Biotropica最新文献

Conferences of the Association of Tropical Biology and Conservation aim to foster scientific understanding and conservation of tropical ecosystems by supporting research communication and collaboration among biologists and conservation practitioners working in the tropics. The annual meeting in 2019 was held in Antananarivo, Madagascar. To assess the importance of the meeting in the academic and professional development of the 89 Malagasy participants, an anonymous questionnaire survey was conducted 12 months after the meeting. Feedback from the respondents indicated that the three most important aspects of the meeting were developing networks (40.0%); improving professional skills (encompassing public speaking, data analysis, comments on their presentations, writing capacity, and ability to publish) (30.0%); and gaining visibility (16.7%). Among the respondents, 49.0% have subsequently become interest in problems associated with deforestation, 28.6% in topics related to conservation biology, 14.3% to new approaches for solving conservation problems, and 8.2% in food security issues. The survey found that language barriers and lack of funds for research (about 64.6% in both cases) were the most limiting factors to advance research programs for national scientists. The meeting also acknowledged three Malagasy scientists who received Association of Tropical Biology and Conservation awards. An important outcome was the “Ivato Declaration” a petition to bring to the world's attention the current conservation situation on the island and for which nearly 7000 people from 124 countries signed. The survey indicated that national scientists and students received multiple benefits and new opportunities from their participation in the meeting.

Abstract in French is available with online material.

Community-based conservation can play an important role in preserving biodiversity, but it is unclear whether such benefits extend to invertebrate communities; in particular, baseline data for insect communities is lacking to assess efficacy of conservation efforts. Here we evaluate ant assemblages across three habitats, protected within the Wechiau Community Hippo Sanctuary (WCHS) in the Upper West Region of Ghana. We compare relative ant species diversity and uniqueness between the sanctuary's Guinea savannah, riparian forest, and floodplain habitats. Ants were collected with other invertebrates using malaise traps, pitfall traps, and yellow pan traps between 2001 and 2011 multiple times per year. From these data, we compiled a list of ant species found, castes collected, and functional groups, and evaluated the differences in ant diversity among the habitats using accumulation curves, assemblage structure comparison, and Morisita-Horn indices. We also compared the overall WCHS assemblage to other ant assemblages in Western Africa to gain a clearer understanding of relative diversity and uniqueness. We collected 83 species from seven subfamilies and 44 genera; 14 of the species were previously unrecorded in Ghana, including one ant species new to science. Ant species diversity differed among habitats in assemblage composition but not significantly in species richness. We found that the WCHS ant assemblage was relatively unique, sharing only about 35% of species found in similar Côte d'Ivoire habitats, and 25% of other Ghanaian assemblages. Some species present in the WCHS were not found in any of the other compared assemblages. We conclude that community-based conservation initiatives like the WCHS may play an important role in conserving the biodiversity of ants.

Tree life history strategies are correlated with functional plant traits, such as wood density, moisture content, bark thickness, and nitrogen content; these traits affect the nutrients available to xylophagous insects. Cerambycid beetles feed on substrates that vary in these traits, but little is known about how they affect community composition. The goal of this project is to explore the community composition of two cerambycid subfamilies (Cerambycinae and Lamiinae) according to the wood traits in the wood they eat. In a salvage project conducted adjacent to the Panama Canal, trees were felled and exposed to Cerambycidae for oviposition. Disks from branches of differing thickness from the same plant individuals were used to calculate wood density, moisture content, and bark thickness in the field; nitrogen data were acquired offsite. Thick and thin branches tended to differ in wood trait values; therefore, data were analyzed separately in subsequent analyses. In thin branches, cerambycid abundance and species richness were higher in samples with less dense, moister wood, and thicker bark. Thick branches showed similar trends, but the wood traits accounted for little variability in beetle abundance or species richness. There were no significant regressions between beetle data and nitrogen. Cerambycines emerged more slowly, and from denser, drier wood, than lamiines. Cerambycines might be more drought-tolerant than lamiines, and therefore, more resistant to the longer, more severe dry seasons that are predicted to occur due to climate change.

Abstract in Spanish is available with online material.

Coastal dry tropical forests (CDTFs) are important yet vulnerable ecosystems. In this paper, we highlight the special conservation issues facing CDTFs by focusing on one variant of the type, those that occupy limestone substrate in the northeastern Caribbean. Our analysis draws largely from the coastal terrestrial broadleaf forests of the northern Bahamas, the Florida Keys, and southwestern Puerto Rico. Based on the surveys of storm surge recorded during major hurricanes during the last 50 years, we define CDTFs as coastal terrestrial broadleaf forests on ground surfaces elevated up to 5 m above sea level and occurring within 5 km of the coast. These forests are not only threatened by land-use change from urbanization but also climate-driven sea level rise (SLR) and hurricanes, which have degraded them and reduced their extent. CDTFs are distinguished from other dry tropical forests by the occasional influence of marine water incursion during periodic storms, requiring species common to these forests to have some level of salt tolerance despite experiencing well-drained, fresh water conditions during most of their life span. With precipitation being the sole freshwater source for most CDTFs, SLR and the resulting salinization in the rooting zone subjects these forests to increasingly stressful conditions. Hence, even a modest rise in sea level can push numerous imperiled and endangered species and coastal terrestrial broadleaf communities to the edge of their tolerance, causing a decline in extent or their complete disappearance. Outside of protected areas, rapid urbanization has fragmented these forests and reduced their extent, which in turn have modified the interaction between rising seas and forest function. This work emphasizes the need for refined risk assessments to be completed and for conservation measures to be enforced so that resources can be directed appropriately to prevent further loss of CDTFs.

Abstract in Spanish is available with online material.

Lianas shape tropical forest species composition, structure, and dynamics. Increasing climate fluctuation and anthropogenic disturbances increase liana abundance. Despite the increasing number of liana studies in India, only a few have examined the distribution and association of hosts with lianas, or liana–host interaction networks to determine their functional significance and conservational value. Therefore, our objective was to fill the knowledge gap about the diversity, abundance, and network structure of liana–host interactions in response to logging disturbance in a wet evergreen forest of Uppangala in central Western Ghats, India. We sampled lianas ≥1 cm in diameter at 1.3 m from the base and their host trees in thirty 20 m × 20 m plots in selectively logged and unlogged forest management regimes. We evaluated liana–host tree interactions in logged and unlogged forests and retrieved community-level measures (nestedness, connectance, modularity, and network specialization index) and species-level indicators (species specialization index). Diversity and abundance of liana species were considerably greater in the selectively logged forest site. The logged forest site had compartmentalization, anti-nestedness, and network specialization, while unlogged forests were not showing any significant network structure. Most species of lianas and hosts were peripherals, but others were structurally important (connectors, module hubs, and network hubs) in the two forest sites. Forest management regimes had distinct structurally significant species.

Plants have evolved mechanisms to track seasonal variation in environmental resources, enabling them to time key life-history events to appropriate seasons. While the proximate cues for flowering initiation are well documented in the temperate region, it is still unclear what the flowering cues are in the tropics, especially in the subtropics. Our study compared first flowering dates (FFDs) predicted by eight hypothesized proximate cues concerning photoperiod, mean and directional changes in solar irradiance and warm/cool temperature, and rainfall with flowering dates observed over 19 years of weekly monitoring for 16 species in a subtropical rain forest. We observed considerable interannual variation in the median FFDs for the study species, ranging from 21 to 101 days. The early-spring flowering species tended to have greater interannual variation in FFDs than the summer flowering species. For 13 study species, temperature cues best explained interannual variation in FFDs. Cool temperatures in the previous fall/winter and warm temperatures in the current spring (or previous summer) might trigger the onset of flowering in these 13 species. Cues associated with photoperiod and irradiance also predicted interannual variation in FFDs with small root mean square error (<1.5 census intervals) for 12 species but generally had higher prediction errors than temperature-related cues. Cues associated with seasonal variation in rainfall failed to predict flowering times in any species. Our results suggest that future changes in temperature may alter flowering times for most species in subtropical forests, leading to changes in ecosystem processes and biosphere feedback to the climate system.

Abstract in Chinese is available with online material.

植物演化出許多不同的機制來追蹤環境資源的季節變化，讓關鍵的生活史事件發生在適當的季節。誘發植物開花的氣候因子在溫帶地區已有許多研究，但在熱帶，特別是亞熱帶地區，這類研究仍然相當缺乏。我們的研究使用了在亞熱帶雨林中進行19年的長期物候監測資料，分析16種植物的首次開花日期(first flowering date, FFD)的年間變化，以及光週期、太陽輻射、積溫、低溫以及雨量對於開花時間的影響。我們發現各植物的FFDs年間變化相當大，範圍從21到101天不等，早春開花的物種傾向於比夏季開花的物種具有更大的FFDs年間變異。溫度的年間變化可以準確預測13種植物的FFDs，前一年秋季/冬季的低溫和當年春季(或去年夏季)的高溫可能會誘發這13種植物的花芽發育。光周期和日照輻射也能夠預測12種植物的FFDs的年際變化，但通常比與溫度相關的物候模式具有較高的預測誤差。降雨量的年間變化並無法預測本研究16種植物的開花時間。由我們的研究結果推論，未來的氣溫變化可能會改變亞熱帶森林中大多數植物的開花時間，從而改變生態系與生物圈對氣候系統的反饋.

Due to the threats posed by changes in land-use patterns to many species, it is necessary to have a proper description of the distribution of a range-limited species. We aimed to assess the spatial distribution and social organization of Nilgiri langurs, and to model the potential distribution of mixed-species groups of Nilgiri and Hanuman langurs (Semnopithecus priam or S. hypoleucos). We used our database of systematic surveys from 1994 to 2021 as well as the available literature. Nilgiri langurs are found in five regions in the Western Ghats: Nilgiri-Brahmagiri, Siruvani, Anamalai- Parambikulam, Cardamom Hills, and Periyar-Agastyamalai, each with many fragmented sub-populations. They live in mixed-sex groups ranging from 2 to 27 individuals with a mean group size of 9.10 ± 5.54SD and a few all-male bands. The groups with one or two males, several adult females, and immature individuals is a typical trait of the Asian colobine social organization. The potential distribution of mixed-species groups of Nilgiri and Hanuman langurs indicates that they are found on the eastern slopes of the Western Ghats between 500 and 800 m a.s.l, which is a transition zone of evergreen to dry forest landscapes. A detailed description of one of the populations is presented as a case study of fragmentation where the results revealed strategies to manage populations in such landscapes. Since most habitats, especially the rainforest regions, in the Western Ghats, are highly fragmented impacting many species, the results of this study may serve as a model for wildlife management in the Western Ghats.

Rainforests on high tropical mountains are globally important species diversity hotspots. We studied amphibians along an extensive rainforest elevation gradient on Mt. Wilhelm (4509 m) in Papua New Guinea. We established eight sites at 500 m elevation increments between 200 and 3700 m a.s.l. and relate their community composition to the known species pool of New Guinea island. We recorded 3390 frogs from 55 species, which is three times more species than at any local community along the elevation gradient. Species diversity peaked at 1700 m a.s.l. for Mt. Wilhelm communities, and at 500–1100 m a.s.l. in the broader New Guinea fauna, probably reflecting increasing speciation and decreasing dispersal rates with increasing elevation. The beta diversity between frog communities was high and increased with increasing elevation. The change in frog community composition across 500 m elevation corresponded to the change over 200 km distance within lowland forests. A majority of frog species were distributed over narrow <500 m elevational ranges, at Mt Wilhelm and the New Guinea fauna more broadly. We did not detect Rapoport's pattern of wider elevation range for species at higher elevations than for lowland species, for Mt. Wilhelm communities or the New Guinea fauna. The high beta diversity patterns along elevation gradients generated by rapid species turnover with narrow elevation ranges make frog communities vulnerable to change in environment, including climate change.

Abstract in Melanesian Pidgin is available with online material.

The army ant Eciton burchellii boasts more animal associates than any other animal species yet described, but the relationship between army ants and other ant species has only been studied in the context of predation. The waste deposits (middens) of army ant colonies are nitrogen-rich, a potentially high-value nutrient source for leaflitter arthropods. We explored this bottom-up role of army ant middens in the context of tropical ant communities. Our three main questions were the followings: (1) Which ant species forage on army-ant middens? (2) How does the bi-phasic life cycle of army ant colonies (affecting midden size, persistence, and abundance) affect which and how many ant species a midden boasts? (3) How do the ants that forage on army ant middens differ across elevations? Across 39 bivouacs, we found 36 species of ants foraging on army ant middens. These included highly predatory ants, nitrogen-limited arboreal ants, and fungus-farming ants. Per-midden richness was significantly lower for the usually smaller middens deposited during the nomadic phase and was higher for the typically larger middens deposited during the statary phase. Per-midden richness was not significantly different across elevations, but there was far greater species turnover across elevations than across phases within the same elevational site. Our results suggest that army ant middens are an important resource for a wide variety of tropical ants, informing a better understanding of the complex network of associations revolving around this keystone species.

Abstract in Spanish is available with online material

Frugivorous animals play crucial roles dispersing seeds away from parental plants and influencing plant recruitment. Most studies focus on comparisons of seed dispersal services provided by distinct species of animals, but neglect how within-species variation may affect dispersal. Individual traits, such as body mass and sex, are related to metabolic rates, gut load capacity, and transit times that potentially influence dispersal quantity and quality. Here, we aim at answering if individual traits (body mass and sex) of Pale-breasted Thrushes (Turdus leucomelas) affect seed dispersal quality by testing the following hypotheses (a) individual traits influence seed retention time and germination, (b) seed retention time affects seed germination, and (c) seed passage through the gut enhances germination. We found that females retained seeds in the gut for longer periods than males. Gut passed and manually depulped seeds had similar germination success. However, heavier birds, irrespective of sex, had longer seed retention times and promoted higher germination. Our results indicate that intraspecific differences in morphological traits of frugivores are a source of variation in dispersal outputs and may help to explain complex patterns of seed dispersal. We highlight the importance of considering the quality of seed dispersal at an individual-level, as well as at a species-level, and reinforce that some individuals may contribute more to seed germination, and potentially recruitment, than others. Finally, a decrease in body masses of tropical birds in response to global warming may cascade to a decrease in seed dispersal quality.

Abstract in Portuguese is available with online material.