Biotropica最新文献

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.

Since consumers reflect the isotopic composition of an assimilated diet, stable isotopes can be a useful tool to address the feeding ecology of tropical snakes. This is the first study reporting carbon and nitrogen stable isotopic composition of Bothrops atrox (Linnaeus, 1758) living in different landscapes located in the lower Amazon river, encompassing four main natural landscapes of the Amazon: old-growth forests, várzeas (flooded forests), savannas, and pastures. Our null hypothesis is that the δ¹³C of forest specimens of B.atrox is more negative because forests are dominated by C₃ plants, while C₄ plants are common in the other landscapes. On the other hand, δ¹⁵N of forest specimens should be more positive, since the δ¹⁵N of old-growth forests are higher than plants of savanna, várzea, and pastures. Confirming our hypothesis, the δ¹³C of B. atrox scales of the Tapajós National Forest was approximate −25‰ to −24‰, increased to approximately −23.5‰ to −23.0‰ in the savanna and pasture, and to −21‰ in the várzea, showing an increased contribution of C₄-derived carbon. Some specimens of B. atrox had δ¹⁵N as high as 18‰, which is much higher than the average δ¹⁵N of the snake's prey (7‰), confirming the apex position of B. atrox in the Amazon region. The δ¹⁵N values of the forest specimens were 5‰ higher than the savanna specimens, and this difference decreased to 3‰ between the forest and the pasture, and the várzea specimens. Finally, there were not large differences between δ¹⁵N values of livers and scales in any of the landscapes, suggesting a constant diet through time, and reinforcing the possibility of the use of snake's scale as a less invasive and non-lethal tissue to analyze.

Abstract in Portuguese is available with online material.

Strawberry guava (waiawī, Psidium cattleyanum Sabine, Myrtaceae) is a small tree invasive on oceanic islands where it may alter forest ecosystem processes and community structure. To better understand the dynamics of its invasion in Hawaiian rainforests in anticipation of the release of a biocontrol agent, we measured growth and abundance of vertical stems ≥0.5 cm DBH for 16 years (2005–2020) in Metrosideros-Cibotium rainforest on windward Hawai'i Island. Specifically, we compared the growth and abundance of both shoots (originating from seed or from the root mat) and sprouts (originating above ground from established stems) in four replicate study sites. Mean stem density increased from 9562 stems/ha in 2005 to 26,595 stems/ha in 2020, the majority of which were stems <2 cm DBH. Early in the invasion, both density and per capita recruitment of shoots was greater than that of sprouts, but as overall stem density increased, sprout abundance and recruitment came to surpass that of shoots. Relative growth rates among small stems <2 cm DBH declined over time for both shoots and sprouts, but relative growth rates of sprouts were consistently greater than that of shoots after the first 3 years. The capacity of strawberry guava to recruit from both shoots and sprouts facilitates its invasion of rainforest, its persistence in the forest understory, and its response to canopy opening. Strawberry guava thus poses a considerable risk of stand replacement for Hawaiian rainforests. Stand management will require perpetual efforts to control both seed production and sprouting.

The composition and biodiversity of insect community assemblages are mediated by a complex set of biotic and abiotic factors. Among these factors are forest structure and atmospheric variables (like temperature and humidity), which are heavily influenced by frequent hurricane activity in the Caribbean. Despite this, changes in Caribbean insect assemblages as forests recover from hurricane disturbance are poorly documented. Butterflies represent a charismatic model taxon in biodiversity and conservation, and are thus an ideal subject for exemplifying these shifts in insect abundances and diversity across ecological succession. Here, we monitored butterfly communities in two Puerto Rican forests differing in structure (i.e., canopy height, tree size) to assess butterfly diversity, abundances, and community level wing traits (size and color) over 1 year, beginning 6 months after Hurricane Maria. Monthly sampling over the course of 1 year revealed no relationships between abundances and canopy openness or humidity; instead, species abundances fluctuated seasonally and were nonlinearly correlated with temperature. In contrast, wing size and color were linearly correlated with abiotic variables. Specifically, wings were larger in cooler and more open conditions. Wing color saturation and brightness were negatively correlated with humidity. Our results suggest that, first, a functional approach may provide better insight into the factors mediating species responses to disturbances. Second, further disentangling abundance seasonality from impacts of extreme disturbances necessitates long-term monitoring.

Abstract in Spanish is available with online material.