments. In this study, we used an a priori classification of bird species based on their dependence on native forest habitats (forest-specialist and habitat generalists) and specific food resources (frugivores and insectivores) to evaluate their responses to forest cover reduction in landscapes in the Brazilian Atlantic Forest. From the patch-landscapes approach, we delimited 40 forest sites, and quantified the percentage of native forest within a 2 km radius around the center of each site (from 6 - 85%). At each site, we sampled birds using the point-count method. We used a null model, a generalized linear model and a four-parameter logistic model to evaluate the relationship between richness and abundance of the bird groups and the native forest amount. A piecewise model was then used to determine the threshold value for bird groups that showed nonlinear responses. The richness and abundance of the bird community as a whole were not affected by changes in forest cover in this region. However, a decrease in forest cover had a negative effect on diversity of forest-specialist, frugivorous and insectivorous birds, and a positive effect on generalist birds. The species richness and abundance of all ecological groups were nonlinearly related to forest reduction and showed similar threshold values, i.e., there were abrupt changes in individuals and species numbers when forest amount was less than approximately 50%. Forest sites within landscapes with forest cover that was less than 50% contained a different bird species composition than more extensively forested sites and had fewer forest-specialist species and higher beta-diversity. Our study demonstrated the pervasive effect of forest reduction on bird communities in one of the most important hotspots for bird conservation and shows that many vulnerable species require extensive forest cover to persist.