Search

Tropical forest degradation affects host-parasite interactions, determining the probability of animals acquiring an infection. The activation of an immune response to fight off infections requires energy and other resources such as antioxidants which may be redirected from growth and reproduction. A key question is how selective logging—the most common form of tropical forest degradation—impacts the prevalence of avian haemosporidian infection and its correlated physiological responses (nutritional and oxidative status markers). We investigated the prevalence of Plasmodium, Haemoproteus, and Leucocytozoon parasites in 14 understorey bird species in lowland, logged and unlogged, old-growth forests of Borneo. Prevalences of infections were similar between selectively logged and unlogged forests. To explore nutritional and oxidative status effects of haemosporidian infections, we examined associations between infections and plasma proteins, plasma triglycerides, and multiple blood-based markers of oxidative status, testing for an impact of selective logging on those markers. Birds infected with Plasmodium showed higher levels of plasma proteins and non-enzymatic antioxidant capacity, and lower levels of plasma triglycerides and glutathione, compared with haemosporidian-free individuals. Conversely, birds infected with Haemoproteus showed no changes in nutritional or physiological markers compared with uninfected individuals. These results indicate higher metabolic and physiological costs of controlling Plasmodium infection, compared with Haemoproteus, possibly due to higher pathogenicity of Plasmodium. Selectively logged forests had no effect on the responses of birds to infection, suggesting that the environmental conditions of degraded forests do not appear to induce any appreciable physiological demands in parasitised birds.

The chemical properties of honey depend on the source of collection to packaging, but little is known about honey in Sabah. The aim of this study was to distinguish between the physicochemical properties and mineral content of 76 honey samples from local sources and supermarkets in Sabah, which were from contract beekeepers, unknown sources and branded honey. Raw honey was collected from contract beekeepers, while honey from unknown source was obtained from street vendors and wet markets, while branded honey was purchased from local supermarkets. The chemical parameters of the honey were assessed using established methods, while the mineral content of the honey was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Significant differences were found in several parameters measured in honey from different sources, with principal component analysis (PCA) showing clear separation between the measured parameters, yielding five factors that accounted for up to 72.25% of the total explained variance. Honey from contract beekeepers showed significant differences and higher mineral content (Ca, Cu, Fe, K, Mg, Na and Zn) compared to honey from unknown source and branded honey. Potassium was the most important element in the study with an average of 2.65 g/kg and 629.4 mg/kg for sources from contract beekeepers and branded honey, respectively. The honey from the contract beekeepers was of better quality due to its high mineral content. The results suggest that honey from contract beekeepers could be a good choice when it comes to high mineral content.Sifat kimia madu adalah bergantung kepada sumber pengumpulan hingga ke peringkat pembungkusan, namun demikian, maklumat tentang madu di Sabah kurang diketahui. Matlamat kajian ini adalah untuk membezakan antara sifat fisikokimia dan kandungan mineral bagi 76 sampel madu daripada sumber tempatan dan pasar raya di Sabah, iaitu daripada penternak lebah kontrak, sumber yang tidak diketahui dan madu berjenama. Madu mentah diperoleh daripada penternak lebah kontrak, manakala madu daripada sumber yang tidak diketahui telah diperoleh daripada peniaga jalanan dan pasar basah, manakala madu berjenama dibeli dari pasar raya tempatan. Parameter kimia madu dinilai menggunakan kaedah sedia ada yang telah ditetapkan, manakala kandungan mineral madu ditentukan menggunakan

Quaternary climate oscillations are a well-known driver of animal diversification, but their effects are most well studied in areas where glaciations lead to habitat fragmentation. In large areas of the planet, however, glaciations have had the opposite effect, but here their impacts are much less well understood. This is especially true in Southeast Asia, where cyclical changes in land distribution have generated enormous land expansions during glacial periods. In this study, we selected a panel of five songbird species complexes covering a range of ecological specificities to investigate the effects Quaternary land bridges have had on the connectivity of Southeast Asian forest biota. Specifically, we combined morphological and bioacoustic analysis with an arsenal of population genomic and modelling approaches applied to thousands of genome-wide DNA markers across a total of more than 100 individuals. Our analyses show that species dependent on forest understorey exhibit deep differentiation between Borneo and western Sundaland, with no evidence of gene flow during the land bridges accompanying the last 1-2 ice ages. In contrast, dispersive canopy species and habitat generalists have experienced more recent gene flow. Our results argue that there remains much cryptic species-level diversity to be discovered in Southeast Asia even in well-known animal groups such as birds, especially in nondispersive forest understorey inhabitants. We also demonstrate that Quaternary land bridges have not been equally suitable conduits of gene flow for all species complexes and that life history is a major factor in predicting relative population divergence time across Quaternary climate fluctuations.

Selective logging is a major driver of environmental changes in the tropics. Recently, there has been increasing interest in understanding which traits make bird species resilient or vulnerable to such changes. Physiological stress mediated by the steroid hormone corticosterone (CORT) might underlie changes in local abundance of species because it regulates a range of body functions and behaviours to maintain homeostasis in changing environments. We conducted a 3-year study to assess (a) the variation in CORT levels in feathers (where CORT is deposited during the moult) of 10 understorey bird species across both unlogged old-growth forest and selectively logged forest in Borneo, (b) how this variation is associated with within-year variation in population abundance between forest types and (c) whether the difference in feather CORT (fCORT) between co-specific populations living in unlogged and logged forests in 1 year is related with their difference in population abundance the following year. We used effect size estimates to measure standardized magnitude and direction of fCORT changes between unlogged and selectively logged forest. We found small to large effect sizes, indicating large among-species variation in physiological acclimatization to changes in forest conditions. In 2016 and 2018, species with relatively higher fCORT in unlogged forest were relatively more abundant in logged forest in the same year; in 2017, species with relatively higher fCORT in logged forest were relatively more abundant in logged forest. Importantly, we found that for a given species, the difference in fCORT at year (x) between unlogged and logged forests was negatively related with a difference in its local abundance between the two forest types in the following year (x + 1). Our results point to glucocorticoid hormones as potential mediators of carry-over effects on population abundance due to direct and indirect effects of silvicultural practices in tropical forests of Borneo, suggesting fCORT as a potential marker of population changes. A free Plain Language Summary can be found within the Supporting Information of this article.

Habitat fragmentation is a major extinction driver. Despite dramatically increasing fragmentation across the globe, its specific impacts on population connectivity across species with differing life histories remain difficult to characterize, let alone quantify. Here, we investigate patterns of population connectivity in six songbird species from Singapore, a highly fragmented tropical rainforest island. Using massive panels of genome‐wide single nucleotide polymorphisms across dozens of samples per species, we examined population genetic diversity, inbreeding, gene flow and connectivity among species along a spectrum of ecological specificities. We found a higher resilience to habitat fragmentation in edge‐tolerant and forest‐canopy species as compared to forest‐dependent understorey insectivores. The latter exhibited levels of genetic diversity up to three times lower in Singapore than in populations from contiguous forest elsewhere. Using dense genomic and geographic sampling, we identified individual barriers such as reservoirs that effectively minimize gene flow in sensitive understorey birds, revealing that terrestrial forest species may exhibit levels of sensitivity to fragmentation far greater than previously expected. This study provides a blueprint for conservation genomics at small scales with a view to identifying preferred locations for habitat corridors, flagging candidate populations for restocking with translocated individuals and improving the design of future reserves.

We assess the consequences of sustainable farming practices (“Best Management Practices”) on oil palm fruit production on 40 smallholder farms in Sabah, Malaysian Borneo, and whether maintaining vegetation cover, which is linked to environmental sustainability and higher biodiversity, results in a trade-off with oil palm production. We found considerable variation in yield among farms (6.9–37.4 t ha−1 yr−1), but little evidence for any trade-offs between yield and farming practices. This finding has important implications for livelihoods if farmers can minimize agricultural inputs, reducing costs and supporting the environmental sustainability of oil palm smallholder farms whilst maintaining crop yields.

Island biogeography is one of the most powerful subdisciplines of ecology: its mathematical predictions that island size and distance to mainland determine diversity have withstood the test of time. A key question is whether these predictions follow at a population-genomic level. Using rigorous ancient-DNA protocols, we retrieved approximately 1,000 genomic markers from approximately 100 historic specimens of two Southeast Asian songbird complexes from across the Sunda Shelf archipelago collected 1893–1957. We show that the genetic affinities of populations on small shelf islands defy the predictions of geographic distance and appear governed by Earth-historic factors including the position of terrestrial barriers (paleo-rivers) and persistence of corridors (Quaternary land bridges). Our analyses suggest that classic island-biogeographic predictors may not hold well for population-genomic dynamics on the thousands of shelf islands across the globe, which are exposed to dynamic changes in land distribution during Quaternary climate change.

This study aims to investigate the foraging behaviour of Heterotrigona itama in exploiting food resources at a residential area, and the viability of this species to adapt to urban microclimatic conditions. Heterotrigona itama prefers to forage at areas closer to their nesting site, where diverse food sources are found. The marked bees of H. itama prefer to forage on various resources available at a 500-metre radius from the house yard. The obtained results indicate that the active foraging pattern of H. itama is negatively correlated to the time phases of a day (p < 0.05). This phenomenon was contributed by the three peaks of foraging hours, which reached a peak in the early morning (6:30 to 8:00 a.m.), moderately peaked towards the evening (2:30 to 3:30 p.m.), and was greatest towards the afternoon (10:30 a.m. to 12:00 p.m.). The ambient temperature and relative humidity were not the primary factors influencing the average number of foragers exiting from and returning to the hives (temperature, p > 0.05; and humidity, p > 0.05). There was a difference between the varieties of content resources collected by the bees (p < 0.05). The nectar or water sources was the highest material (51.39%) that was brought back to the hive by foragers, followed by resin (34.73%) and pollen (13.87%). There was a significant difference in foraging time phases by returning foragers for collecting resin (p < 0.05) and nectar or water (p < 0.02), but there was no significant difference in foraging time phases found for pollen (p > 0.05). We concluded from the results that H. itama is able to withstand urban microclimate conditions, and successfully incorporated pollen, nectar or water, and resin obtained from floral and non-floral resources into their diet.

Selective logging is the main anthropogenic disturbance in tropical forests, driving shifts in species abundances. Body size and body condition are important metrics of fitness that may be affected by habitat degradation. We conducted a four-year study to investigate how selective logging impacted the body size and body condition index (BCI) of 55 Bornean bird species and whether changes in body metrics were associated with shifts in relative population abundance. Frugivorous and omnivorous birds had reduced body size in selectively logged versus unlogged forest, but we found no evidence for selective removal of individuals driven by sex differences or post-fledging body size, indicating different developmental conditions for frugivores and omnivores in logged forest. Change in body size between forest types showed no clear patterns for insectivorous birds, and did not differ between IUCN categories. BCI of birds was affected by study year, suggesting an effect of climatic conditions on food availability, but not by logging. At the community level, post-logging change in population abundance was not associated with reduced body size, although between species variation suggests that adverse environmental conditions and different coping strategies underlie body size reductions in logged forest. Our study suggests that body size is a valuable metric to assess how logging impacts forest birds, pointing towards potential functional consequences related to seed dispersal within logged forests and need for improved silvicultural practices.

Widespread selective logging in tropical forest causes structural damage and associated shifts in species composition, but we lack understanding of how selective logging impacts mechanistic processes that drive these biodiversity changes. Movement is a vital mechanistic process underpinning demographic, ecological, and evolutionary processes that likely determine species responses to logging. We assessed how tropical selective logging impacts local movements of 71 understory avian species in Sabah, Malaysian Borneo, and determined whether movement patterns relate to species' conservation status, functional traits, sensitivity to logging and trophic position. We used a capture-mark-recapture methodology and a hierarchical Bayesian framework to model maximum observed local movement distances, accounting for spatial sampling heterogeneity. Across the avian community, we found a higher probability of moving shorter distances (up to 200 m) in logged forests, and higher movement probability at longer distances (above 200 m) in unlogged forests. Altered movement patterns after logging may reflect increased understory density, changed resource distribution and/or predation risks, and suggest smaller home-range sizes. Species' conservation status, body mass, foraging guild, logging sensitivity and trophic position were unrelated to the magnitude of movement change. The continued persistence of understory species in our sample after selective logging may depend on flexibility in movement behaviour, conferring resilience to habitat degradation and the retention of high conservation values. This lends further support for the protection of these logged forests for biodiversity conservation.

Maintaining forest conservation set-asides is a key criterion of sustainability certification of many crops that drive tropical deforestation, but their value for carbon storage and associated biodiversity is unclear. We conducted vegetation measurements to examine the benefits of set-asides for aboveground carbon stocks (AGC) in certified oil palm plantations on Borneo, and whether their AGC is positively associated with plant diversity. The mean estimated AGC of live trees and palms ≥10 cm diameter in set-asides in certified oil palm plantations (52.8 Mg ha−1) was >1.5-times that of oil palm (30.3 Mg ha−1), with some plots supporting similar AGC to primary forest. For lowland Borneo, we estimate that the average AGC of oil palm plantations with 10% coverage of set-asides is up to 20% greater than the average AGC of oil palm plantations without set-asides, newly demonstrating carbon storage as a benefit of conservation set-asides. We found positive relationships between AGC and plant diversity, highlighting the carbon–biodiversity co-benefits of set-asides. However, set-asides had a lower density of tree seedlings than continuous primary forest, indicating potential suppression of future tree regeneration and AGC. Our findings support the application of zero-deforestation during agricultural development, to conserve areas of remaining forest with high AGC and high biodiversity. We recommend management practices that boost regeneration in existing set-asides (e.g. enrichment planting), which would be most effective in larger set-asides, and could substantially increase the AGC of agricultural landscapes without removing land from production, and help conserve forest-dependent biodiversity.

Rain forests on Borneo support exceptional concentrations of endemic insect biodiversity, but many of these forest‐dependent species are threatened by land‐use change. Totally protected areas (TPAs) of forest are key for conserving biodiversity, and we examined the effectiveness of the current TPA network for conserving range‐restricted butterflies in Sabah (Malaysian Borneo). We found that mean diurnal temperature range and precipitation of the wettest quarter of the year were the most important predictors of butterfly distributions (N = 77 range‐restricted species), and that species richness increased with elevation and aboveground forest carbon. On average across all species, TPAs were effective at conserving ~43% of species’ ranges, but encompassed only ~40% of areas with high species richness (i.e., containing at least 50% of our study species). The TPA network also included only 33%–40% of areas identified as high priority for conserving range‐restricted species, as determined by a systematic conservation prioritization analysis. Hence, the current TPA network is reasonably effective at conserving range‐restricted butterflies, although considerable areas of high species richness (6,565 km2) and high conservation priority (11,152–12,531 km2) are not currently protected. Sabah's remaining forests, and the range‐restricted species they support, are under continued threat from agricultural expansion and urban development, and our study highlights important areas of rain forest that require enhanced protection. Abstract in Malay is available with online material.

Selective logging is the dominant form of human disturbance in tropical forests, driving changes in the abundance of vertebrate and invertebrate populations relative to undisturbed old‐growth forests. A key unresolved question is understanding which physiological mechanisms underlie different responses of species and functional groups to selective logging. Regulation of oxidative status is thought to be one major physiological mechanism underlying the capability of species to cope with environmental changes. Using a correlational cross‐sectional approach, we compared a number of oxidative status markers among 15 understorey bird species in unlogged and selectively logged forest in Borneo in relation to their feeding guild. We then tested how variation of markers between forest types was associated with that in population abundance. Birds living in logged forests had a higher activity of the antioxidant enzyme superoxide dismutase and a different regulation of the glutathione cycle compared to conspecific birds in unlogged forest. However, neither oxidative damage nor oxidized glutathione differed between forest types. We also found that omnivores and insectivores differed significantly in all markers related to the key cellular antioxidant glutathione irrespective of the forest type. Species with higher levels of certain antioxidant markers in a given type of forest were less abundant in that forest type compared to the other. Our results suggest that there was little long‐term effect of logging (last logging rotation occurred ~15 years prior to the study) on the oxidative status of understorey bird species. However, it is unclear if this was owing to plasticity or evolutionary change. Our correlative results also point to a potential negative association between some antioxidants and population abundance irrespective of the forest type.

Habitat destruction and degradation are major drivers of biodiversity loss and attention is increasingly focused on how different traits of species affect their vulnerability. Dietary traits are critical in this respect, and are typically examined by assigning species to different feeding and foraging guilds. However, such guilds may mask large variation in species’ trophic interactions, limiting our understanding of species’ responses. Here we use stable isotopes to quantify trophic positions within a Family of insectivorous understory birds, the Timaliidae (babblers), within Bornean rainforests. We then relate changes in species’ abundances following intensive selective logging of forest to their trophic positions, body sizes and foraging heights. We found that trophic positions within this single feeding guild spanned more than an entire trophic level. Moreover, changes in abundance following logging were significantly and independently related to mean trophic position in primary forest, body size and foraging height: large ground-feeding species occupying high trophic positions were more adversely affected than small understory-feeders with lower trophic positions. These three variables together explained 81% of the variance in species’ responses to logging. The single most important predictor, however, was a species’ mean trophic position. Species recorded in both habitats also had significantly higher trophic positions in logged forest. These data provide critical new understanding of species’ responses to disturbance. They also indicate previously unrecognised functional changes to species assemblages following logging, highlighting the importance of numerical assessments of trophic position within individual feeding guilds.

Tropical rainforests are subject to extensive degradation by commercial selective logging. Despite pervasive changes to forest structure, selectively logged forests represent vital refugia for global biodiversity. The ability of these forests to buffer temperature-sensitive species from climate warming will be an important determinant of their future conservation value, although this topic remains largely unexplored. Thermal buffering potential is broadly determined by: (i) the difference between the "macroclimate" (climate at a local scale, m to ha) and the "microclimate" (climate at a fine-scale, mm to m, that is distinct from the macroclimate); (ii) thermal stability of microclimates (e.g. variation in daily temperatures); and (iii) the availability of microclimates to organisms. We compared these metrics in undisturbed primary forest and intensively logged forest on Borneo, using thermal images to capture cool microclimates on the surface of the forest floor, and information from dataloggers placed inside deadwood, tree holes and leaf litter. Although major differences in forest structure remained 9-12 years after repeated selective logging, we found that logging activity had very little effect on thermal buffering, in terms of macroclimate and microclimate temperatures, and the overall availability of microclimates. For 1°C warming in the macroclimate, temperature inside deadwood, tree holes and leaf litter warmed slightly more in primary forest than in logged forest, but the effect amounted to0.1°C difference between forest types. We therefore conclude that selectively logged forests are similar to primary forests in their potential for thermal buffering, and subsequent ability to retain temperature-sensitive species under climate change. Selectively logged forests can play a crucial role in the long-term maintenance of global biodiversity.

Strong global demand for tropical timber and agricultural products has driven large-scale logging and subsequent conversion of tropical forests. Given that the majority of tropical landscapes have been or will likely be logged, the protection of biodiversity within tropical forests thus depends on whether species can persist in these economically exploited lands, and if species cannot persist, whether we can protect enough primary forest from logging and conversion. However, our knowledge of the impact of logging and conversion on biodiversity is limited to a few taxa, often sampled in different locations with complex land-use histories, hampering attempts to plan cost-effective conservation strategies and to draw conclusions across taxa. Spanning a land-use gradient of primary forest, once- and twice-logged forests, and oil palm plantations, we used traditional sampling and DNA metabarcoding to compile an extensive data set in Sabah, Malaysian Borneo for nine vertebrate and invertebrate taxa to quantify the biological impacts of logging and oil palm, develop cost-effective methods of protecting biodiversity, and examine whether there is congruence in response among taxa. Logged forests retained high species richness, including, on average, 70% of species found in primary forest. In contrast, conversion to oil palm dramatically reduces species richness, with significantly fewer primary-forest species than found on logged forest transects for seven taxa. Using a systematic conservation planning analysis, we show that efficient protection of primary-forest species is achieved with land portfolios that include a large proportion of logged-forest plots. Protecting logged forests is thus a cost-effective method of protecting an ecologically and taxonomically diverse range of species, particularly when conservation budgets are limited. Six indicator groups (birds, leaf-litter ants, beetles, aerial hymenopterans, flies, and true bugs) proved to be consistently good predictors of the response of the other taxa to logging and oil palm. Our results confidently establish the high conservation value of logged forests and the low value of oil palm. Cross-taxon congruence in responses to disturbance also suggests that the practice of focusing on key indicator taxa yields important information of general biodiversity in studies of logging and oil palm.

In view of the rapid rate of expansion of agriculture in tropical regions, attention has focused on the potential for privately-managed rainforest patches within agricultural land to contribute to biodiversity conservation. However, these sites generally differ in their history of forest disturbance and management compared with other forest fragments, and more information is required on the biodiversity value of these privately-managed sites, particularly in oil-palm dominated landscapes of SE Asia. Here we address this issue, using tropical leaf-litter ants in rainforest fragments surrounded by mature oil palm plantations in Sabah, Borneo as a model system. We compare the species richness and composition of ant assemblages in privately-managed forest fragments ('high conservation value' fragments; HCVs) with those in publically-managed fragments of forest (virgin jungle reserves; VJRs) and control sites in extensive tracts of primary forest. In this way, we test the hypothesis that privately-managed and publically-managed forest fragments differ in their species richness and composition as a result of differences in history and management and hence in habitat quality. In support of this hypothesis, we found that HCVs had much poorer habitat quality than VJRs, including lower sizes and densities of trees, less canopy cover, fewer dipterocarp trees and shallower leaf litter. Consequently, HCVs supported only half the species richness of ants in VJRs, which in turn supported 70 % of the species richness of control sites, with vegetation structure and composition explaining 77 % of the variation among forest fragments in ant species richness. HCVs were also much smaller than VJRs but there was only a weak relationship between fragment size and habitat quality, and species richness was not related to fragment size. VJRs supported 78 % of the 156 species found in extensive tracts of forest whereas HCVs supported only 22 %, which was only slightly higher than the proportion previously recorded in oil palm (19 %). These data support previous findings that publically-managed VJR fragments can make an important contribution to biodiversity conservation within agricultural landscapes. However, we suggest that for these HCVs to be effective as reservoirs of biodiversity, management is required to restore vegetation structure and habitat quality, for instance through enrichment planting with native tree species. © 2014 Springer Science+Business Media Dordrecht.

Forests in Southeast Asia are rapidly being logged and converted to oil palm. These changes in land-use are known to affect species diversity but consequences for the functional diversity of species assemblages are poorly understood. Environmental filtering of species with similar traits could lead to disproportionate reductions in trait diversity in degraded habitats. Here, we focus on dung beetles, which play a key role in ecosystem processes such as nutrient recycling and seed dispersal. We use morphological and behavioural traits to calculate a variety of functional diversity measures across a gradient of disturbance from primary forest through intensively logged forest to oil palm. Logging caused significant shifts in community composition but had very little effect on functional diversity, even after a repeated timber harvest. These data provide evidence for functional redundancy of dung beetles within primary forest and emphasize the high value of logged forests as refugia for biodiversity. In contrast, conversion of forest to oil palm greatly reduced taxonomic and functional diversity, with a marked decrease in the abundance of nocturnal foragers, a higher proportion of species with small body sizes and the complete loss of telecoprid species (dung-rollers), all indicating a decrease in the functional capacity of dung beetles within plantations. These changes also highlight the vulnerability of community functioning within logged forests in the event of further environmental degradation.

Effects of logging on species composition in tropical rainforests are well known but may fail to reveal key changes in species interactions. We used nitrogen stable-isotope analysis of 73 species of understory birds to quantify trophic responses to repeated intensive logging of rainforest in northern Borneo and to test 4 hypotheses: logging has significant effects on trophic positions and trophic-niche widths of species, and the persistence of species in degraded forest is related to their trophic positions and trophic-niche widths in primary forest. Species fed from higher up the food chain and had narrower trophic-niche widths in degraded forest. Species with narrow trophic-niche widths in primary forest were less likely to persist after logging, a result that indicates a higher vulnerability of dietary specialists to local extinction following habitat disturbance. Persistence of species in degraded forest was not related to a species' trophic position. These results indicate changes in trophic organization that were not apparent from changes in species composition and highlight the importance of focusing on trophic flexibility over the prevailing emphasis on membership of static feeding guilds. Our results thus support the notion that alterations to trophic organization and interactions within tropical forests may be a pervasive and functionally important hidden effect of forest degradation.

Background Malaria cases caused by Plasmodium knowlesi, a simian parasite naturally found in long-tailed and pig-tailed macaques, are increasing rapidly in Sabah, Malaysia. One hypothesis is that this increase is associated with changes in land use. A study was carried out to identify the anopheline vectors present in different forest types and to observe the human landing behaviour of mosquitoes. Methods Mosquito collections were carried out using human landing catches at ground and canopy levels in the Tawau Division of Sabah. Collections were conducted along an anthropogenic disturbance gradient (primary forest, lightly logged virgin jungle reserve and salvage logged forest) between 18:00 and 22:00 h. Results Anopheles balabacensis, a vector of P. knowlesi, was the predominant species in all collection areas, accounting for 70 % of the total catch, with a peak landing time of 18:30–20:00 h. Anopheles balabacensis had a preference for landing on humans at ground level compared to the canopy (p

Selective logging is one of the major drivers of tropical forest degradation, causing important shifts in species composition. Whether such changes modify interactions between species and the networks in which they are embedded remain fundamental questions to assess the ‘health’ and ecosystem functionality of logged forests. We focus on interactions between lianas and their tree hosts within primary and selectively logged forests in the biodiversity hotspot of Malaysian Borneo. We found that lianas were more abundant, had higher species richness, and different species compositions in logged than in primary forests. Logged forests showed heavier liana loads disparately affecting slow-growing tree species, which could exacerbate the loss of timber value and carbon storage already associated with logging. Moreover, simulation scenarios of host tree local species loss indicated that logging might decrease the robustness of liana–tree interaction networks if heavily infested trees (i.e. the most connected ones) were more likely to disappear. This effect is partially mitigated in the short term by the colonization of host trees by a greater diversity of liana species within logged forests, yet this might not compensate for the loss of preferred tree hosts in the long term. As a consequence, species interaction networks may show a lagged response to disturbance, which may trigger sudden collapses in species richness and ecosystem function in response to additional disturbances, representing a new type of ‘extinction debt’., A.M. was funded by a Basque Government postdoctoral fellowship and an ETH postdoctoral fellowship. Field research support was provided by an ARC Laureate awarded to W.F.L.

Large areas of tropical forest now exist as remnants scattered across agricultural landscapes, and so understanding the impacts of forest fragmentation is important for biodiversity conservation. We examined species richness and nestedness among tropical forest remnants in birds (meta-analysis of published studies) and insects (field data for fruit-feeding Lepidoptera (butterflies and moths) and ants). Species–area relationships were evident in all four taxa, and avian and insect assemblages in remnants typically were nested subsets of those in larger areas. Avian carnivores and nectarivores and predatory ants were more nested than other guilds, implying that the sequential loss of species was more predictable in these groups, and that fragmentation alters the trophic organization of communities. For butterflies, the ordering of fragments to achieve maximum nestedness was by fragment area, suggesting that differences among fragments were driven mainly by extinction. In contrast for moths, maximum nestedness was achieved by ordering species by wing length; species with longer wings (implying better dispersal) were more likely to occur at all sites, including low diversity sites, suggesting that differences among fragments were driven more strongly by colonization. Although all four taxa exhibited high levels of nestedness, patterns of species turnover were also idiosyncratic, and thus even species-poor sites contributed to landscape-scale biodiversity, particularly for insects.

Aim To estimate whether species have shifted at equal rates at their leading edges (cool boundaries) and trailing edges (warm boundaries) in response to climate change. We provide the first such evidence for tropical insects, here examining elevation shifts for the upper and lower boundaries shifts of montane moths. Threats to species on tropical mountains are considered.Location Mount Kinabalu, Sabah, Malaysia.Methods We surveyed Lepidoptera (Geometridae) on Mount Kinabalu in 2007, 42 years after the previous surveys in 1965. Changes in species upper and lower boundaries, elevational extents and range areas were assessed. We randomly subsampled the data to ensure comparable datasets between years. Estimated shifts were compared for endemic versus more widespread species, and for species that reached their range limits at different elevations.Results Species that reached their upper limits at 2500-2700 m (n= 28 species, 20% of those considered) retreated at both their lower and upper boundaries, and hence showed substantial average range contractions (-300 m in elevational extent and -45 km2 in estimated range area). These declines may be associated with changes in cloud cover and the presence of ecological barriers (geological and vegetation transitions) which impede uphill movement. Other than this group, most species (n= 109, 80% of the species considered) expanded their upper boundaries upwards (by an average of 152 m) more than they retreated at their lower boundaries (77 m).Main conclusions Without constraints, leading margins shifted uphill faster than trailing margins retreated, such that many species increased their elevational extents. However, this did not result in increases in range area because the area of land available declines with increasing elevation. Species close to a major ecological/geological transition zone on the mountain flank declined in their range areas. Extinction risk may increase long before species reach the summit, even when undisturbed habitats are available.

Many areas of rain forest now exist as habitat fragments, and understanding the impacts of fragmentation is important for determining the viability of populations within forest remnants. We investigated impacts of forest fragmentation on genetic diversity in the butterfly Mycalesis orseis (Satyrinae) in Sabah (Malaysian Borneo). We investigated mtDNA diversity in 90 individuals from ten forest sites typical of the sizes of forest remnants that currently exist in the region. Nucleotide diversity declined with increasing isolation of remnants, but there was no effect of remnant size or population size, and haplotype diversity was similar among sites. Thus, approximately 50 y after forest fragmentation, few changes in genetic diversity were apparent and remnants apparently supported genetically viable populations of this butterfly. Many studies have shown that responses of species to habitat fragmentation usually follow a time delay, and so we developed a Monte Carlo simulation model to investigate changes in genetic diversity over time in small remnants. Model output indicated a substantial time delay (> 100 y) between fragmentation and genetic erosion, suggesting that, in the smallest study remnants, an increased risk of extinction from reduced genetic diversity is likely in the longer term.

Invertebrates are dominant species in primary tropical rainforests, where their abundance and diversity contributes to the functioning and resilience of these globally important ecosystems. However, more than one-third of tropical forests have been logged, with dramatic impacts on rainforest biodiversity that may disrupt key ecosystem processes. We find that the contribution of invertebrates to three ecosystem processes operating at three trophic levels (litter decomposition, seed predation and removal, and invertebrate predation) is reduced by up to one-half following logging. These changes are associated with decreased abundance of key functional groups of termites, ants, beetles and earthworms, and an increase in the abundance of small mammals, amphibians and insectivorous birds in logged relative to primary forest. Our results suggest that ecosystem processes themselves have considerable resilience to logging, but the consistent decline of invertebrate functional importance is indicative of a human-induced shift in how these ecological processes operate in tropical rainforests., Invertebrates are key components in the ecological functioning of tropical forests. Here, Ewers et al. show that, compared to primary forest, logging halves the contribution of invertebrate species to several key ecosystem processes, including litter decomposition.

Summary 1 Widespread and rapid losses of tropical rain forests have made understanding the responses of species to rain forest fragmentation an area of major concern. In this study we examined the impacts of habitat fragmentation on the species richness and faunal composition of butterflies in tropical rain forests in Sabah, Borneo. We analysed patterns of both α- and β-diversity to assess the relative importance of differences in patch size, isolation and vegetation structure on the diversity and similarity of species assemblages. We used additive partitioning to assess the relative contributions of intact forest and forest remnants to overall species richness at a landscape scale and we examined which traits of species best predicted their responses to fragmentation. 2 Species richness and diversity in rain forest remnants was significantly positively related to remnant size and significantly negatively related to isolation, in keeping with theories of island biogeography. Species assemblages at different sites were significantly nested, with those species most adversely affected by forest fragmentation having a narrow range of larval host-plants and, to a lesser extent, being large-bodied. No species endemic to Borneo was recorded in forest remnants smaller than 4000 ha, but even the smallest remnant (120 ha) supported species with geographical distributions confined within Sundaland (West Malaysia and the islands of the Sunda Shelf). 3 Although assemblages were significantly nested, they departed substantially from perfect nestedness, with some species recorded only or predominantly in small, relatively depauperate remnants. As a result there was substantial β-diversity among sites, which was related to variation in both fragment size and vegetation structure. At the landscape scale, diversity within sites was less than that between sites, and the majority of the diversity between sites was related to variation in fragment size. 4 Synthesis and applications. Substantial diversity was added to the assemblage of butterflies in Bornean rain forests by virtue of species differences among fragments, which were related mainly to differences in patch size and vegetation structure. The data reported indicate that, despite having lower species richness, relatively small and isolated remnants of rain forest make a substantial contribution to regional diversity. Small isolated forest remnants are generally accorded low conservation status and given little protection, with the result that they often disappear over time because of continued anthropogenic disturbance. The results of this study indicate that the conservation value of small remnants of forest, in particular their contribution to environmental heterogeneity, should not be overlooked.

Tropical rain forests are well known as centres of insect diversity and much effort has focused on the role of larval host plant specificity in generating and maintaining this diversity, but fewer studies have examined the exploitation of different food resources by adults in this context. Tropical butterflies feed as adults on a wide range of resources and we examined the diversity and ecology of species feeding on rotting fruit and carrion in a tropical lowland rain forest in Sabah, Borneo. We found that species richness and diversity were significantly higher on carrion than on fruit, and that this pattern was repeated at genus and family level. There was little similarity in species assemblages on the two substrates and β-diversity between carrion and fruit comprised 33% of the total diversity of butterflies feeding on decaying matter. β-diversity between canopy gap and shade microhabitats comprised 21% of total species diversity on carrion but only 7% of the total on fruit, indicating greater functional diversity on carrion in terms of light preferences. Captures were strongly male-biased on carrion but not on fruit, and recapture rates were much lower on carrion than on fruit. Species from two subfamilies (Nymphalinae and Charaxinae) exploited both substrates and for Charaxinae, there was evidence from adult flight morphology that species on carrion were capable of faster more-powerful flight. These results support the notion of a distinctive carrion-feeding fauna comprising more mobile species, which may use carrion to meet additional nitrogen requirements resulting from greater musculature. However there was no relationship between flight morphology and substrate choice in the Nymphalinae, and carrion-feeding may not have a unitary explanation.

We used traps baited with fruit to examine how the temporal variation of butterflies within primary forest in Sabah, Borneo differed between species. In addition, we compared patterns of temporal variation in primary and selectively logged forest, and we tested the hypothesis that selective logging has different recorded impacts on species diversity of adults during the wet monsoon period and the drier remaining half of the year. Species of Satyrinae and Morphinae had significantly less-restricted flight periods than did species of Nymphalinae and Charaxinae, which were sampled mainly during the drier season, especially in primary forest. Species diversity of adults was significantly higher during the drier season in primary forest, but did not differ between seasons in logged forest. As a consequence, logging had opposite recorded impacts on diversity during wetter and drier seasons: primary forest had significantly higher diversity than logged forest during the drier season but significantly lower diversity than logged forest during the wetter monsoon season. The results of this study have important implications for the assessment of biodiversity in tropical rain forests, particularly in relation to habitat disturbance: short-term assessments that do not take account of seasonal variation in abundance are likely to produce misleading results, even in regions where the seasonal variation in rainfall is not that great.

1. The impacts of habitat disturbance on biodiversity within tropical forests are an area of current concern but are poorly understood and difficult to predict. This is due in part to a poor understanding of how species respond to natural variation in environmental conditions within primary forest and how these conditions alter following anthropogenic disturbance. Within this context, the main aim of this study was to test the hypothesis that the gap and shade preferences of fruit-feeding butterflies in primary forest in northern Borneo can be used to predict species' responses to selective logging and thus explain changes in diversity and geographical distinctness in relation to habitat disturbance. 2. Overall, there was little difference in butterfly diversity between primary forest and forest that had been selectively logged 10-12 years previously. In contrast, there were marked differences in the composition of the butterfly assemblages in the two habitats, which were strongly associated with species' gap preferences and geographical distributions. In Satyrinae and Morphinae, those species with higher shade preferences and narrower geographical distributions were most adversely affected by logging, whereas cosmopolitan species with high light preferences benefited from logging. In Nymphalinae and Charaxinae the opposite was observed: those species with wider geographical distributions were adversely affected and those species with relatively restricted distributions were more common in logged forest. 3. These changes in butterfly assemblages were associated with changes in vegetation structure following selective logging, which resulted in much lower habitat heterogeneity with less dense shade and fewer open gaps in logged forest. Areas of dense shade, which were more common in unlogged forest, supported species of Satyrinae and Morphinae with restricted geographical distributions, whereas open gaps, which were also more common in unlogged forest, attracted widespread species of Nymphalinae and Charaxinae. These butterfly-habitat associations in primary forest explain the opposite responses of the two groups of butterflies to selective logging. 4. Synthesis and applications. This study highlights the need to sample at a sufficiently large spatial scale to account for impacts of disturbance on heterogeneity in forest environments. It also demonstrates how understanding the responses of species to natural variation in environmental conditions within undisturbed forest is crucial to interpreting responses of species to anthropogenic habitat modification. The results further indicate that selectively logged forests can make an important contribution to the conservation of tropical biodiversity, provided that they are managed in a way that maintains environmental heterogeneity.

Strong global demand for tropical timber and agricultural products has driven large-scale logging and subsequent conversion of tropical forests. Given that the majority of tropical landscapes have been or will likely be logged, the protection of biodiversity within tropical forests thus depends on whether species can persist in these economically exploited lands, and if species cannot persist, whether we can protect enough primary forest from logging and conversion. However, our knowledge of the impact of logging and conversion on biodiversity is limited to a few taxa, often sampled in different locations with complex land-use histories, hampering attempts to plan cost-effective conservation strategies and to draw conclusions across taxa. Spanning a land-use gradient of primary forest, once- and twice-logged forests, and oil palm plantations, we used traditional sampling and DNA metabarcoding to compile an extensive data set in Sabah, Malaysian Borneo for nine vertebrate and invertebrate taxa to quantify the biological impacts of logging and oil palm, develop cost-effective methods of protecting biodiversity, and examine whether there is congruence in response among taxa. Logged forests retained high species richness, including, on average, 70% of species found in primary forest. In contrast, conversion to oil palm dramatically reduces species richness, with significantly fewer primary-forest species than found on logged forest transects for seven taxa. Using a systematic conservation planning analysis, we show that efficient protection of primary-forest species is achieved with land portfolios that include a large proportion of logged-forest plots. Protecting logged forests is thus a cost-effective method of protecting an ecologically and taxonomically diverse range of species, particularly when conservation budgets are limited. Six indicator groups (birds, leaf-litter ants, beetles, aerial hymenopterans, flies, and true bugs) proved to be consistently good predictors of the response of the other taxa to logging and oil palm. Our results confidently establish the high conservation value of logged forests and the low value of oil palm. Cross-taxon congruence in responses to disturbance also suggests that the practice of focusing on key indicator taxa yields important information of general biodiversity in studies of logging and oil palm.