Fatores determinantes da distribuição de aves no interflúvio Purus-Madeira

Studies addressing deterministic and stochastic processes that effect changes in species composition among sites (beta diversity) have focused, for the most part, on sessile organisms. These are highly susceptible to random dispersal processes, confirming neutral theory assumptions. At first glance, birds would appear to have high dispersal ability. However, in Amazonian forests most birds are extremely sedentary, with restricted distributions, often limited by large rivers. In this study, we evaluated the environmental effects (palm species composition) relative to geographical distances between sites, as factors related differences in forest bird species composition. We sampled 11 sites in upland forest, separated from one another by 60 km, covering a 670 km extension in the Purus-Madeira interfluve of Western Amazon, Brazil. Similarity in bird assemblage was significantly correlated with palm species composition. Understory and canopy birds assemblages showed similar correlation with palm species composition. When the effect of palm species composition was controlled, distance was not a good indicator of changes in the bird community. Our results suggest that, in this region and at this spatial scale, birds are not limited by geographical distance and can disperse throughout the region studied. Nevertheless, they are not uniformly distributed which can best be explained by environmental variation, represented here by palm species composition. Although our results indicate that geographic distance has no effect on changes in bird composition, we emphasize that studies on a larger spatial scale could help to understand dispersal limitation effects in tropical Amazonian forest bird composition.Até o presente, estudos abordando fatores determinísticos e estocásticos que afetam mudanças na composição de espécies entre locais enfocaram, em geral, organismos sésseis. Esses organismos são especialmente suscetíveis a processos aleatórios de dispersão, corroborando premissas da teoria neutra. As aves, aparentemente, apresentam boa capacidade de dispersão. No entanto, em florestas amazônicas, muitas espécies de aves são extremamente sedentárias e apresentam distribuição restrita, tipicamente limitada por grandes rios. Neste estudo avaliamos a importância de efeitos ambientais, medidos pela composição de espécies de palmeiras, relativos aos efeitos da distância geográfica, como fatores geradores de diferenças na composição de aves amazônicas. Nós amostramos 11 localidades em uma floresta de terra firme, distantes aproximadamente 60 km entre si, cobrindo uma extensão de 670 km, no interflúvio Purus-Madeira, Amazônia brasileira. A similaridade das assembleias de aves foi significativamente correlacionada com a composição de palmeiras. Aves de sub-bosque e aves de dossel, analisadas separadamente, também apresentaram forte correlação com a composição de palmeiras. Com o efeito ambiental controlado, a distância geográfica não foi um bom indicador de mudanças na avifauna na área de estudo, não explicando a ocorrência de espécies de nenhum dos grupos de aves. Os resultados sugerem que, na escala espacial e na região deste estudo, as aves não são limitadas pela distância geográfica entre as localidades, podendo se dispersar por toda extensão da área estudada. No entanto, a composição de aves muda entre as localidades amostradas e essas mudanças podem ser melhor explicadas pela variação ambiental, representada pela composição de palmeiras. Embora nossos resultados indiquem que a distância geográfica não tenha efeito sobre as mudanças na composição de aves, enfatizamos que estudos em uma escala maior poderão ajudar a entender os efeitos da limitação de dispersão sobre a composição de aves florestais amazônicas

Genetic diversity and spatial structure of the Rufous-throated Antbird (Gymnopithys rufigula), an Amazonian obligate army-ant follower

Amazonian understory antbirds are thought to be relatively sedentary and to have limited dispersal ability; they avoid crossing forest gaps, and even narrow roads through a forest may limit their territories. However, most evidence for sedentariness in antbirds comes from field observations and plot-based recapture of adult individuals, which do not provide evidence for lack of genetic dispersal, as this often occurs through juveniles. In this study, we used microsatellite markers and mitochondrial control-region sequences to investigate contemporary and infer historical patterns of genetic diversity and structure of the Rufous-throated Antbird (Gymnopithys rufigula) within and between two large reserves in central Amazonia. Analyses based on microsatellites suggested two genetically distinct populations and asymmetrical gene flow between them. Within a population, we found a lack of genetic spatial autocorrelation, suggesting that genotypes are randomly distributed and that G. rufigula may disperse longer distances than expected for antbirds. Analyses based on mitochondrial sequences did not recover two clear genetic clusters corresponding to the two reserves and indicated the whole population of the Rufous-throated Antbird in the region has been expanding over the last 50,000 years. Historical migration rates were low and symmetrical between the two reserves, but we found evidence for a recent unilateral increase in gene flow. Recent differentiation between individuals of the two reserves and a unilateral increase in gene flow suggest that recent urban expansion and habitat loss may be driving changes and threatening populations of Rufous-throated Antbird in central Amazonia. As ecological traits and behavioral characteristics affect patterns of gene flow, comparative studies of other species with different behavior and ecological requirements will be necessary to better understand patterns of genetic dispersal and effects of urban expansion on Amazonian understory antbirds. © 2017 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd

The role of environmental filtering, geographic distance and dispersal barriers in shaping the turnover of plant and animal species in Amazonia

To determine the effect of rivers, environmental conditions, and isolation by distance on the distribution of species in Amazonia. Location: Brazilian Amazonia. Time period: Current. Major taxa studied: Birds, fishes, bats, ants, termites, butterflies, ferns + lycophytes, gingers and palms. We compiled a unique dataset of biotic and abiotic information from 822 plots spread over the Brazilian Amazon. We evaluated the effects of environment, geographic distance and dispersal barriers (rivers) on assemblage composition of animal and plant taxa using multivariate techniques and distance- and raw-data-based regression approaches. Environmental variables (soil/water), geographic distance, and rivers were associated with the distribution of most taxa. The wide and relatively old Amazon River tended to determine differences in community composition for most biological groups. Despite this association, environment and geographic distance were generally more important than rivers in explaining the changes in species composition. The results from multi-taxa comparisons suggest that variation in community composition in Amazonia reflects both dispersal limitation (isolation by distance or by large rivers) and the adaptation of species to local environmental conditions. Larger and older river barriers influenced the distribution of species. However, in general this effect is weaker than the effects of environmental gradients or geographical distance at broad scales in Amazonia, but the relative importance of each of these processes varies among biological groups

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

FIP Convergence Matrix 2022-2050

This Research Object contains a Convergence Matrix for FIPs created any time in 2022, ending any time until December 31st 2050