Changes in biodiversity may impact infectious disease transmission through multiple mechanisms. We explored the impact of biodiversity changes on the transmission of Amazonian leishmaniases, a group ...of wild zoonoses transmitted by phlebotomine sand flies (Psychodidae), which represent an important health burden in a region where biodiversity is both rich and threatened. Using molecular analyses of sand fly pools and blood‐fed dipterans, we characterized the disease system in forest sites in French Guiana undergoing different levels of human‐induced disturbance. We show that the prevalence of Leishmania parasites in sand flies correlates positively with the relative abundance of mammal species known as Leishmania reservoirs. In addition, Leishmania reservoirs tend to dominate in less diverse mammal communities, in accordance with the dilution effect hypothesis. This results in a negative relationship between Leishmania prevalence and mammal diversity. On the other hand, higher mammal diversity is associated with higher sand fly density, possibly because more diverse mammal communities harbor higher biomass and more abundant feeding resources for sand flies, although more research is needed to identify the factors that shape sand fly communities. As a consequence of these antagonistic effects, decreased mammal diversity comes with an increase of parasite prevalence in sand flies, but has no detectable impact on the density of infected sand flies. These results represent additional evidence that biodiversity changes may simultaneously dilute and amplify vector‐borne disease transmission through different mechanisms that need to be better understood before drawing generalities on the biodiversity‐disease relationship.
see also the Perspective by Taal Levi and Aimee L. Massey
Fruit bats provide valuable pollination services to humans through a unique coevolutionary relationship with chiropterophilous plants. However, chiropterophily in the Old World and the pollination ...roles of large bats, such as flying foxes (Pteropus spp., Acerodon spp., Desmalopex spp.), are still poorly understood and require further elucidation. Efforts to protect these bats have been hampered by a lack of basic quantitative information on their role as ecosystem service providers. Here, we investigate the role of the locally endangered island flying fox Pteropus hypomelanus in the pollination ecology of durian (Durio zibethinus), an economically important crop in Southeast Asia. On Tioman Island, Peninsular Malaysia, we deployed 19 stations of paired infrared camera and video traps across varying heights at four individual flowering trees in a durian orchard. We detected at least nine species of animal visitors, but only bats had mutualistic interactions with durian flowers. There was a clear vertical stratification in the feeding niches of flying foxes and nectar bats, with flying foxes feeding at greater heights in the trees. Flying foxes had a positive effect on mature fruit set and therefore serve as important pollinators for durian trees. As such, semi‐wild durian trees—particularly tall ones—may be dependent on flying foxes for enhancing reproductive success. Our study is the first to quantify the role of flying foxes in durian pollination, demonstrating that these giant fruit bats may have far more important ecological, evolutionary, and economic roles than previously thought. This has important implications and can aid efforts to promote flying fox conservation, especially in Southeast Asian countries.
Camera‐trapping shows that flying foxes (Pteropus hypomelanus) contribute to reproductive success of the durian (Durio zibethinus) tree. This new evidence of chiropterophily in the Palaeotropics shows how large fruit bats can also play a role in the production of economically important fruit.
Summary
Frugivory in tropical forests is a major ecological process as most tree species rely on frugivores to disperse their seeds. However, the underlying mechanisms driving frugivore–plant ...networks remain understudied. Here, we evaluate the data available on the Afrotropical frugivory network to identify structural properties, as well as assess knowledge gaps.
We assembled a database of frugivory interactions from the literature with > 10 000 links, between 807 tree and 285 frugivore species. We analysed the network structure using a block model that groups species with similar interaction patterns and estimates interaction probabilities among them. We investigated the species traits related to this grouping structure.
This frugivory network was simplified into 14 tree and 14 frugivore blocks. The block structure depended on the sampling effort among species: Large mammals were better‐studied, while smaller frugivores were the least studied. Species traits related to frugivory were strong predictors of the species composition of blocks and interactions among them. Fruits from larger trees were consumed by most frugivores, and large frugivores had higher probabilities to consume larger fruits.
To conclude, this large‐scale frugivory network was mainly structured by species traits involved in frugivory, and as expected by the distribution areas of species, while still being limited by sampling incompleteness.
Tropical rain forests worldwide are under increasing pressure from human activities, which are altering key ecosystem processes such as plant–animal interactions. However, while the direct impact of ...anthropogenic disturbance on animal communities has been well studied, the consequences of such defaunation for mutualistic interactions such as seed dispersal remains chiefly understood at the plant species level. We asked whether communities of endozoochorous tree species had altered seed removal in forests affected by hunting and logging and if this could be related to modifications of the frugivore community. At two contrasting forest sites in French Guiana, Nouragues (protected) and Montagne de Kaw (hunted and partly logged), we focused on four families of animal-dispersed trees (Sapotaceae, Myristicaceae, Burseraceae, and Fabaceae), which represent 88% of all endozoochorous trees that were fruiting at the time and location of the study. We assessed the abundance of the seed dispersers and predators of these four focal families by conducting diurnal distance sampling along line transects. Densities of several key seed dispersers such as large-bodied primates were greatly reduced at Montagne de Kaw, where the specialist frugivore Ateles paniscus is probably extinct. In parallel, we estimated seed removal rates from fruit and seed counts conducted in 1-m2 quadrats placed on the ground beneath fruiting trees. Seed removal rates dropped from 77% at Nouragues to 47 % at Montagne de Kaw, confirming that the loss of frugivores associated with human disturbance impacts seed removal at the community level. In contrast to Sapotaceae, whose seeds are dispersed by mammals only, weaker declines in seed removal for Burseraceae and Myristicaceae suggest that some compensation may occur for these bird- and mammal-dispersed families, possibly because of the high abundance of Toucans at the disturbed site. The defaunation process currently occurring across many tropical forests could dramatically reduce the diversity of entire communities of animal-dispersed trees through seed removal limitation.
Ecology Letters (2011) 14: 34–41
Negative density dependence (NDD) and environmental filtering (EF) shape community assembly, but their relative importance is poorly understood. Recent studies have ...shown that seedling’s mortality risk is positively related to the phylogenetic relatedness of neighbours. However, natural enemies, whose depredations often cause NDD, respond to functional traits of hosts rather than phylogenetic relatedness per se. To understand the roles of NDD and EF in community assembly, we assessed the effects on seedling mortality of functional similarity, phylogenetic relatedness and stem density of neighbouring seedlings and adults in a species‐rich tropical forest. Mortality risks increased for common species when their functional traits departed substantially from the neighbourhood mean, and for all species when surrounded by close relatives. This indicates that NDD affects community assembly more broadly than does EF, and leads to the tentative conclusion that natural enemies respond to phylogenetically correlated traits. Our results affirm the prominence of NDD in structuring species‐rich communities.
Larger animals are assumed to ingest larger seeds and consume larger fruits, but empirical studies reveal inconsistent trends between body mass and the average size of fruits and seeds ingested. ...Furthermore, no studies have explored seed size relationships with morphological traits, such as skull dimensions. Such characteristics might provide more reliable estimates of ingestion ability and allow for accurate predictions of seed dispersal capacity in species for which we lack empirical data, especially extinct species. To determine whether (i) mammalian skull dimensions are better predictors of the maximum size of ingested seeds and fruits, compared to body mass and (ii) body mass are the better predictors of mean fruit and seed sizes, we studied these relationships across three mammalian orders: Chiroptera, Primates and Carnivora.
We collected novel data on skull dimensions and collated available data on body mass and maximum and mean sizes of ingested fruits and seeds for mammals (N = 100) across the Neotropics, Asia, Africa and Madagascar. We explored the relationships between anatomical traits and fruit and seed sizes of extant species and made predictions for five extinct species.
Our results revealed that body mass and skull dimensions are essential determinants of ingested fruit and seed size in mammals. The latter traits can generate predictions for extinct species, especially coronoid height and maximum jaw gape. Nevertheless, body mass predicted larger ingested fruits and seeds than skull dimensions and explained a greater part of the variance for both maximum and mean sizes in our dataset.
Our results show how body mass and cranial anatomy constrain seed size and reinforce the importance of maintaining functional diversity in seed dispersers to maintain tropical forest structure. We also show that scientists can use morphological characteristics to predict the seed dispersal potential of extinct mammals allowing better inferences on past and future consequences of frugivore extinctions within tropical forests.
Read the free Plain Language Summary for this article on the Journal blog.
Read the free Plain Language Summary for this article on the Journal blog.
Animal-mediated seed dispersal is important for sustaining biological diversity in forest ecosystems, particularly in the tropics. Forest fragmentation, hunting, and selective logging modify forests ...in myriad ways and their effects on animal-mediated seed dispersal have been examined in many case studies. However, the overall effects of different types of human disturbance on animal-mediated seed dispersal are still unknown. We identified 35 articles that provided 83 comparisons of animal-mediated seed dispersal between disturbed and undisturbed forests; all comparisons except one were conducted in tropical or subtropical ecosystems. We assessed the effects of forest fragmentation, hunting, and selective logging on seed dispersal of fleshy-fruited tree species. We carried out a meta-analysis to test whether forest fragmentation, hunting, and selective logging affected 3 components of animal-mediated seed dispersal: frugivore visitation rate, number of seeds removed, and distance of seed dispersal. Forest fragmentation, hunting, and selective logging did not affect visitation rate and were marginally associated with a reduction in seed-dispersal distance. Hunting and selective logging, but not fragmentation, were associated with a large reduction in the number of seeds removed. Fewer seeds of large-seeded than of small-seeded tree species were removed in hunted or selectively logged forests. A plausible explanation for the consistently negative effects of hunting and selective logging on large-seeded plant species is that large frugivores, as the predominant seed dispersers for large-seeded plant species, are the first animals to be extirpated from hunted or logged forests. The reduction in forest area after fragmentation appeared to have weaker effects on frugivore communities and animal-mediated seed dispersal than hunting and selective logging. The differential effects of hunting and selective logging on large-and small-seeded tree species underpinned case studies that showed disrupted plant-frugivore interactions could trigger a homogenization of seed traits in tree communities in hunted or logged tropical forests. La dispersión de semillas por animales es importante para sustentar la diversidad biológica en ecosistemas forestales, particularmente en los trópicos. La fragmentación de bosques, la cacería y la tala selectiva modifican los bosques de muchas maneras y sus efectos sobre la dispersión de semillas por animales han sido examinados en muchos estudios de caso. Sin embargo, todavía se desconocen los efectos generales de los diferentes tipos de perturbación humana sobre la dispersión de semillas por animales. Identificamos 35 artículos que proporcionaron 83 comparaciones de dispersión de semillas por animales entre bosques perturbados y no perturbados; todas las comparaciones excepto una fueron en bosques tropicales o subtropicales. Evaluamos los efectos de la fragmentación del bosque, la cacería y la tala selectiva sobre la dispersión de especies de árboles con frutos carnosos. Efectuamos un meta análisis para probar si la fragmentación del bosque, la cacería y la tala selectiva afectaban a tres componentes de la dispersión de semillas por animales: tasa de visitación de frugívoros, números de semillas removidas y distancia de dispersión de semillas. La fragmentación del bosque, la cacería y la tala selectiva no afectaron la tasa de visitación y estuvieron marginalmente asociadas con la disminución de la distancia de dispersión. La cacería y la tala selectiva, pero no la fragmentación, se asociaron con una reducción importante en el número de semillas removidas. Menos semillas de especies de árboles con semillas grandes que de semillas pequeñas fueron removidas en bosques con cacería o tala selectiva. Una explicación plausible de los efectos consistentemente negativos de la cacería y la tala selectiva sobre las especies con semillas grandes es que los frugívoros grandes, como los dispersores predominantes de especies de plantas con semillas grandes, son los primeros animales extirpados de bosques con cacería o tala. La reducción de la superficie de bosque después de la fragmentación pareció tener efectos más débiles sobre las comunidades de frugívoros y la dispersión de semillas por animales que la cacería y la tala selectiva. Los efectos diferenciales de la cacería y la tala selectiva sobre especies de árboles con semillas grandes y pequeñas sustentaron estudios de caso que mostraron que la alteración de interacciones planta-frugívoro podría detonar la homogenización de atributos de las semillas en comunidades de árboles en bosques tropicales con cacería o tala.
Arboreal and flying frugivorous animals represent primary dispersers in the Neotropics. Studies suggest a possible compensation for the loss of large species by smaller ones with expanding rampant ...anthropogenic pressures and declining populations of larger frugivores. However, studies on seed dispersal by frugivores vertebrates generally focus on the diurnal, terrestrial, canopy, and flying species, with the nocturnal canopy ones being less studied. Setting camera traps high in the canopy of fruiting nutmeg trees revealed for the first time the high frequency of the kinkajou (Potos flavus, Schreber, 1774, Procyonidae), an overlooked nocturnal frugivore species (Order Carnivora) in the Guianas. The diversity of the fruit species consumed by the kinkajou calls for considering it as an important seed disperser. The overlap of the size of seeds dispersed by frugivores observed in nutmeg trees suggests that the small (2-5 kg) kinkajou may compensate for the loss of large (5-10 kg) frugivorous vertebrates in the canopy. Camera traps visualise how the kinkajou is adapted to forage in the nutmeg tree crown and grab the fruit. Such information is vital for conservation because compensation of seed dispersal by small frugivores is crucial in increasing anthropogenic stressors.
Current issues in tropical phenology Abernethy, Katharine; Bush, Emma R.; Forget, Pierre-Michel ...
Biotropica,
05/2018, Letnik:
50, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We retrace the development of tropical phenology research, compare temperate phenology study to that in the tropics and highlight the advances currently being made in this flourishing discipline. The ...synthesis draws attention to how fundamentally different tropical phenology data can be to temperate data. Tropical plants lack a phase of winter dormancy and may grow and reproduce continually. Seasonal patterns in environmental parameters, such as rainfall, irradiance or temperature, do not necessarily coincide temporally, as they do in temperate climes. We review recent research on the drivers of phenophase cycles in individual trees, species and communities and highlight how significant innovations in biometric tools and approaches are being driven by the need to deal with circular data, the complexity of defining tropical seasons and the myriad growth and reproductive strategies used by tropical plants. We discuss how important the use of leaf phenology (or remotely-sensed proxies of leaf phenophases) has become in tracking biome responses to climate change at the continental level and how important the phenophase of forests can be in determining local weather conditions. We also highlight how powerful analyses of plant responses are hampered at many tropical sites by a lack of contextual data on local environmental conditions. We conclude by arguing that there is a clear global benefit in increasing long term tropical phenology data collection and improving empirical collection of local climate measures, contemporary to the phenology data. Directing more resources to research in this sector will be widely beneficial.
Arboreal camera trapping is a burgeoning method providing a novel and effective technique to answer research questions across a variety of ecosystems, and it has the capacity to improve our ...understanding of a wide range of taxa. However, while terrestrial camera trapping has received much attention, there is little guidance for dealing with the unique challenges of working in the arboreal realm.
Our review draws on the expertise of researchers from six continents and the broader literature to investigate the advantages and disadvantages of arboreal camera trapping, and challenges to consider when using this technology. We also include mini‐guides with detailed information on the current arboreal camera trap literature, mounts used to install arboreal cameras, tree climbing pointers and safety tips, methods for deploying cameras without climbing, and tips for managing interference with camera function.
We find that arboreal camera traps have been most commonly used in the study of mammals in forests; however, there is potential for this method to be applied to a broad range of habitats including urban areas, and taxa such as birds, amphibians, invertebrates, and plants. Methods in arboreal camera trapping could be improved by developing a greater understanding of the factors affecting detection of species. The most common challenges of arboreal camera trapping are camera placement and camera site access. These can be overcome by understanding correct camera orientation, managing potential sources of interference in front of cameras, utilizing appropriate cameras mounts and training researchers properly.
Given the benefits and opportunities presented by arboreal camera trapping, it is likely to become an ever‐more popular method of studying arboreal species and systems. The information synthesized in this review provides guidance for future studies to help direct more reliable and robust ecological inferences from arboreal camera trapping.
Resumen
El fototrampeo arbóreo es un método emergente que brinda una técnica nueva y efectiva para responder a preguntas de investigación en una variedad de ecosistemas, y tiene la capacidad de mejorar nuestra compresión de una amplia gama de taxones. Sin embargo, mientras el fototrampeo terrestre ha recibido mucha atención, existen pocas pautas sobre cómo lidiar con los retos únicos de trabajar con cámaras en el ámbito arbóreo.
Nuestra revisión se basa en la experiencia de investigadores de seis continentes y en la literatura en general para evaluar las ventajas y desventajas del fototrampeo arbóreo y los retos a considerar al utilizar esta tecnología. También incluimos mini‐guías con información detallada sobre la literatura actual acerca del uso de cámaras trampa en los árboles, soportes utilizados para colocar las cámaras trampa, indicaciones y consejos para trepar árboles y acceder al dosel de manera segura, métodos para colocar las cámaras sin trepar y consejos para el manejo de interferencia en el funcionamiento de la cámara.
Nuestro estudio concluye que el fototrampeo arbóreo ha sido mayormente utilizado para el estudio de mamíferos en bosques. Sin embargo, esta metodología tiene el potencial de ser utilizada en un amplio rango de hábitats, incluyendo áreas urbanas, y taxones como aves, anfibios, invertebrados y plantas. Los métodos de fototrampeo arbóreo pueden mejorarse con una mayor comprensión de los factores que afectan la detección de especies. Los retos más comunes en el fototrampeo arbóreo son el acceso al sitio en el dosel donde se ubicará la cámara y la instalación de la misma. Estos retos se pueden superar entendiendo cuál es el mejor ángulo de orientación de la cámara, el manejo de las posibles fuentes de interferencia que se ubiquen delante de las cámaras, utilizando soportes apropiados para las cámaras y entrenando adecuadamente a los investigadores.
Dados los beneficios y las oportunidades presentados por el fototrampeo arbóreo, es probable que se convierta en un método cada vez más popular para estudiar especies y sistemas arbóreos. La información sintetizada en esta revisión proporciona una guía que ayudará a futuros estudios a realizar inferencias ecológicas más confiables y sólidas en base al fototrampeo arbóreo.
Résumé
Le piégeage photographique dans la couronne des arbres est une méthode en plein essor qui offre une technique novatrice et efficace pour répondre à des questions de recherche pour une variété d'écosystèmes, et permet d'améliorer notre compréhension d'une large diversité de taxons. Cependant, alors que le piégeage photographique au sol a reçu une grande attention, il y a peu de manuel pour répondre aux défis que posent les études dans le domaine de la canopée.
Notre analyse repose sur l'expertise de chercheurs provenant de six continents et sur la littérature générale pour étudier les avantages et désavantages du piégeage photographique en canopée, mais aussi les défis à prendre en compte quand cette technologie est utilisée. Nous intégrons des mini‐guides contenant des informations détaillées de la littérature actuelle sur les pièges photographiques et les supports utilisés en canopée, des conseils pour grimper en toute sécurité aux arbres, les méthodes pour déployer ces appareils sans grimper et des conseils pour limiter les interférences lors de leur fonctionnement.
Nous trouvons que les pièges photographiques en canopée ont été plus souvent utilisés pour étudier les mammifères dans les forêts, cette méthode ayant cependant un potentiel pour un large éventail d'habitats y compris les zones urbaines, et de taxons tels que les oiseaux, les amphibiens, les invertébrés, et les plantes. Les méthodes de piégeage photographique en canopée pourraient être optimisées en améliorant notre compréhension des facteurs qui affectent la détection des espèces. Les défis les plus courants du piégeage photographique sont le placement et l'accès au site de fixation des appareils. Ces problèmes peuvent être surmontés en identifiant les orientations les plus adaptées pour les appareils, en limitant les sources potentielles d'interférences devant les objectifs, en utilisant des supports appropriés ainsi qu'en formant correctement les chercheurs.
Compte tenu des bénéfices et des opportunités que représente l'usage du piégeage photographique en canopée, cette méthode est de plus en plus utilisée pour étudier les espèces dans la canopée. Les informations synthétisées dans cette revue fournissent des indications pour les études futures afin de permettre des déductions écologiques plus fiables et plus solides à partir du piégeage photographique dans la couronne des arbres.
Resumo
As armadilhas fotográficas em dossel arbóreo é um método emergente que fornece uma técnica nova e eficaz para responder a perguntas científicas em diversos ecossistemas e tem a capacidade de melhorar nossa compreensão de uma ampla gama de taxa. No entanto, embora o uso das armadilhas fotográficas terrestres tenha recebido muita atenção, existem poucas diretrizes sobre como lidar com os desafios exclusivos de trabalhar com câmeras em um ambiente arbóreo.
Nossa revisão baseia‐se na experiência de pesquisadores de seis continentes e na literatura geral para avaliar as vantagens e desvantagens das armadilhas fotográficas em árvores e os desafios a serem considerados ao usar essa tecnologia. Também incluímos mini‐guias com informações detalhadas sobre a literatura atual sobre o uso de armadilhas fotográficas, suportes usados para sua instalação, indicações e dicas para subir em árvores e acessar o dossel com segurança, métodos para colocar câmeras sem escalar e dicas para manejo de interferências na operação da câmera.
Nosso estudo conclui que as armadilhas fotográficas em dosseis arbóreos têm sido utilizadas principalmente para o estudo de mamíferos em florestas. No entanto, essa metodologia tem potencial para ser usada em uma ampla gama de habitats, incluindo áreas urbanas, e taxa como aves, anfíbios, invertebrados e plantas. Os métodos podem ser aprimorados com uma maior compreensão dos fatores que afetam a detecção de espécies. Os desafios mais comuns no uso das armadilhas fotográficas em árvores são o acesso ao local onde a câmera estará localizada no dossel, e a prórpia instalação destas câmeras. Esses desafios podem ser superados compreendendo o melhor ângulo de orientação da câmera, gerenciando fontes potenciais de interferência na frente das câmeras, usando suportes de câmera apropriados e treinando adequadamente os pesquisadores.
Dados os benefícios e oportunidades apresentados pelo uso das armadilhas fotográficas em árvores, é provável que se torne um método cada vez mais popular de estudar espécies e sistemas arbóreos. As informações sintetizadas nesta revisão fornecem orientações que ajudarão estudos futuros a fazer inferências ecológicas mais confiáveis e robustas com base no uso desta técnica.
摘要
作为一种新兴的技术方法, 树栖红外相机为我们探究多种生态系统中的科学问题提供了有效的技术支持, 可以进一步加深我们对广大生物类群的理解。然而, 相比广泛应用的地面相机监测技术, 我们依旧缺乏对于解决树栖红外相机应用相关问题的指导方针。
通过综述来自六大洲研究人员的专业技术知识和广泛的文献, 我们分析了树栖红外相机的优缺点及其实际应用中所面临的问题和挑战。同时基于现有文献信息, 我们撰写了树栖红外相机使用的迷你指南, 包括安装和固定相机的装置、爬树技巧和安全提示、无需攀爬部署相机的方法和解决干扰使相机正常工作的技巧。
结果发现树栖红外相机经常用于森林哺乳动物的研究, 但这种方法仍有其他潜在的应用, 如可应用于城市地区等的各种动物栖息地, 可应用于包括鸟类、两栖动物、无脊椎动物和植物等多种生物类群。通过进一步了解影响物种检测率的因素, 可以改进关于树栖红外相机的研究方法。树栖红外相机应用中最常见的挑战是相机的布置和相机位点的访问。这些问题可以通过确定正确的相机方向、处理相机镜头前的潜在干扰因素、使用合适的安装和固定装置及培训当地的研究人员来解决。
鉴于树栖红外相机的优点和所带来的机遇, 它很可能会成为研究树栖物种和生态系统更流行的技术方法。这篇综述提供的各种信息为未来相关研究提供了指导, 将有助于从树栖红外相机研究中获得更可靠和稳健的生态推论。
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