Biology subjects

Kobe, I. N.

Publications and source records attributed to Kobe, I. N..

6 recordsLinked to original sources

bioRxiv2026

Plant-pollinator interactions along an elevational gradient in Central European forest understorey

Elevational gradients provide a framework for understanding how environmental filtering reorganises communities and interactions, but plant-pollinator interactions along temperate forest elevational gradients remain overlooked. We studied early-spring understorey communities at four forest sites spanning the foothills towards the timberline (450-1,000 m a.s.l.) in the Krkono[s]e Mountains, Czechia. Across six transects per elevation, we quantified flowering plant species richness, floral resources and traits, and video-recorded flowers, yielding 4,003 pollinator visits. We analysed elevational patterns in species richness, community composition, floral traits, and quantitative network characteristics. Visitation frequency and flowering plant and pollinator species richness peaked at intermediate elevations. The contribution of dipteran relative to hymenopteran pollinators increased towards higher elevations, principally because of non-hoverfly flies, whereas individual bee groups showed no uniform response. Floral resources and traits showed no uniform elevational responses, although total nectar sugar availability peaked at the highest site because of the dominant Vaccinium myrtillus. Most notably, both network-level specialisation and mean species-level specialisation were generally greater at the two higher elevations, whereas nestedness was lower and other network characteristics showed no consistent patterns. These findings suggest that shifts in pollinator composition and dominant floral resources potentially shaped interactions along the gradient. The increasing specialisation with elevation contrasts with the generalisation often expected under reduced partner availability and indicates that forest networks may follow elevational patterns not predicted from open habitats. Despite limited site-level replication, this study provides, to our knowledge, the first community-wide characterisation of plant-pollinator interactions along a temperate forest elevational gradient and identifies patterns requiring evaluation across replicated gradients.

ecology↗

bioRxiv2026

Elevational patterns in plant mating systems and pollen limitation in Afrotropical montane grasslands

O_LIPlant mating systems and pollen limitation often vary along elevational gradients, yet empirical evidence remains mixed and rarely comes from multi-species experimental studies in tropical mountain ecosystems. C_LIO_LIWe tested how elevation affects natural seed set, pollen limitation, and selfing capacity, and whether these patterns are associated with variation in flower visitation, in Afromontane grasslands on Mount Cameroon. We conducted a hand-pollination experiment on seven zoogamous plant species at four elevations above the timberline (2,300-3,800 m), applying autonomous selfing, geitonogamous selfing, outcrossing, and open-pollination treatments to 1,776 flowers and quantifying seed set. In parallel, we quantified pollinator visitation on unmanipulated plants to estimate visitation frequency, morphospecies richness, and functional-group richness. C_LIO_LINatural reproductive success of the studied plants exhibited a pronounced mid-elevation peak and declined sharply towards the summit, where pollen limitation increased strongly. At the highest elevation, some species produced few or no seeds even under outcross-pollination, indicating physiological reproductive constraints. C_LIO_LIIndices of autonomous selfing and geitonogamy varied among species, with no consistent elevational patterns. Despite detected partial self-compatibility, summit populations did not exhibit expected shifts towards selfing, suggesting limited reproductive assurance under high-elevation conditions. C_LIO_LIPollinator visitation frequency and diversity declined at the highest elevation. Natural seed set was positively associated with visitation frequency and mildly negatively associated with morphospecies richness, whereas pollen limitation and selfing indices showed no clear relationships with visitation metrics, consistent with the influence of additional physiological and developmental constraints on reproduction. C_LIO_LISynthesis. Our study shows that in isolated Afrotropical montane grasslands, plant reproductive success at high elevations is jointly constrained by declining pollination service and abiotic limitations, which is not compensated by increased selfing. This suggests that successful plant reproduction near upper vegetation limits depends on both sufficient pollination service and favourable physiological conditions. Under ongoing climate change, upslope range shifts of plants may therefore not guarantee reproductive success if plant and pollinator responses to warming are asynchronous or if a part of extreme high-elevation conditions remain limiting. These findings advance understanding of how biotic interactions and abiotic constraints together shape plant reproduction along tropical elevational gradients. C_LI

plant biology↗

bioRxiv2025

Butterfly and moth habitat specialisation changes along an elevational gradient of tropical forests on Mount Cameroon

Niche breadth is a key ecological trait influencing species distribution, persistence, vulnerability to environmental change, and interspecific interactions. While the elevational niche-breadth hypothesis predicts broader ecological niches at higher elevations due to increased environmental stress and heterogeneity, empirical tests have mostly focused on food specialisation, with habitat specialisation remaining largely overlooked. Here, we provide the first direct test of this hypothesis using habitat characteristics, analysing fruit-feeding butterflies and moths along a complete tropical forest gradient on Mount Cameroon. We quantified habitat-related niche breadth using the Outlying Mean Index across 96 forest plots spanning 350-2200 m a.s.l., employing two complementary metrics: absolute niche breadth (ANB) based on the total range of habitat conditions occupied across the gradient, and within-elevation niche breadth (WENB) reflecting the proportion of local habitat heterogeneity utilized at each elevation. Forest structural heterogeneity increased steeply with elevation. In response, butterfly communities showed a substantial upslope broadening of ANB, particularly in Charaxinae and Satyrinae. Moth families exhibited similar but weaker patterns. In contrast, WENB showed no consistent elevational patterns and was more variable among lepidopteran groups. These results support the elevational niche-breadth hypothesis for habitat specialisation in tropical butterflies, likely reflecting increased habitat opportunity space and reduced competition at higher elevations. However, the decoupling of ANB and WENB highlights that broader availability of environmental conditions does not necessarily translate into more generalised local habitat use, suggesting constraints from behavioural preferences, resource distributions, or biotic interactions. By disentangling overall and local habitat niche breadths, our study reveals unrecognised complexity in elevational specialisation patterns and provides new insights into how tropical insect respond to environmental gradients.

ecology↗

bioRxiv2021

Role and patterns of butterflies and hawkmoths in plant-pollinator networks at different elevations and seasons in tropical rainforests of Mount Cameroon

O_LIButterflies and moths are well-visible flower visitors. Nevertheless, almost no quantification of their role in plant-pollinator interactions exists at a community level, especially from tropical rainforests. Moreover, we have virtually no knowledge on environmental and other factors affecting lepidopteran flower visits. C_LIO_LIWe focused on the role of butterflies and hawkmoths as flower visitors in tropical rainforests of Mount Cameroon, especially on its elevational and seasonal changes. We also analysed their preferences to selected floral traits, with a specific focus on pollination syndromes. C_LIO_LIWe video-recorded flower visitors of 1,115 specimens of 212 plant species (>26,000 recording hrs) along the complete elevational gradient of rainforests in two main seasons, and compared frequencies of flower-visiting lepidopterans to other visitors. We compared characteristics of plant-lepidopteran networks among elevations and seasons, and analysed patterns of selected lepidopteran traits. Finally, we analysed inter-family differences in their floral preferences. C_LIO_LIAltogether, we recorded 734 flower visits by 80 butterflies and 27 hawkmoth species, representing only ~4% of all 18,439 flower visits. Although lepidopterans visited only a third species, they appeared key visitors of several plants. The most flower visits by lepidopterans were recorded in mid-elevations and dry season, mirroring the general patterns of lepidopteran diversity. The networks showed no apparent elevational or seasonal patterns, probably because of the surprisingly high specialisation of interactions in all networks. Significant non-linear changes of proboscis and forewing lengths were found along elevation, and long-proboscid hesperiid butterflies visited flowers with longer tubes or spurs. Substantial differences in floral preferences were found between sphingids, and papilionid, nymphalid and lycaenid butterflies, revealing importance of nectar production, floral size and shape for sphingids, and floral colour for butterflies. C_LIO_LIButterflies and hawkmoths were confirmed as relatively minor visitors of tropical forest flowers, although they seemed crucial for pollination of some plant species. Moreover, the revealed floral preferences and trait-matchings confirmed a potential of some lepidopteran families to drive floral evolution in tropical ecosystems. C_LI

ecology↗

bioRxiv2020

Spatiotemporal shifts in the role of floral traits in shaping tropical plant-pollinator interactions

The pollination syndrome hypothesis predicts that plants pollinated by the same pollinator group bear convergent combinations of specific floral traits. Nevertheless, some studies have shown relatively low predictive power for these floral trait combinations. This discrepancy may be caused by changes in the importance of specific floral traits for shaping interactions under different environmental conditions and for different pollinator groups. To test this, we studied pollination systems and floral traits along an elevational gradient on Mount Cameroon during wet and dry seasons. Using Random Forest models, allowing the ranking of traits by significance, we demonstrated that some floral traits are more important than others in shaping interactions and that these traits predict pollinators relatively well. However, the distribution and importance of traits varies under different environmental conditions. Our results imply the need to improve our trait-based understanding of plant-pollinator interactions to better inform the debate surrounding pollination syndrome hypothesis.

ecology↗

bioRxiv2020

Does rainforest biodiversity stand on the shoulders of giants? Effect of disturbances by forest elephants on trees and insects on Mount Cameroon

Natural disturbances are essential for dynamics of tropical rainforests, contributing to their tremendous biodiversity. In the Afrotropical rainforests, megaherbivores have played a key role before their recent decline. Although the influence of savanna elephants on ecosystems has been documented, their close relatives, forest elephants, remain poorly studied. Few decades ago, in the unique natural enclosure experiment on Mount Cameroon, West/Central Africa, the rainforests were divided by lava flows which are not crossed by the local population of forest elephants. We assessed communities of trees, butterflies and two ecological guilds of moths in disturbed and undisturbed forests split by the longest lava flow at upland and montane elevations. Altogether, we surveyed 32 forest plots resulting in records of 2,025 trees of 97 species, and 7,853 butterflies and moths of 437 species. The disturbed forests differed in reduced tree density, height, and high canopy cover, and in increased DBH. Forest elephants also decreased tree species richness and altered their composition, probably by selective browsing and foraging. The elephant disturbance also increased species richness of butterflies and had various effects on species richness and composition of all studied insect groups. These changes were most probably caused by disturbance-driven alterations of (micro)habitats and species composition of trees. Moreover, the abandonment of forests by elephants led to local declines of range-restricted butterflies. Therefore, the current appalling decline of forest elephant populations across the Afrotropics most probably causes important changes in rainforest biodiversity and should be reflected by regional conservation authorities.

ecology↗