The transition zone between the Nearctic and Neotropical biogeographic regions is one of the most species-rich areas of North America, known as the Mexican Transition Zone. We sampled mobile insects along a 2000 m elevational gradient for 13 months using flight interception traps (Malaise) to evaluate their diversity, community structure and environmental factors linked to their distribution. We identified 3091 Molecular Operational Taxonomical Units (560 ± 199 SD per trap), out of which 513 were identified to genus and 197 to species. Our results show high turnover at both species and genus levels across the elevational gradient. Elevational diversity patterns varied across taxa: Coleoptera and Lepidoptera showed their highest diversity at mid-elevations, while Diptera and Hymenoptera had increased diversity with elevation. Temperature and vegetation composition best explained the spatial fluctuations of insect diversity. Our work represents the most comprehensive survey of insect communities in the region to date. By combining a long-term survey with high-throughput metabarcoding, this study provides an overview of regional diversity and establishes a foundation for detailed follow-up studies.

• MeSH
• Biodiversity * MeSH
• Insecta * genetics   classification   MeSH
• Altitude * MeSH
• DNA Barcoding, Taxonomic * methods   MeSH
• Tropical Climate MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Mexico MeSH

Gradients in species diversity across elevations and latitudes have fascinated biologists for decades. While these gradients have been well documented for macroorganisms, there is limited consensus about their universality, shape and drivers for microorganisms, such as fungi, despite the importance of fungal diversity for ecosystem functions and services. We conducted a comprehensive survey of fungal species richness in forests across 17 elevational transects along a latitudinal gradient covering the continental scale of Europe. Diversity patterns along elevational and latitudinal gradients differed among fungal ecological guilds. Diversity of saprotrophs declined with elevation while ectomycorrhizal (ECM) fungal diversity peaked in mid-elevations. Moreover, the diversity of root endophytic fungi increased with latitude but did not change with elevation. Bayesian species distribution modeling suggests that fungal diversity is structured by deterministic rather than stochastic drivers. Importantly, ECM fungal diversity pattern persists even after accounting for the effects of environmental conditions. These results suggest that environmental conditions differentially shape the diversity of fungal guilds along elevational and latitudinal gradients, but this goes beyond soil and climatic factors in the case of ECM fungi. This study paves the way toward a better understanding of fungal diversity gradients across elevations and latitudes, with possible implications for macroecological theory, conservation and management.

• Keywords
• altitudinal and latitudinal gradients, biogeography, climate, ectomycorrhizal fungi, fungal diversity, join species distribution models, root endophytic fungi, saprotrophic fungi,
• MeSH
• Bayes Theorem MeSH
• Biodiversity * MeSH
• Fungi * physiology   MeSH
• Mycorrhizae physiology   MeSH
• Altitude * MeSH
• Geography MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Europe MeSH

We use community phylogenetics to elucidate the community assembly mechanisms for Geometridae moths (Lepidoptera) collected along a complete rainforest elevational gradient (200-3700 m a.s.l) on Mount Wilhelm in Papua New Guinea. A constrained phylogeny based on COI barcodes for 604 species was used to analyse 1390 species x elevation occurrences at eight elevational sites separated by 500 m elevation increments. We obtained Nearest Relatedness Index (NRI), Nearest Taxon Index (NTI) and Standardised Effect Size of Faith's Phylogenetic Diversity (SES.PD) and regressed these on temperature, plant species richness and predator abundance as key abiotic and biotic predictors. We also quantified beta diversity in the moth communities between elevations using the Phylogenetic Sorensen index. Overall, geometrid communities exhibited phylogenetic clustering, suggesting environmental filters, particularly at higher elevations at and above 2200 m a.s.l and no evidence of overdispersion. NRI, NTI and SES.PD showed no consistent trends with elevation or the studied biotic and abiotic variables. Change in community structure was driven by turnover of phylogenetic beta-diversity, except for the highest 2700-3200 m elevations, which were characterised by nested subsets of lower elevation communities. Overall, the elevational signal of geometrid phylogeny was weak-moderate. Additional insect community phylogeny studies are needed to understand this pattern.

• MeSH
• Biodiversity * MeSH
• Rainforest * MeSH
• Phylogeny * MeSH
• Moths * genetics   physiology   classification   MeSH
• Altitude * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Papua New Guinea MeSH

Both the abiotic environment and the composition of animal and plant communities change with elevation. For mutualistic species, these changes are expected to result in altered partner availability, and shifts in context-dependent benefits for partners. To test these predictions, we assessed the network structure of terrestrial ant-plant mutualists and how the benefits to plants of ant inhabitation changed with elevation in tropical forest in Papua New Guinea. At higher elevations, ant-plants were rarer, species richness of both ants and plants decreased, and the average ant or plant species interacted with fewer partners. However, networks became increasingly connected and less specialized, more than could be accounted for by reductions in ant-plant abundance. On the most common ant-plant, ants recruited less and spent less time attacking a surrogate herbivore at higher elevations, and herbivory damage increased. These changes were driven by turnover of ant species rather than by within-species shifts in protective behaviour. We speculate that reduced partner availability at higher elevations results in less specialized networks, while lower temperatures mean that even for ant-inhabited plants, benefits are reduced. Under increased abiotic stress, mutualistic networks can break down, owing to a combination of lower population sizes, and a reduction in context-dependent mutualistic benefits.

• Keywords
• altitudinal gradients, biotic defence, global change, herbivory, myrmecophyte, network specialization,
• MeSH
• Herbivory MeSH
• Ants * MeSH
• Forests MeSH
• Altitude MeSH
• Plants * MeSH
• Symbiosis * MeSH
• Tropical Climate MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Papua New Guinea MeSH