Bornean Rain Forest Research Articles

Biodiversity Assessment in Incomplete Inventories: Leaf Litter Ant Communities in Several Types of Bornean Rain Forest

Biodiversity assessment of tropical taxa is hampered by their tremendous richness, which leads to large numbers of singletons and incomplete inventories in survey studies. Species estimators can be used for assessment of alpha diversity, but calculation of beta diversity is hampered by pseudo-turnover of species in undersampled plots. To assess the impact of unseen species, we investigated different methods, including an unbiased estimator of Shannon beta diversity that was compared to biased calculations. We studied alpha and beta diversity of a diverse ground ant assemblage from the Southeast Asian island of Borneo in different types of tropical forest: diperocarp forest, alluvial forest, limestone forest and heath forests. Forests varied in plant composition, geology, flooding regimes and other environmental parameters. We tested whether forest types differed in species composition and if species turnover was a function of the distance between plots at different spatial scales. As pseudo-turnover may bias beta diversity we hypothesized a large effect of unseen species reducing beta diversity. We sampled 206 ant species (25% singletons) from ten subfamilies and 55 genera. Diversity partitioning among the four forest types revealed that whereas alpha species richness and alpha Shannon diversity were significantly smaller than expected, beta-diversity for both measurements was significantly higher than expected by chance. This result was confirmed when we used the unbiased estimation of Shannon diversity: while alpha diversity was much higher, beta diversity differed only slightly from biased calculations. Beta diversity as measured with the Chao-Sørensen or Morisita-Horn Index correlated with distance between transects and between sample points, indicating a distance decay of similarity between communities. We conclude that habitat heterogeneity has a high influence on ant diversity and species turnover in tropical sites and that unseen species may have only little impact on calculation of Shannon beta diversity when sampling effort has been high.

Effects of a Fern-Dwelling Ant Species, Crematogaster difformis, on the Ant Assemblages of Emergent Trees in a Bornean Tropical Rainforest

Abstract This study examined the effects of a fern-dwelling ant species, Crematogaster difformis Smith (Formicidae, Hymenoptera), which defends territories in large areas of the crowns of emergent trees, on the composition and spatial distribution of other ant species on the trees in a Bornean tropical rainforest. We investigated the within-tree distribution of nest sites and foraging areas of individual ant colonies on emergent trees. The ant species composition on trees occupied by C. difformis was significantly different from that on conspecific trees without C. difformis. The species richness of ants inhabiting emergent trees, colony abundance of ants that nested and foraged in the crowns, and colony abundance of ants that nested on and in the ground but foraged in the crowns were all significantly lower on trees occupied by C. difformis than on conspecific trees without C. difformis. These results suggest that C. difformis suppresses the distribution of other ant species on emergent trees by excluding them from C. difformis territories and that a single ant species can affect the structure of the entire ant assemblage in the canopy of tropical rainforests.

Bacterial community structure of contrasting soils underlying Bornean rain forests: Inferences from microarray and next-generation sequencing methods

Soil microbial diversity is vast, and we lack even basic understanding of how this diversity is distributed ecologically. Using pyrosequencing and microarray methods, we quantified the structure of bacterial communities in two contrasting soils underlying Bornean rain forest (clay and sandy loam) that differ markedly in soil properties, aboveground tree flora, and leaf litter decomposition rates. We found significant soil-related taxonomic and phylogenetic differences between communities that, due to their proximity, are independent of climate. Bacterial communities showed distinct compositional and taxon-abundance distributions that were significantly correlated with the structure of the overlying tree community. Richness of bacteria was greater in the more resource-rich clay soil. Phylogenetic community analyses suggested that environmental filtering may be an important mechanism of community assembly in clay, compared to niche-competition in sandy loam. The Acidobacteria were the most abundant group in clay, but the Proteobacteria dominated in sandy loam. Of the ten most abundant classes, the Actinobacteria, Betaproteobacteria, Clostridia, Bacilli, and Gammaproteobacteria were more abundant in sandy loam than clay. Our study, which is the first to quantify edaphic variation in bacterial communities using high-throughput methods in soils underlying one of the most tree species rich forests on Earth, indicates an important role of plant–soil feedbacks linking the community structure of the trees and the underlying soil microbiome. We suggest the biochemical composition of carbon and nutrient resources in plant litter and soil pH and oxygen availability as important determinants of the distribution of bacterial diversity.

Seasonality in phytophagous scarabaeid (Melolonthinae and Rutelinae) abundances in an ‘aseasonal’ Bornean rainforest

Abstract. 1. Seasonal patterns in insect population fluctuations have rarely been examined in rainforests of the central part of Southeast Asia where the climate is aseasonal.2. We examined the seasonality of population fluctuations in a Bornean rainforest phytophagous scarabaeid assemblage (six species of Melolonthinae and seven of Rutelinae). We also investigated effects on abundances of these insects of irregularly fluctuating environmental changes, such as short‐term rainfall, and community‐level leaf flushing and flowering of canopy trees. Scarabaeids were collected over 6 years by monthly light‐trapping.3. Eight scarabaeid species had clear seasonality in occurrence and abundance. Seasonal trends were synchronised across the eight species; their monthly catches peaked from March to May and were nearly zero in other months. An analysis of correlations between environmental changes and insect abundances suggested that short‐term changes in rainfall affected the synchrony.4. In contrast, fluctuations in abundances of five other scarabaeid species were unrelated to calendar seasons. In one of the five scarabaeids, which is a flower‐visiting species, the patterns in population fluctuation strongly correlated with flowering changes. In the remaining four species, no correlations were observed between environmental changes and population fluctuation patterns.5. While previous studies have demonstrated that aseasonal patterns in population fluctuations are common in various insect assemblages in Southeast Asian rainforests, we show that clear seasonality is prevalent for the phytophagous scarabaeid assemblage.

Light‐based Regeneration Niches: Evidence from 21 Dipterocarp Species using Size‐specific RGRs

AbstractA continuing challenge in tropical ecology is to explain the coexistence of large numbers of rain forest tree species. One possible coexistence mechanism is partitioning of the highly variable and dynamic forest light environment, in which species that grow better in one light treatment grow worse in another. To test whether species respond differently to the light environment, we estimated growth rates of 21 Dipterocarpaceae species from Malaysian Borneo grown in shade houses for 2 yr in three light treatments (0.3%, 3%, and 18% full sunlight). We made regular measurements of height, diameter, and aboveground biomass, enabling us to calculate growth rates for each response. We estimated size‐specific growth rates using nonlinear mixed‐effects models, as average relative growth rate was strongly size dependent. For all species, the greatest diameter growth rate was achieved in 18 percent full sunlight, whereas for five of the twenty‐one species, the greatest height growth rate was achieved in three percent full sunlight. We investigated correlations among growth rates in different light treatments, but no negative correlations were found, indicating that species growing well in one light treatment did not grow poorly in the others. There were substantial crossovers, however, in species ranks among the three light treatments, indicating that there was no single growth rate hierarchy common to all light treatments. The lack of a single consistent growth hierarchy across light treatments indicates that heterogeneity in the forest light environment could contribute to the maintenance of the diversity of Dipterocarpaceae found in lowland Bornean rain forests via light‐based regeneration niches.

The atmospheric chemistry of trace gases and particulate matter emitted by different land uses in Borneo

We report measurements of atmospheric composition over a tropical rainforest and over a nearby oil palm plantation in Sabah, Borneo. The primary vegetation in each of the two landscapes emits very different amounts and kinds of volatile organic compounds (VOCs), resulting in distinctive VOC fingerprints in the atmospheric boundary layer for both landscapes. VOCs over the Borneo rainforest are dominated by isoprene and its oxidation products, with a significant additional contribution from monoterpenes. Rather than consuming the main atmospheric oxidant, OH, these high concentrations of VOCs appear to maintain OH, as has been observed previously over Amazonia. The boundary-layer characteristics and mixing ratios of VOCs observed over the Borneo rainforest are different to those measured previously over Amazonia. Compared with the Bornean rainforest, air over the oil palm plantation contains much more isoprene, monoterpenes are relatively less important, and the flower scent, estragole, is prominent. Concentrations of nitrogen oxides are greater above the agro-industrial oil palm landscape than over the rainforest, and this leads to changes in some secondary pollutant mixing ratios (but not, currently, differences in ozone). Secondary organic aerosol over both landscapes shows a significant contribution from isoprene. Primary biological aerosol dominates the super-micrometre aerosol over the rainforest and is likely to be sensitive to land-use change, since the fungal source of the bioaerosol is closely linked to above-ground biodiversity.

Fine‐scale Spatial Genetic Structure of Ten Dipterocarp Tree Species in a Bornean Rain Forest

AbstractFine‐scale spatial genetic structure is increasingly recognized as an important factor in the studies of tropical forest trees as it influences genetic diversity of local populations. The biologic mechanisms that generate fine‐scale spatial genetic structure are not fully understood. We studied fine‐scale spatial genetic structure in ten coexisting dipterocarp tree species in a Bornean rain forest using microsatellite markers. Six of the ten species showed statistically significant fine‐scale spatial genetic structure. Fine‐scale spatial genetic structure was stronger at smaller spatial scales (≤ 100 m) than at larger spatial scales (> 100 m) for each species. Multiple regression analysis suggested that seed dispersal distance was important at the smaller spatial scale. At the larger scale (> 100 m) and over the entire sample range (0–1000 m), pollinators and spatial distribution of adult trees were more important determinants of fine‐scale spatial genetic structure. Fine‐scale spatial genetic structure was stronger in species pollinated by less mobile small beetles than in species pollinated by the more mobile giant honeybee (Apis dorsata). It was also stronger in species where adult tree distributions were more clumped. The hypothesized mechanisms underlying the negative correlation between clump size and fine‐scale spatial genetic structure were a large overlap among seed shadows and genetic drift within clumped species.

Size-resolved aerosol water uptake and cloud condensation nuclei measurements as measured above a Southeast Asian rainforest during OP3

Abstract. The influence of the properties of fine particles on the formation of clouds and precipitation in the tropical atmosphere is of primary importance to their impacts on radiative forcing and the hydrological cycle. Measurements of aerosol number size distribution, hygroscopicity in both sub- and supersaturated regimes and composition were taken between March and July 2008 in the tropical rainforest in Borneo, Malaysia, marking the first study of this type in an Asian tropical rainforest. Hygroscopic growth factors (GF) at 90 % relative humidity (RH) for the dry diameter range D0 = 32–258 nm, supersaturated water uptake behaviour for the dry diameter range D0 = 45–300 nm and aerosol chemical composition were simultaneously measured using a Hygroscopicity Tandem Differential Mobility Analyser (HTDMA), a Droplet Measurement Technologies Cloud Condensation Nuclei counter (CCNc) and an Aerodyne Aerosol Mass Spectrometer (AMS) respectively. The hygroscopicity parameter κ was derived from both CCNc and HTDMA measurements, with the resulting values of κ ranging from 0.05–0.37, and 0.17–0.37, respectively. Although the total range of κ values is in good agreement, there are inconsistencies between CCNc and HTDMA derived κ values at different dry diameters. Results from a study with similar methodology performed in the Amazon rainforest report values for κ within a similar range to those reported in this work, indicating that the aerosol as measured from both sites shows similar hygroscopic properties. However, the derived number of cloud condensation nuclei (NCCN) were much higher in the present experiment than the Amazon, resulting in part from the increased total particle number concentrations observed in the Bornean rainforest. This contrast between the two environments may be of substantial importance in describing the impacts of particles in the tropical atmosphere.

Host specificity and niche partitioning in flea-small mammal networks in Bornean rainforests

The diversity of ectoparasites in Southeast Asia and flea-host associations remain largely understudied. We explore specialization and interaction patterns of fleas infesting non-volant small mammals in Bornean rainforests, using material from a field survey carried out in two montane localities in northwestern Borneo (Sabah, Malaysia) and from a literature database of all available interactions in both lowland and montane forests. A total of 234 flea individuals collected during our field survey resulted in an interaction network of eight flea species on seven live-captured small mammal species. The interaction network from all compiled studies currently includes 15 flea species and 16 small mammal species. Host specificity and niche partitioning of fleas infesting diurnal treeshrews and squirrels were low, with little difference in specialization among taxa, but host specificity in lowland forests was found to be higher than in montane forests. By contrast, Sigmactenus alticola (Siphonaptera: Leptopsyllidae) exhibited low host specificity by infesting various montane and lowland nocturnal rats. However, this species exhibited low niche partitioning as it was the only commonly recorded flea from rats on Borneo. Overall complementary specialization was of intermediate intensity for both networks and differed significantly from random association; this has important implications for specific interactions that are also relevant to the potential spread of vector-borne diseases.

Partitioning the impact of abiotic factors and spatial patterns on species richness and community structure of ground ant assemblages in four Bornean rainforests

Contrasting theories have been proposed to explain the structure of ecological communities. Here, we studied the impact of environmental factors and spatial patterns on ground-foraging ant communities in four different forest types of Gunung Mulu National Park in Sarawak, Borneo, Malaysia. Forest types differed in their environmental parameters and were inhabited by distinct ant communities, with various indicator species characteristic for single forest types. Three environmental parameters, soil volume, number of trees and amount of leaf litter, had the most influence on ant communities. Spatial patterns were correlated with environmental parameters and also influenced ant communities. Environmental parameters influenced community composition only moderately (r 2 = 0.14), but had a high impact on species richness (r 2 =0.44). Spatial patterns explained only a small fraction of the total variance in species patterns, while much of the residual space in the ordination space of ant community patterns remained unexplained. We conclude that environmental parameters shape the number of niches within a tropical soil habitat, but identities of species that occupy those niches are accounted for by other factors like competition, traits and neutral processes that may further reduce unexplained variance in species ordination.

Variation in leaf stomatal traits of 28 tree species in relation to gas exchange along an edaphic gradient in a Bornean rain forest

Quantifying variation in functional traits associated with shifts in the species composition of plant communities along resource gradients helps identify environmental attributes important for community assembly. Stomates regulate the balance between carbon assimilation and water status in plants. If environmental attributes affecting photosynthetic water-use efficiency govern species distribution along an edaphic gradient, then adaptive variation in stomatal traits of plant species specializing on different soils should reflect belowground resource availability. • We tested this hypothesis by quantifying stomatal trait variation in understory saplings of 28 Bornean tree species in relation to gas exchange and water-use efficiency (WUE). • Comparisons between congeneric specialists of the more fertile, moister clay and the less fertile, well-drained sandy loam revealed little evidence of similar shifts in stomatal traits across genera, nor was stomatal pore index correlated with g(max), A(max), or WUE (A(max)/g(max) or Δ(13)C), suggesting that stomates may be overbuilt in these shaded juveniles. A(max) was higher on sandy loam, likely due to higher understory irradiance there, but there were no other significant differences in gas exchange or WUE. • Despite substantial diversity in stomatal anatomy, there were few strong relationships between stomatal, photosynthetic, and WUE traits in relation to soil resources. Routine differences in water availability therefore may not exert a dominant control on the distributions of these Bornean tree species. Furthermore, the clades represented by these 12 genera may possess alternative functional designs enabling photosynthetic WUE that is sufficient to these humid, understory environments, due to whole plant-functional integration of stomatal traits with other, unmeasured traits influencing gas exchange.

Is nest temperature an important factor for niche partitioning by leaf-litter ants (Hymenoptera: Formicidae) in Bornean rain forests?

Abstract:We tested the hypothesis that species of a diverse leaf-litter ant community are separated by the temperature preferences of their broods along a thermal gradient. Therefore, temperature preferences of brood-tending workers from 41 ant species co-occurring in four types (alluvial, limestone, kerangas and dipterocarp forest) of primary rain forest in Sarawak, Malaysia were measured in an experimental set-up. Preferred temperatures of species ranged from 16.0 °C to 31.7 °C, with the median at 25.8 °C. The ten commonest species (n ≥ 4) showed significantly different temperature preferences. In particular, species of the genus Pheidole differed clearly in their preferences over a broad range of temperatures. Temperature preferences varied significantly among ant assemblages from different forest types and nest sites. Experimentally obtained temperature preferences of species correlated significantly with vegetation density in the plots inhabited by the respective species, but not with plot canopy cover. When we tested the temperature preferences of all ant species with null models for niche overlap, we found a significant niche separation only among the tested species from the kerangas. Our results suggest that nest temperature is an important ecological factor for leaf-litter ants in rain forests on Borneo, but other factors may override its influence during community assembly.

Seasonality in light‐attracted chrysomelid populations in a Bornean rainforest

Abstract. 1. Seasonal or annual population fluctuations have been reported for various tropical insect species, exhibiting one or more peaks in abundance at certain times of the year. Such fluctuations have mostly been observed in areas that experience annual wet and dry seasons, and not in areas where climatic fluctuations are unpredictable on an annual basis.2. This study attempted to evaluate the extent of seasonality in population fluctuations of a light‐trapped chrysomelid assemblage consisting of 25 Garelucinae and one Eumolpinae in a Bornean rainforest that is characterised by an aseasonal climate.3. This study also attempted to test the effects of short‐term rainfall changes and leaf‐flushing phenology on chrysomelid population fluctuations.4. The majority of the chrysomelid species showed one or more abundance peaks that were unrelated to season.5. The population fluctuations did not correspond to short‐term fluctuations in rainfall or leaf‐flushing phenology, although these environmental factors somewhat correlated with each other and fluctuated irregularly.6. These results suggest that populations of most chrysomelids fluctuate aseasonally and that short‐term fluctuations in rainfall and leaf‐flushing phenology hardly affect population fluctuations in Bornean rainforests where seasonal climate patterns are weak.

Evolutionary history and distance dependence control survival of dipterocarp seedlings

One important hypothesis to explain tree-species coexistence in tropical forests suggests that increased attack by natural enemies near conspecific trees gives locally rare species a competitive advantage. Host ranges of natural enemies generally encompass several closely related plant taxa suggesting that seedlings should also do poorly around adults of closely related species. We investigated the effects of adult Parashorea malaanonan on seedling survival in a Bornean rain forest. Survival of P. malaanonan seedlings was highest at intermediate distances from parent trees while heterospecific seedlings were unaffected by distance. Leaf herbivores did not drive this relationship. Survival of seedlings was lowest for P. malaanonan, and increased with phylogenetic dissimilarity from this species, suggesting that survival of close relatives of common species is reduced. This study suggests that distance dependence contributes to species coexistence and highlights the need for further investigation into the role of shared plant enemies in community dynamics.

Population fluctuations of light-attracted chrysomelid beetles in relation to supra-annual environmental changes in a Bornean rainforest

In Southeast Asian tropical rainforests, two events, severe droughts associated with the El Niño-Southern Oscillation and general flowering, a type of community-wide mass flowering, occur at irregular, supra-annual intervals. The relationship between these two supra-annual events and patterns of insect population fluctuations has yet to be clearly elucidated. Leaf beetles (Chrysomelidae) are major herbivores and flower-visitors of canopy trees, affecting their growth and reproduction and, in turn, affected by tree phenology; but their population fluctuations in the Southeast Asian tropics have not been extensively investigated. We examined population fluctuation patterns of the 34 most dominant chrysomelid species in relation to the two supra-annual events by conducting monthly light-trapping over seven years in a lowland dipterocarp forest in Borneo. Our results showed large community variation in population fluctuation patterns and a supra-annual (between-year) variation in abundance for most of the dominant chrysomelids that was significantly larger than the annual (within-year) variation. Specifically, in response to a severe drought in 1998, chrysomelid species exhibited different population responses. These results show that population fluctuations of individual species, rather than the entire assemblage, must be analyzed to determine the effects of changes in environmental conditions on the structure of insect assemblages in the tropics, especially in regions where supra-annual environmental changes are relatively more important than seasonal changes.

Tree diversity, composition, forest structure and aboveground biomass dynamics after single and repeated fire in a Bornean rain forest

Forest fires remain a devastating phenomenon in the tropics that not only affect forest structure and biodiversity, but also contribute significantly to atmospheric CO2. Fire used to be extremely rare in tropical forests, leaving ample time for forests to regenerate to pre-fire conditions. In recent decades, however, tropical forest fires occur more frequently and at larger spatial scales than they used to. We studied forest structure, tree species diversity, tree species composition, and aboveground biomass during the first 7 years since fire in unburned, once burned and twice burned forest of eastern Borneo to determine the rate of recovery of these forests. We paid special attention to changes in the tree species composition during burned forest regeneration because we expect the long-term recovery of aboveground biomass and ecosystem functions in burned forests to largely depend on the successful regeneration of the pre-fire, heavy-wood, species composition. We found that forest structure (canopy openness, leaf area index, herb cover, and stem density) is strongly affected by fire but shows quick recovery. However, species composition shows no or limited recovery and aboveground biomass, which is greatly reduced by fire, continues to be low or decline up to 7 years after fire. Consequently, large amounts of the C released to the atmosphere by fire will not be recaptured by the burned forest ecosystem in the near future. We also observed that repeated fire, with an inter-fire interval of 15 years, does not necessarily lead to a huge deterioration in the regeneration potential of tropical forest. We conclude that burned forests are valuable and should be conserved and that long-term monitoring programs in secondary forests are necessary to determine their recovery rates, especially in relation to aboveground biomass accumulation.

Interspecific demographic trade‐offs and soil‐related habitat associations of tree species along resource gradients

1 Interspecific relationships between fundamental demographic rates, often called demographic trade-offs, emerge from constraints within individuals related to morphology, physiology and resource allocation. Plant species that grow fast in high light usually have high mortality in shade, and this well-established relationship in part defines a species’ successional niche. More generally, this relationship represents a trade-off between a species’ ability to grow quickly to exploit abundant resources vs. avoiding mortality when resources are less plentiful, but few studies have described this demographic trade-off with respect to environmental factors other than light. 2 Using demographic data from 960 tree species in Bornean rain forest, we examined the evidence for an interspecific demographic trade-off between fast growth and low mortality and its variation among habitats defined by variation in soil fertility and moisture. Such a trade-off could contribute to sorting of tree species among habitats and partly explain the striking patterns of species’ edaphic associations in this and other forests. 3 We found strong evidence for this demographic trade-off, both within the same habitat and when growth on edaphically rich habitats was compared with mortality on a habitat with lower below-ground resource availability. 4 The slope of the growth-mortality relationship varied among habitats, being steepest on the habitat lowest in below-ground resources. For species with the fastest potential growth rates, mortality was higher on this habitat than at comparable growth rates on the three more edaphically rich habitats, providing a possible mechanism by which fast-growing species may be eliminated from the poorest habitat. Adaptations for fast growth may entail a greater mortality risk, if inherently fast-growing species fail to maintain a positive C-balance when below-ground resources are scarce. 5 Conversely, for species with the slowest potential growth rates, the highest species’ mortality rates occurred on the habitats with greatest below-ground resource availability, implying that slow-growing species may have a competitive disadvantage in resource-rich environments. 6 Synthesis. Differences among habitats in the steepness of this trade-off may sort species into different habitats along this edaphic gradient, whereas on the same soil, this demographic trade-off could facilitate coexistence of at least some species in this forest. Thus, by generating emergent demographic trade-offs that vary along resource gradients, plant life-history strategies can influence species diversity and distribution.

Deadly dances in the Bornean rainforest: hunting knowledge of the Penan Benalui – By Rajindra K. Puri

Deadly dances in the Bornean rainforest: hunting knowledge of the Penan Benalui – By Rajindra K. Puri

The Tropical Ant Mosaic in a Primary Bornean Rain Forest

ABSTRACTIn primary lowland rain forest in Brunei Darussalam, we studied arboreal ant communities to evaluate whether densities and spacing of spatially territorial taxa along 2.9 km of well‐studied trails are consistent with existence of a continuous mosaic of dominant ants. A median intercolony distance of 24.5 m, about twice or less distances over which colonies of most included species regularly ranged, suggested a relatively continuous mosaic. Despite relying on nesting sites in preformed plant cavities, carpenter ants contributed > 70 percent of mapped colonies. Most belonged to the Camponotus (Colobopsis) cylindricus (COCY) complex, including SE Asia's ‘exploding’ ants. Their lack of aggression against certain Polyrhachis species was associated with interspecific territory sharing by members of the two groups, and with a dominance‐discovery trade‐off. Experimental approaches yielded evidence for two putative contributors to positive association. Larger‐bodied Polyrhachis parasitize food‐finding abilities of smaller, more populous Camponotus workers, and the two taxa cooperate in territorial defense. Highly territorial and predatory weaver ants (Oecophylla smaragdina) were an important component of the ant mosaic in primary forest, second only to codominant COCY and Polyrhachis taxa. Members of the genus Crematogaster were significantly associated with Oecophylla in baiting censuses and regularly monopolized near‐nest baits to the exclusion of weaver ants. Litter ant abundances differed between territories of Oecophylla and less predatory COCY species, but direction of difference was inconsistent over time. The densely packed mosaic of spatially territorial, and differentially predatory, taxa in Bornean rain forest likely contributes to spatial variation in ant effects on plant and arthropod communities.

Phylogenetic and ecological correlates with male adult life span of rainforest butterflies

Adult life spans are an important life history variable in butterflies, but have rarely been investigated in cross-species comparisons. Using 377 captive specimens from a Bornean rainforest assemblage (wild catches with low wing wear, belonging to 102 species) under standardized feeding conditions, substantial differences in the average adult life spans of species were observed, ranging from few days to almost three weeks. Analyses were carried out on the 30 most common species (247 specimens, only males). They revealed that related taxa had similar life spans, with nymphalids and some lycaenid groups being generally longer-lived than other taxa. Two traits of adult feeding behaviour are strong predictors of longevity in multivariate, phylogeny-controlled analyses: Fruit-feeding (versus nectar feeding) is associated with longer life spans, whereas the occurrence of mud-puddling behaviour is associated with short adult life. Larval feeding, male territoriality and a number of morphological measures showed no independent relationships with life spans. Furthermore, there was no evidence that long-lived species have larger geographic distributions (i.e., are better dispersers). Explanatory hypotheses are put forward, which may be a starting point for further investigations.