Biotropica最新文献

Flower–animal interactions encompass a continuum of mutualistic to antagonistic behaviors. Although the importance of pollinators in interaction networks has been widely reported, the role of floral antagonists remains overlooked. In Collaea cipoensis, an endemic shrub from southeastern Brazil, we modeled an individual-based network assessing the flower visitors' functional behavior and tested if plant centrality increases fitness. Centrality indicates how well-connected a given plant is with the rest of the conspecifics through shared flower visitors. Specifically, we tested if flower visitor interactions are amplified by many-flowered individuals, and whether the relationship between centrality and plant fitness encompasses the effects of mutualists or antagonists. Subsequently, we quantified each visiting species' effectiveness. Antagonistic interactions were the most frequent in the network (97% of visits), primarily conducted by the nectar-robbing bee Trigona spinipes (66%), which was also the most central species and detrimental antagonist. The hummingbirds Colibri serrirostris and Eupatomena macroura were the most efficient pollinators, with a high contribution to the quantity—floral visitation—and the quality—viable seeds—components, respectively. Many-flowered plants showed greater centrality, which boosted the plant's cohesion in the network and increased flower visitation. Accordingly, many-flowered plants were better connected, mainly due to antagonistic visitors. Thus, centrality increases were not positively translated into more reproductive success. Our results reinforce the dynamic scenarios of flower–animal interactions, with consequences to plant reproductive ecology. We highlight the importance of incorporating distinct types of interactions to unveil the complexity of interacting systems, that when not explored, hide potential evolutionary consequences for plant reproductive success.

Abstract in Portuguese is available with online material.

Landscape characteristics can influence gene flow depending on the species ability to disperse. This imposes different levels of resistance to movement, determining the genetic structure and diversity of populations. Waterfalls and rapids in the Amazon basin have been suggested as contributing factors to the diversification and genetic structure of freshwater species, including turtles. Thus, along some main rivers of the Brazilian Amazon: Juruá, Madeira, Amazonas, Trombetas, Tapajós, Xingu, Tocantins, and Araguaia, we evaluated the spatial distribution of genetic diversity and characterized the population structure of Podocnemis unifilis, a widely distributed and endangered Amazonian turtle, using the mitochondrial DNA control region. We tested for isolation by geographic distance and by resistance models through an integrative approach using genetic, geographic, and ecological data, comparing these matrices with genetic distance. We found heterogeneous levels of genetic diversity and no spatial patterns. Results supported the isolation by resistance hypothesis, where the movement of individuals was influenced by freshwater, vegetational, climatological, and geomorphological variables, explaining the genetic distance of P. unifilis. Rapids and waterfalls impose greater resistance although they are barriers with different levels of permeability to the P. unifilis gene flow. Thus, the idiosyncrasies of each sub-basin must be considered in the interpretation of the patterns found in assessing phylogeographic history.

Abstract in Portuguese is available with online material.

Fire and large mammal herbivores (LMH) are the principal top-down forces maintaining savanna structure. Nonetheless, experiments designed to investigate interactions between fire and LMH are rare in savannas, and relationships between environmental variation and biodiversity in the context of fire and LMH are poorly understood. This study addresses these gaps by manipulating the presence of LMH and early and late dry season fires in a tropical African savanna. In addition, this work simultaneously explores environmental variables including soil and foliar quality, vegetation cover, and nearby water sources to more holistically describe factors affecting savanna functioning and biodiversity. After 1 year of experimental treatments, changes in vegetation were already apparent. Shrub abundance and richness and grass richness were higher in the absence of LMH, while grass biomass increased three-fold in burned plots as compared to unburned plots. Foliar nutrients tended to increase in open plots, while phenolics decreased. Amphibian abundance decreased with early burns and was higher with LMH. In contrast, small mammal abundance and richness increased without LMH and with time since fire. Richness and foraging of LMH were highest after late burns. These results demonstrate ecosystem-wide effects of LMH, illustrating the importance of considering multiple taxa when designing fire management programs. For example, burning negatively affected amphibians and small mammals and changed vegetation at the same time it increased LMH foraging. In the long-term, this experiment will shed light on interacting effects of fire and LMH on savanna biodiversity and function.

Abstract in Portuguese is available with the online material.

The subtropical rainforest shrub Graptophyllum reticulatum (Acanthaceae) occurs in only a few populations within a 20-kilometer range in the Sunshine Coast, south-east Queensland, Australia. This endangered plant has been subject to habitat degradation and loss, mostly due to land clearing and urbanization. In the past decades, conservation measures such as land protection and translocation have been put in place to protect the species' wild populations. The aim of the study was to analyze the viability of the species' populations in the long term while assessing the effectiveness of land protection and translocation. Demographic data was collected every decade since 2000; for this study, we resurveyed all known populations including a translocated population and two recently discovered populations. We found that the average number of plants per population has doubled since 2000, except in one population that underwent land clearing. However, after being reduced by 70%, plant abundance in this population has been increasing, giving evidence of natural post-clearing recovery. We developed population growth models for population viability analysis in best, average, and worst-case scenarios to predict the species' viability over the next 100 years. All populations are expected to grow in the next 100 years, except in the worst-case scenario in which removing land protection from the model led to an 80% decline in the total number of plants within 100 years, highlighting the importance of land protection for species' conservation. Overall, if current conservation efforts are maintained, this endangered species is likely to persist for the next 100 years.

Savanna systems are among the most sensitive to future climate and land-use change, yet we lack robust, direct quantifications of savanna carbon cycling. Together with fire, decomposition is the main process by which the carbon and nutrients are recycled and made available again to plants. Decomposition is largely mediated by microbes and soil invertebrates. Using a novel large-scale termite suppression experiment, we quantify, for the first time, the relative contribution of microbes, termites, and other invertebrates to the decomposition of wood (fresh native and dry non-native), dry dung, and grass in a mesic savanna. We found that termites were responsible for two thirds of the mass loss from dry wood and a third of the mass loss from fresh native wood, dry dung, and dry grass. Microbes were wholly responsible for the difference as there was no evidence of other invertebrates contributing to decomposition, even with fresh wood. Using multiple substrates in savanna decomposition studies is important where a mixture of contrasting life forms occur because both the rates of decomposition and the dominant agent varied considerably. In addition, including both a dry non-native and fresh native wood cast light on possible explanatory variables such as wood density, green-ness and the presence of bark, and the necessity of teasing these variables apart in future studies. Termites stand apart from all other insects in their impact on decomposition within savannas and should be acknowledged alongside microbes and fire as the primary agents of wood, grass, and dry dung turnover in global carbon models.

Highlands are of paramount importance to the study of evolution as they are frequently implicated in historical and ecological processes that generate and maintain biological diversity. In northeastern Brazil, sparse rainforest remnants located in highlands north of the São Francisco River are surrounded by the dry and open landscape of the Caatinga biome. Earlier studies suggested that these forests were historical refuges to the rainforest fauna and flora during Pleistocene's climatic cycles. However, it is still unclear whether populations in distinct highlands experienced phenotypic differentiation as a result of adaptation to environmental conditions of each forest remnant. Herein, we used two frog species widely distributed and ecologically different, Dendropsophus oliveirai, a habitat specialist, and Physalaemus cuvieri, a habitat generalist, to investigate the relationships between environmental variation, geographic, genetic, and body size distance with advertisement call variation among populations inhabiting different highlands. Our results indicated that acoustic variation among P. cuvieri populations is strongly influenced by environmental variation, but also by the geographic distance among populations. In D. oliveirai, environment is also the most influent factor on acoustic variation, followed by a lower influence of genetic and morphological variation. Associations between environmental and geographic factors suggest indirect effects of geographic distance on acoustic variation in both species through an environmental gradient. We believe that selective processes and isolation by distance possibly act together in driving interpopulational acoustic variation with habitat-specific species being more affected by geographic isolation in suitable habitats.

Abstract in Portuguese is available with online material.

Biotropica, the flagship journal of the Association for Tropical Biology and Conservation, is a highly regarded source of original research on the ecology, conservation, and management of all tropical ecosystems, and on the evolution, behavior, and population biology of tropical organisms. We aim for timely, fair, transparent, and constructive reviews and editorial decisions. We value a geographically diverse Editorial Board with broad expertise in tropical taxa and ecological, evolutionary, and conservation research, reflecting our diverse authorship and readership.

In 2023, we advertised the first Open Call for service on our Editorial Board. The response was overwhelmingly positive. In the end, we selected 14 new Subject Editors from a very qualified pool (Figure 1). Please join us in welcoming our new Subject Editors and thanking those who are rotating off the Editorial Board. The Open Call for editorial service will be an annual call, so please consider serving on our Board.

Bat pollination at the range margin in the southwestern Neotropics has been largely unexplored. We provide for the first time direct evidence on bat pollination, visitation rate, and efficiency for three species of the Southern Andean Yungas. These interactions are valuable targets for future conservation efforts in this endangered ecosystem.

Abstract in Spanish is available with online material.

Orchids are the most heavily traded plant group globally, putting pressure on wild populations in many source countries like the Philippines. Despite its rich orchid diversity, there remains a notable gap in understanding the factors driving orchid trade within the country. To address this knowledge gap and support orchid conservation efforts, we utilized a 5-year orchid diversity dataset extensively collected through floristic field and village garden surveys in one of the largest key biodiversity areas in the southern Philippines. We employed a trait-based approach to investigate ecological drivers of local orchid collection within this source area. Our results show that around 36% of local orchid diversity have predicted collection risks of ≥50%. Notably, locally collected orchid species exhibited multiple, large, and conspicuously colored flowers that are found in low-elevation forests and higher up in forest stratum. Elevational distribution and flower size emerged as the strongest predictors, potentially influencing collection preferences. Our analysis of predicted collection risks underscores the vulnerability of both threatened and non-threatened orchid species to local collection pressures. Moreover, we highlight the practical utility of our trait-based approach in predicting risks and informing management strategies for local orchid conservation. This research marks a significant step toward identifying ecological drivers influencing orchid trade at its source, providing insights that can inform targeted conservation strategies across many key biodiversity areas for this highly diverse, charismatic, and threatened plant family.

Plant thermoregulation is essential for understanding the potential effects of climate change on terrestrial ecosystems. This study provides evidence indicating variation of leaf functional traits and leaf-to-air temperature across the elevation gradient. These results support the existence of distinct plant adaptations for thermoregulation across different elevation zones.

Abstract in Spanish is available with online material.