Espinosa, C. I. | bioRxiv Science

bioRxiv2026

Competition and niche partitioning of floral resources between two native stingless bees (Melipona mimetica and Scaptotrigona sp., Apidae: Meliponini) in a seasonally dry tropical forest of Ecuador

Stingless bees are key pollinators in tropical ecosystems, yet their ecological dynamics remain poorly understood in highly seasonal environments such as the seasonally dry tropical forests of Ecuador. These ecosystems experience pronounced climatic seasonality, with sharp transitions between dry and wet periods that strongly affect floral resource availability. Understanding interspecific competition and niche partitioning in such systems is critical, particularly given the global decline of pollinators. We investigated resource use and niche dynamics in two native stingless bees, Melipona mimetica and Scaptotrigona sp., by quantifying pollen, nectar, and resin collection across seasons. Log-linear models were used to test the effects of species, season, and their interaction on resource use, while non-metric multidimensional scaling (NMDS) assessed niche overlap. Contrary to the expectation that niche overlap increases under resource scarcity, we found greater overlap during the wet season, when resources are more abundant. This suggests that both species converge on high-quality floral resources during peak availability, reflecting an adaptive response to strong environmental seasonality. Pollen use remained stable across seasons, consistent with generalist foraging behavior. In contrast, nectar collection increased significantly during the wet season, while resin exhibited a shared seasonal peak, likely associated with synchronized nest construction or maintenance. These findings reveal context-dependent competition dynamics and highlight the role of environmental seasonality in shaping pollinator interactions. Our study provides new insights into the ecology of threatened stingless bees and contributes to their conservation in tropical dry forest ecosystems.

ecology↗

bioRxiv2023

Woody plant taxonomic, functional, and phylogenetic diversity decrease along elevational gradients in Andean tropical montane forests: environmental filtering and arrival of temperate taxa

AimMountains are paramount for exploring biodiversity patterns and their causes due to the rich mosaic of topographies and climates encompassed over short geographical distances. Biodiversity changes along elevational gradients have traditionally been explored in terms of taxonomic diversity, but other aspects must be considered. For first time, we simultaneously assessed elevational trends in the taxonomic, functional, and phylogenetic diversity of woody plants in Andean tropical montane forests (TMFs) and explored their underlying ecological and evolutionary causing processes. LocationTropical Andes Time period2011/2012 and 2017/2019 Tropical Andes Major TaxaWoody plants MethodsWe investigated taxonomic, functional, and phylogenetic diversity along four transects (traversing ca. 2,200 m altitudinal gradients) encompassing 114 0.1 ha plots across a broad latitudinal range (ca. 10{degrees}). We used Hill numbers to quantify differences in the abundance-based diversity of 37,869 woody plant individuals with DBH [≥] 2.5 cm. ResultsTaxonomic, functional, and phylogenetic diversity decreased as elevation increased. The decrease was less pronounced for Hill numbers of higher orders. The only exception was a slight increase in phylogenetic diversity when more weight was given to dominant species. These results were consistent between transects. Main conclusionsThe decrease in taxonomic and functional diversity with elevation might be due to an environmental filtering process where the increasingly harsher conditions towards highlands exclude species and functional strategies. Besides, the differences in the steepness of the decrease between Hill orders suggest that rare species contribute disproportionately to functional diversity. The shifting elevational trend in the phylogenetic diversity between Hill orders indicates a greater than previously considered influence in central tropical Andean highlands of species originated in lowlands with strong niche conservatism relative to distantly related temperate lineages. This could be explained by a decreasing presence and abundance of extratropical taxa towards the central Andes relative to northern or southern Andes. BIOSKETCHGuillermo Banares-de-Dios is a plant ecologist with interests in community assembly, biodiversity patterns, and global change. He completed his PhD in 2020 and belongs to "Grupo de Ecologia Tropical", an international network of researchers from different institutions with broad interests in tropical biology (http://www.grupoecologiatropical.com/?lang=en). Currently he works as Project Manager implementing the European Pollinator Monitoring Scheme in Spain.

ecology↗

bioRxiv2017

More than Drylands but Less of Dry Forests

The recent Global Drylands Assessment of forests is based on both an incomplete delimitation of dry forests distribution and on an old and incorrect delimitation of drylands. Its sampling design includes a large proportion of plots located in humid ecosystems and ignores critical areas for the conservation of dry forests. Therefore its results and conclusions are unreliable.

ecology↗