Comparison of rainforest butterfly assemblages across three biogeographical regions using standardized protocols

Insects, like most other organisms, are more diverse in tropical than in temperate regions, but standardized comparisons of diversity among tropical regions are rare. Disentangling the effects of ecological, evolutionary, and biogeographic factors on community diversity requires standardized protocols and long-term studies. We compared the abundance and diversity of butterflies using standardised ‘Pollard walk’ transect counts in the understory of closed-canopy lowland rainforests in Panama (Barro Colorado Island, BCI), Thailand (Khao Chong, KHC) and Papua New Guinea (Wanang, WAN). We observed 1792, 1797 and 3331 butterflies representing 128, 131 and 134 species during 230, 231 and 120 transects at BCI, KHC and WAN, respectively. When corrected for length and duration of transects, butterfly abundance and species richness were highest at WAN and KHC, respectively. Although high butterfly abundance at WAN did not appear to result from methodological artefacts, the biological meaning of this observation remains obscure. The WAN site appeared as floristically diverse as KHC, but supported lower butterfly diversity. This emphasizes that factors other than plant diversity, such as biogeographic history, may be crucial for explaining butterfly diversity. The KHC butterfly fauna may be unusually species rich because the site is at a biogeographic crossroads between the Indochinese and Sundaland regions. In contrast, WAN is firmly within the Australian biogeographic region and relatively low species numbers may result from island biogeographic processes. The common species at each of the three sites shared several traits: fruit and nectar feeders were equally represented, more than half of common species fed on either epiphytes or lianas as larvae, and their range in wing sizes was similar. These observations suggest that Pollard walks in different tropical rainforests target similar assemblages of common species, and, hence, represent a useful tool for long-term monitoring of rainforest butterfly assemblages.Organismic and Evolutionary Biolog

Data from: Inter-annual monitoring improves diversity estimation of tropical butterfly assemblages

Monitoring programs for diverse tropical butterfly assemblages are scarce and temporal diversity patterns in these assemblages are poorly understood. We adopted an additive partitioning approach to determine how temporal butterfly species richness was structured at the levels of days, months, and years in five tropical/subtropical sites across three continents covering up to nine years of monitoring. We found that observed butterfly richness was not uniformly distributed across temporal extents. Butterfly species composition differed across months and years, potentially accounting for the fact that temporal butterfly species richness contributed a high proportion to total species richness. We further examined how species richness of common and uncommon species (> and <0.5 percent of total abundance, respectively) were structured across temporal extents. The results showed that the common species relative contribution to total species richness was higher at lower-temporal levels, whereas uncommon species contributed more at higher-temporal resolutions. This suggests that long-term sampling will be more effective in capturing patterns of rare species and the total species pool while lower-temporal level sampling (e.g. daily or weekly) may be more useful in examining common species demographic patterns. We therefore encourage careful consideration of temporal replication at different extents in developing butterfly monitoring schemes. Long-term monitoring is essential for improvement in the resolution of species estimation and diversity patterns for tropical ecosystems

Cross-continental comparisons of butterfly assemblages in tropical rainforests: implications for biological monitoring

1. Standardised transect counts of butterflies in old-growth rainforests in different biogeographical regions are lacking. Such data are needed to mitigate the influence of methodological and environmental factors within and between sites and, ultimately, to discriminate between long-term trends and short-term stochastic changes in abundance and community composition. 2. We compared butterfly assemblages using standardised Pollard Walks in the understory of closed-canopy lowland tropical rainforests across three biogeographical regions: Barro Colorado Island (BCI), Panama; Khao Chong (KHC), Thailand; and Wanang (WAN), Papua New Guinea. 3. The length and duration of transects, their spatial autocorrelation, and number of surveys per year represented important methodological factors that strongly influenced estimates of butterfly abundance. Of these, the effect of spatial autocorrelation was most difficult to mitigate across study sites. 4. Butterfly abundance and faunal composition were best explained by air temperature, elevation, rainfall, wind velocity, and human disturbance at BCI and KHC. In the absence of weather data at WAN, duration of transects and number of forest gaps accounted for most of the explained variance, which was rather low in all cases (<33%). 5. Adequate monitoring of the abundance of common butterflies was achieved at the 50 ha BCI plot, with three observers walking each of 10 transects of 500 m for 30 min each, during each of four surveys per year. These datamay be standardised further after removing outliers of temperature and rainfall. Practical procedures are suggested to implement globalmonitoring of rainforest butterflies with Pollard Walks.Organismic and Evolutionary Biolog

Data from: The insect-focused classification of fruit syndromes in tropical rainforests: an inter-continental comparison

We propose a new classification of rainforest plants into eight fruit syndromes, based on fruit morphology and other traits relevant to fruit-feeding insects. This classification is compared with other systems based on plant morphology or traits relevant to vertebrate fruit dispersers. Our syndromes are based on fruits sampled from 1,192 plant species at three Forest Global Earth Observatory plots: Barro Colorado Island (Panama), Khao Chong (Thailand) and Wanang (Papua New Guinea). The three plots differed widely in fruit syndrome composition. Plant species with fleshy, indehiscent fruits containing multiple seeds were important at all three sites. However, in Panama a high proportion of species had dry fruits, while in New Guinea and Thailand, species with fleshy drupes and thin mesocarps were dominant. Species with dry, winged seeds that do not develop as capsules were important in Thailand, reflecting the local importance of Dipterocarpaceae. These differences can also determine differences among frugivorous insect communities. Fruit syndromes and colours were phylogenetically flexible traits at the scale studied, as only three of the eight seed syndromes, and one of the 10 colours, showed significant phylogenetic clustering at either genus or family levels. Plant phylogeny was, however, the most important factor explaining differences in overall fruit syndrome composition among individual plant families or genera across the three study sites