Biology subjects

Mottl, O.

Publications and source records attributed to Mottl, O..

4 recordsLinked to original sources

bioRxiv2026

Spatial turnover amplifies with trophic level in hyperdiverse food webs

One of the most intuitive ideas in ecology is that diversity at lower trophic levels in food webs provides niches to support diversity at higher trophic levels. This accumulation of diversity can be limited by survival of species in the landscape, but revealing these limits has been challenging. We analyze spatial turnover in a hyperdiverse parasitoid-caterpillar-plant food web across 75,000 km2 of continuous lowland rainforest in Papua New Guinea. Species turnover across sites is higher in parasitoids than in their caterpillar hosts. Furthermore, turnover of interactions is also higher in parasitoid-caterpillar than caterpillar-plant networks. Spatial turnover thus amplifies upwards across trophic levels, forcing parasitoids to live closer to spatial persistence limits. Consequently, progressing rainforest fragmentation can especially endanger parasitoids.

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

VegVault database: linking global paleo-, and neo-vegetation data with functional traits and abiotic drivers

Understanding the dynamics and persistence of biodiversity patterns over short (contemporary) and long (thousands of years) time scales is crucial for predicting ecosystem changes under global climate and land-use changes. A key challenge is integrating currently scattered ecological data to assess complex vegetation dynamics over time. Here, we present VegVault, an interdisciplinary SQLite database that uniquely integrates paleo- and neo-ecological plot-based vegetation data on a global and millennial scale, directly linking them with functional traits, soil, and climate information. VegVault currently comprises data from BIEN, sPlotOpen, TRY, Neotoma, CHELSA, and WoSIS, providing a comprehensive and ready-to-use resource for researchers across various fields to address questions about past and contemporary biodiversity patterns and their abiotic drivers. To further support the usability of the data, VegVault is complemented by the {vaultkeepr} R package, enabling streamlined data access, extraction, and manipulation. This study introduces the structure, content, and diverse applications of VegVault, emphasizing its potential role in advancing ecological research to improve predictions of biodiversity responses to global climate change.

ecology↗

bioRxiv2020

Rate-of-change analysis in palaeoecology revisited: a new approach

AO_SCPLOWBSTRACTC_SCPLOWDynamics in the rate of compositional change (rate-of-change; RoC) of biotic or abiotic assemblages preserved in palaeoecological sequences, are thought to reflect changes due to exogenous drivers such as climate and human forcing as well as endogenous factors linked to local dynamics and biotic interactions. However, changes in sedimentation rates and sampling strategies can result in an uneven distribution of time intervals and are known to affect RoC estimates. Furthermore, there has been relatively little exploration of the implications of these challenges in quantifying RoC in palaeoecology. Here, we introduce R-Ratepol - an easy-to-use R package - that provides a robust numerical technique for detecting and summarising RoC patterns in complex multivariate time-ordered stratigraphical sequences. First, we compare the performance of common methods of estimating RoC and detecting periods of high RoC (peak-point) using simulated pollen-stratigraphical data with known patterns of compositional change and temporal resolution. In addition, we propose a new method of binning with a moving window, which shows a more than 5-fold increase in the correct detection of peak-points compared to the more traditional way of using individual levels. Next, we apply our new methodology to four representative European pollen sequences and show that our approach also performs well in detecting periods of significant compositional change during known onsets of human activity, early land-use transformation, and changes in fire frequency. Expanding the approach using R-Ratepol to open-access paleoecological datasets in global databases, such as Neotoma, will allow future palaeoecological and macroecological studies to quantify major changes in biotic composition or in sets of abiotic variables across broad spatio-temporal scales.

ecology↗