Primates are important seed dispersers in tropical forests, but they are being lost due to forest fragmentation. We compared post-dispersal seed fate and seedling density for the tree Dialium guianense, in forest fragments in which its main seed disperser, the mantled howler monkey (Alouatta palliata) is present, and in fragments in which it is absent. We also carried out a germination experiment to assess gut-passage effect. Seeds extracted from fruits had very low germination (2%) compared with defecated seeds (70%). Seeds in monkey faeces had a lower probability of being attacked by predators, but a higher probability of being attacked by fungus, when compared with seeds inside fruits. Seed fate was similar in fragments with vs. without monkeys, and in sites under parent trees vs. under monkey sleeping sites. Seedling density was highest under sleeping sites in fragments with monkeys, followed by sites under parent trees in fragments with monkeys, and it was lowest in uninhabited fragments, regardless of deposition site. Our study adds to an increasing line of evidence suggesting that loss of frugivores can have strong consequences for plant recruitment.

Dioecious plant populations have generally been considered to maintain sex ratios of 1:1 (Allen & Antos 1993, Carroll & Mulcahy 1993, Charnov 1982). The sex ratio does, however, change if the plants are growing in a stressful environment, often being male-biased under these conditions (Ortiz et al. 1998, 2002). This pattern has been explained by differences in how the sexes resolve their respective energy requirements (Obeso et al. 1998). Females generally assign more resources to reproduction in comparison to growth and maintenance than do males, and they are smaller and longer-lived (Allen & Antos 1993, Nicotra 1999, Obeso et al. 1998, Willson 1983). Thus their higher reproductive costs take a toll on females, modifying the population sex ratio in favour of males (Allen & Antos 1993, Lovett-Doust & Lovett-Doust 1988). However, in order to determine the reproductive cost it is necessary to consider the compensatory mechanisms (Obeso 2002). These reduce the reproductive cost and include plastic response in terms of plant architecture and plant physiology. For example, nutrient resorption is a process that may help decrease dependence on nutrient intake, thereby constituting an important nutrient economy mechanism that can also reduce the reproductive cost if a significant proportion of the nutrients had been reassigned to reproduction (Killingbeck 1986, Obeso 2002).

A new technique for estimation of tree species richness in tropical forests was developed and tested in this study. The missing species extrapolation technique is based on the assumption that the rate of accumulation of new species with increasing area is the same within sampled and unsampled areas of similar habitat within a region. This new technique was tested on four 1-ha sites of subtropical moist forest in Rio Bravo, Belize for which complete species counts of trees ≥10cm dbh are available. Estimates given by the technique are 115, 98, 93 and 106% of the actual species counts within the four sites. The accuracy of these estimates was found to be equal to or better than most others obtained by using existing methods of extrapolation. The missing species extrapolation technique was also applied to a 21-ha riparian forest patch in the Mountain Pine Ridge, Belize, where it was used to obtain an estimate of the number of tree species ≥10cm dbh in the entire patch.

The question as to whether predators preferentially kill sick or disabled individuals has been addressed by many ecologists working with different predator–prey systems. Rau & Caron (1979) showed that heavily infected moose were more susceptible to hunting. Kruuk (1972) observed that hyenas appeared to select sick animals in the Serengeti. Vorisek et al. (1998) demonstrated that voles infected with a species of Frenkelia were taken more frequently by buzzards. As a broad generalization, wherever prey capture is difficult and involves large energy expenditure a greater proportion of sick animals seems to be captured (Fitzgibbon & Fanshawe 1989, Holmes & Bethel 1972, Temple 1987). In a host–parasite association where the prey species is an intermediate host and the predator is the definitive host, the capture of the prey is often an essential part of the life cycle. Therefore any mechanism which makes the prey susceptible to predation would enhance the parasite's fitness. In such relationships the susceptibility induced by the parasite can be very specific to the predator host (Levri 1998). Freedman (1990) suggested that a mutualistic association between the predator and parasite might exist. A mutualistic relationship can be said to exist between a predator and a parasite if the cost of harbouring the parasite is less than the benefit of greater success in catching the prey. There is perhaps no demonstrated example of such a mutualism in natural populations since it is difficult to weigh the parasite cost against the predation benefit.

Continuing climate change may cause shifts in the adaptive ranges of plant species. But this impact is less understood for many species in the tropics. Here, we examined the distribution of the current and future potential suitable habitats of two native forest spices Piper capense and Aframomum corrorima. We have used MaxEnt software to predict the current and future suitable habitats of these species. Two future climate change scenarios, that is, middle (Representative Concentration Pathway [RCP 4.5]) and extreme (RCP 8.5) scenarios for years 2050 and 2070, were used. A total of 60 and 74 occurrence data of P. capense and A. corrorima, respectively, and 22 environmental variables were included. The effects of elevation, solar radiation index (SRI) and topographic position index (TPI) on suitable habitats of these species were tested using linear model in R. Precipitation of the driest quarter, SRI and TPI significantly affect future suitable habitats of P. capense and A. corrorima. Furthermore, there are significant elevational shifts of suitable habitats for both species under future scenarios (P < 0.001). These novel suitable habitats are located in moist Afromontane and Combretum-Terminalia vegetations. Our results suggest that conservation planning for these species should consider climate change factors including assisted migration.

To maintain savanna vegetation, mid-seasonal fire has been applied since 1961 in the Lamto Savanna (Côte d'Ivoire). However, this prescribed fire has not impeded tree encroachment during recent years, nor have its effects on insect assemblages been documented. Also the impact of tree intrusion on insect assemblages is poorly studied in savanna. To prevent tree density increasing, a change in fire regime might be a solution. In this study, we examined the effect of different fire regimes (early, mid-seasonal and late fires) on leaf-litter ant assemblages in order to suggest appropriate measures for preventing tree invasion without having an effect on insect communities. Sampling was implemented by combining pitfall trapping and leaf-litter sampling before and after three different fire regimes, early, mid-seasonal and late fires. While the ant species richness declined after the passage of early and mid-seasonal fires, significantly more species were found in the burnt savanna after the late fire. However, the losses or gains of species due to different fire regimes did not cause severe changes in the ant species composition. Of the functional groups identified, only the generalists and specialist predators were respectively strongly affected by the early and mid-seasonal fires, certainly due to micro-habitat modification. Based on the trends observed in the present study, we suggest sampling other invertebrate fauna in similar savanna plots to find out if other insect groups have similar reactions to the applied fire regimes.

Tropical frogs experience damaging effects from exposure to UV-B radiation, and some diurnally active, conspicuous species exhibit avoidance behaviours to high levels of UV-B. To determine if similar behaviours are present in other diurnal frogs, we experimentally compared UV-B avoidance in two common species of neotropical diurnal frogs – Oophaga pumilio, an aposematic poison frog and Craugastor bransfordii, a cryptic leaf-litter frog – in response to different levels of UV-B. Wild-caught frogs were tested in experimental arenas fitted with filters that permitted two different levels of UV-B (low: 14% vs. high: 84% UV-B). Both species spent significantly more time under the low UV-B filter, suggesting that behavioural preferences for lower levels of UV-B are common to different diurnal species. Furthermore, male O. pumilio significantly preferred lower levels of UV-B, whereas females did not exhibit a preference for lower UV-B, which may suggest differences in UV-B exposure or sensitivity and/or alternative mechanism(s) to avoid UV-B between sexes. Although limited in scope, the findings of our study suggest that UV-B avoidance may be a behavioural adaptation common to all diurnal frogs.

Southern pine beetles (Dendroctonus frontalis Zimmermann) and symbiotic fungi are associated with mass mortality in stands of Caribbean pine (Pinus caribaea Morelet). This study provides a 12.7-year assessment of semiochemical mediation between southern pine beetle and Caribbean pine in relation to concentrations of 4-allylanisole (estragole, methyl chavicol) and monoterpenes measured by gas chromatography–mass spectrometry in different seasons in premontane and coastal pine stands of Belize and Guatemala. Individual trees and stands with >2.5% (relative mass %) of 4-allylanisole in the xylem oleoresin exhibited significantly less beetle-induced mortality than those with <2.5%. Changes in relative levels of 4-allylanisole and monoterpenes during this study are consistent with seasonal temperature and cumulative water deficit effects and suggest bark beetle attack of P. caribaea may intensify in the future.

The importance of deterministic and stochastic processes in structuring ecological communities is an enduring debate. Although this debate is nearly a century old, the extent to which communities are structured by species interactions or chance events is a central issue in ecology. We examined the assemblages of plants living inside 119 birds’ nest ferns (Asplenium goudeyi), which are endemic to Lord Howe Island. Specifically, we investigated whether patterns of species richness and community composition were influenced by fern size, fern isolation and plant dispersal abilities. Fern size and fern isolation significantly predicted plant community richness. At the community level, plant composition patterns did not deviate from randomized expectations. Individual species occurrences increased with increasing community richness, and no species exclusions were observed. Wind-dispersed taxa, which accounted for 29% of all species, were well represented in isolated ferns. Comparatively, poorer dispersers were confined to ferns nearest the forest at the base of the cliffs. We suggest that dispersal plays a key role in structuring plant communities living within birds’ nest ferns, and that species interactions are less important. Our study emphasizes the importance of epiphytes with a nest-like growth form as habitat for plants in a harsh environment.

Polymorphism is common in nature, but few Heliconius species are polymorphic for wing colour patterns. Eastern Brazil H. erato phyllis populations are polymorphic for hindwing elements (red raylets) and studies suggest that trait distribution varies seasonally. We carried a 3-y sampling to evaluate the hypothesis that season, wing length and pollen foraging were associated with morph diversity. Individual phenotypes were scored with regards to number of red elements in the dry and in the wet seasons. Co-mimic H. melpomene nanna was also analysed. We scored 432 H. erato and 513 H. melpomene. Our results confirm polymorphism in H. erato, with individuals showing from one to eight elements, with a mode between five and six. We found that H. melpomene is polymorphic for red dots, varying from two to five (mode = 2). Red basal dots were mostly invariant in H. erato. Even though we found a seasonal change in pollen loads, we found no association between individual phenotypes and season, pollen load scores, or wing length. We reject the hypothesis of ecological correlates of morph frequency, and suggest that trait colour variation in the two species is linked to and constrained by effects on mate recognition.

Nectarivorous flower mites can reduce the volume of nectar available to pollinators. The effects of the flower mite Proctolaelaps sp. on nectar availability in flowers of a melittophilous bromeliad Neoregelia johannis (Bromeliaceae) was evaluated in a coastal rain forest in south-eastern Brazil. In a randomized block experiment utilizing 18 flower pairs, one per bromeliad ramet, pollinators (Bombus morio) and mites were excluded, and then nectar volume, sugar concentration and sugar mass were quantified over the anthesis period. Mites significantly reduced nectar volume early in the morning (6h00–8h00), but not later (10h00–12h00). Mites decreased total volume of nectar available up to 22%. Sugar concentration in nectar was higher earlier in the morning, and decreased between 10h00–12h00. The pronounced consumption of nectar by mites during the period of higher sugar concentration reduced the total amount of sugar available to pollinators by 31%. This is the first study showing that flower mites decrease nectar rewards in a melittophilous plant. Because nectar volume by itself incompletely describes nectar production rates and the effects of nectar removal by flower mites on the availability of sugar, our study highlights the inclusion of sugar content in future studies assessing the effects of thieves on nectar production rates.

Staminodes are sterile stamens that produce no pollen, exhibit diverse structures and perform various functions. Flowers of Phanera yunnanensis possess three fertile stamens with large anthers and long filaments, and seven staminodes with tiny anthers and short filaments. To investigate the adaptive significance of staminodes in this species, we studied effects of staminode removal on pollen removal and deposition, flower visitation rate and fruit set in Xishuangbanna, south-western China. Four species of nectar-foraging pollinators visited flowers, mostly Amegilla zonata and Apis cerana (2.80 ± 0.15 and 1.76 ± 0.41 visits h−1 per flower, respectively). Staminode removal did not affect fruit set, but increased visitation by A. cerana by 2.6-fold, reduced visitation by A. zonata by 68% and increased the pollen removal rate for both pollinators (all effects were significant). Staminode removal significantly reduced pollen deposition rate for A. zonata, but not for A. cerana. These results suggest that the staminodes of P. yunnanensis filter which insects act as pollinators and affect pollen removal and deposition rates. By reducing pollen removal rates, staminodes may implement a pollen-dispensing schedule that spreads pollen dispersal from individual flowers over multiple pollinators. By altering pollen deposition rates, staminodes may influence reproductive fitness in other ways.

To investigate the influence of forests and agroforestry systems on fruit consumption by birds, we studied two landscapes, one covered predominantly with forests and the other dominated by traditional shade cocoa plantations. In each landscape, we sampled three forest fragments and three shade cocoa plantations. We placed 15 artificial fruits in 25, 1–2-m-tall shrubs spaced every 50 m and evaluated the detection and consumption of fruits after 72 h. We used hemispherical photographs positioned above each fruit station to evaluate canopy openness. We found a statistically significant difference in fruit consumption between landscapes, which means that more fruits were detected and consumed in the forest-dominated landscape. However, forests and shade cocoa plantations within each landscape exhibited similar fruit consumption. Canopy openness was similar between the landscapes, however, the cocoa plantations exhibited greater canopy openness than forests. The results of this study reinforce the importance of the presence of forests in the agricultural landscape. Thus, to evaluate the capacity of agroforest to protect species and maintain ecological interactions it is also necessary to consider the landscape context.

Oil palm is one of Southeast Asia’s most common crops, and its expansion has caused substantial modification of natural habitats and put increasing pressure on biodiversity. Rising global demand for vegetable oil, coupled with oil palm’s high yield per unit area and the versatility of the palm oil product, has driven the expansion of oil palm agriculture in the region. Therefore, it is critical to identify management practices that can support biodiversity in plantations without exacerbating negative impacts on the environment. This study focuses on day-flying Lepidoptera (butterflies and moths), which contribute to the ecosystem functioning as pollinators, prey, and herbivore species. We assessed whether density and behaviours of day-flying Lepidoptera varied between different habitats within oil palm plantations and across seasons. We surveyed the density and behaviours of Lepidoptera communities in mature industrial oil palm plantations within the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme sites, in Riau, Indonesia. We surveyed two distinct habitats within the plantations in March and September 2013: Edge habitats, which were bordered by plantation roads on one side, and Core habitats in the centre of oil palm planting blocks. We conducted analyses on the effect of habitat type and season on both the overall density and behaviour of Lepidoptera communities and, independently, on the most common species. In our surveys, we observed 1464 individuals across 41 species, with a significantly higher density in Edge than in Core habitats. While there was no significant difference between overall density in March and September surveys, there was an interaction between season and habitat, with density increasing more markedly in Edge than Core areas in September. There was also a significant effect of habitat and season on behavioural time budget for the community as a whole, with more active behaviours, such as foraging and mating, being recorded more frequently in Edge than Core habitats, and more commonly in September than March. The effect of habitat type, season, and their interaction differed between the six most common species. Our findings indicate that Lepidoptera abundance is affected by habitat characteristics in a plantation and can therefore be influenced by plantation management practices. In particular, our study highlights the value of road edges and paths in plantations for day-flying Lepidoptera. We suggest that increased non-crop vegetation in these areas, achieved through reduced clearing practices or planting of flowering plants, could foster abundant and active butterfly communities in plantations. These practices could form part of sustainability management recommendations for oil palm, such as those of the Roundtable on Sustainable Palm Oil.

Necrophagous Diptera were sampled in a seasonal tropical mixed forest in Hong Kong from February 1985 to May 1986 using carrion-baited traps. Six families of flies were caught but only Calliphoridae, Muscidae and Sarcophagidae were considered. They made up a total of 14,669 flies of 21 species in the sample. Total species abundance followed Fisher's log-series distribution. The commonest five species were calliphorids, constituting 79.44% of the total combined catch. Temperature was apparently the main factor affecting seasonality of necrophagous Diptera in Hong Kong. Fluctuations in total abundance, species richness and H' followed seasonal changes in weekly mean air temperatures.

Flowers of Aphelandra sinclairiana have features of flowers pollinated by hermit humming-birds (long corollas) and of those pollinated by territorial humming-birds (dilute nectar, clustered distribution). Flowers in large clumps at the peak of the blooming season were pollinated by two territorial humming-birds, but at the end of the season or in isolated plants the main avian pollinator was the non-territorial hermit Phaethornis superciliosus. Visits by avian nectar thieves were more frequent at high flower densities. The reproductive output of inflorescences was similar at different levels of flower aggregation. Aphelandra flowers in large clumps could exchange pollen with extraterritorial plants because territorial humming-birds did not completely exclude pollinating hermits. The commonest nectar thief at high flower aggregations was the passerine Vermivora peregrina, the second most common nectar thief was the hermit Phaethornis longuemareus.

Ants (Hymenoptera: Formicidae) are important predators of herbivorous insects on plants (Rosumek et al. 2009). Ant removal or absence may result in negative indirect effects on plants, as herbivore abundance and herbivory increase and plant growth and reproduction decline (Rosumek et al. 2009, Schmitz et al. 2000). Ant presence on plants often results from a mutualistic interaction. For example, strong highly coevolved ant–plant mutualisms are found on myrmecophytic plants that house ants in domatia (specialized nesting sites). Weaker mutualistic associations are found with myrmecophilic plants that only offer extra-floral nectaries (EFNs) or food bodies to attract ants, or on other plants hosting honeydew-producing hemipterans (indirect ant–plant interactions) that mediate ant abundance (Hölldobler & Wilson 1990). However, in most cases, plants and arboreal ants form more passive associations, where ants nest in the natural cavities of branches or bark, or construct carton nests on plant substrates (Hölldobler & Wilson 1990) and the only reward plants offer these ants is the use of their substrates. In these situations the indirect effect of ants on plants is merely by chance, a byproduct of ant presence (byproduct association).

Fragmented forest landscapes with large proportions of edge area are common in the tropics, though little is known about functional responses of trees to edge effects. Foliar δ13C can increase our understanding of tree function, as these values reflect changes in ci/ca as trees respond to environmental gradients. We expected that foliar δ13C would be enriched, indicating a decline in ci/ca, in Pentaclethra macroloba trees growing at forest edges in north-eastern Costa Rica. We also anticipated this isotopic shift in δ13C values of soil carbon and soil respired CO2. Three transects perpendicular to forest edges were established at three study sites, and six plots per transect were located 0–300 m from edges. Within plots, foliage, soil and soil respired CO2 were collected for isotopic analyses. Foliar δ13C, thus ci/ca, and soil carbon δ13C did not vary along the edge to interior gradient. δ13C for canopy and understorey foliage averaged −29.7‰ and −32.5‰, respectively, while soil carbon δ13C averaged −28.0‰. Soil respired CO2 δ13C ranged from −29.2‰ to −28.6‰ and was significantly depleted within 50 m of edges. The predominant lack of functional responses at forest edges indicates that P. macroloba trees are robust and these forests are minimally influenced by edge effects.