Biology subjects

Potocky, P.

Publications and source records attributed to Potocky, P..

4 recordsLinked to original sources

bioRxiv2025

Effects of a native, dominant tree, Colophospermum mopane, on diversity of plants, insects, and vertebrates in South African savannas

Afrotropical savannas are biodiversity-rich ecosystems increasingly threatened by woody plant encroachment. In southern Africa, the leguminous tree Colophospermum mopane dominates over one-third of the savanna region and is projected to expand substantially under climate change. Yet, the consequences of its local dominance for biodiversity remain poorly understood. We conducted the first landscape-scale, multi-taxon assessment of mopanes bottom-up effects, analysing species richness and community composition of vascular plants, insects, birds, bats, and non-flying mammals across a gradient of mopane cover in Kruger National Park, South Africa. Our replicated plot-based study found that species richness of birds, mammals, bats, and insects declined significantly with increasing mopane dominance, with the steepest reductions in birds. Plant overall species richness was unaffected, although grasses showed a weak positive trend. We also revealed significant community compositional shifts in birds, bats, and mammals, while insect communities lost species without systematic composition change. Functional-group analyses confirmed species richness declines for herbivores across taxa, and for bird carnivores and omnivores, pointing to mopanes role as a strong ecological filter that reduces host plant and other resources availability, with consequences to the higher trophic levels. These results highlight mopane dominance as a potential driver of biodiversity simplification in African savannas, with cascading implications for ecosystem functioning. Given projections of mopane expansion and its socioeconomic value to local communities, management and policy must avoid promoting mopane dominance in land-use or restoration schemes. Safeguarding heterogeneous savanna mosaics will be essential for conserving biodiversity and ecosystem resilience under climate change.

ecology↗

bioRxiv2025

Elevational patterns in two groups of micromoths (Lepidoptera: Pterophoridae, Alucitidae) in tropical forests of Mount Cameroon

Tropical elevational gradients offer unique insights into ecological processes shaping biodiversity, although micromoths remain severely understudied, especially in the Afrotropics. We analysed species richness, community composition, and functional traits (elevational range size and wingspan) of two micromoth families, many-plumed moths (Alucitidae) and plume moths (Pterophoridae), along a complete forest gradient on Mount Cameroon, an Afrotropical biodiversity hotspot. Alucitidae exhibited a distinct mid-elevation diversity peak, mirroring common patterns in tropical butterflies and moths, whereas Pterophoridae showed an uncommon upslope increase in species richness. Both families demonstrated clear elevational turnover in community composition, indicative of strong environmental filtering. Additionally, community-weighted elevational range size and wingspan increased consistently with elevation, supporting Rapoports rule and Bergmanns cline, respectively. These patterns likely reflect interactions among climatic factors and environmental complexity, though the underlying mechanisms remain unresolved. Our findings reveal the unique communities of both mid- and high-elevation forests, as well as the distinctiveness of species-poor lowland assemblages. This elevational differentiation underscores the need for conservation across the full gradient and the vulnerability of endemic highland taxa to climate-driven range contractions. Comprehensive research on neglected tropical insect groups is urgently needed to better anticipate biodiversity responses to environmental change.

ecology↗

bioRxiv2024

Climate-driven vegetation characteristics shape phytophagous and carnivorous insect diversity in South African savannahs

Despite the recognized importance of insects in savannah ecosystems, the drivers of their diversity patterns remain poorly understood, particularly in the Afrotropical region. This study addresses this gap by investigating the impacts of climate, habitat, disturbance, and vegetation variables on the diversity of phytophagous moths (Lepidoptera) and carnivorous mantises (Mantodea) across 60 plots in Kruger National Park, South Africa. Based on an extensive dataset of 65,593 moth individuals representing 817 morphospecies and 3,511 mantis individuals representing 38 morphospecies, our results revealed plant communities as the fundamental driver of diversity for both insect groups. The effects of vegetation on insect diversity were indirectly influenced by climate, particularly mean temperature (negatively correlated with precipitation), through its impact on plant species richness. Additionally, a complex interplay among bedrock type, water availability, and disturbances from large herbivores and fire further shaped insect diversity. Our findings highlight the regions vulnerability to climate change, as decreasing precipitation and increasing temperatures were shown to alter vegetation composition and biomass, consequently affecting insect communities. Overall, our results emphasize the necessity of managing large herbivores and regulating fire regimes to maintain diverse vegetation, which is crucial for supporting insect diversity. Effective conservation strategies should prioritize balancing water availability and disturbance intensity, particularly in maintaining the health of seasonal rivers, to mitigate the adverse effects of climate change on these ecosystems.

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↗