Biology subjects

Pysek, P.

Publications and source records attributed to Pysek, P..

9 recordsLinked to original sources

bioRxiv2026

Global Convergence of Plant Functional Trait Composition in the Anthropocene

Since the onset of European colonial expansion, humans have accelerated species migration across continents, reshaping plant functional composition and associated ecosystem processes. Plant functional traits-such as leaf area, plant height, or rooting depth-are structured along major axes of variation, including size and leaf economics, that reflect ecological strategies. While human-mediated changes in this trait space have been documented regionally or for specific taxa, there exists no global, grid cell-level quantification of past shifts across major axes of trait variation. Here, we link global citizen science plant occurrence data with data on 37 above- and below-ground traits, and information on native and introduced status for each occurrence. Using dimension-reduction on grid cell-level trait means and introduced species status as a proxy for anthropogenic change, we identify three major axes of functional variation: the size, leaf economics, and life-span axes. By comparing past (native-only) and present-day trait distributions in 3D trait space and geographically, we find prominent region-specific shifts along all three axes. Overall, functional composition converges toward (mostly) smaller, more acquisitive, and shorter-lived assemblages, with region-specific differences in which axis shifts are most pronounced. These results provide the first global estimate of how human-mediated plant introductions have altered ecosystem functional composition in the past centuries, highlighting the spatial patterns and trait dimensions most affected by anthropogenic pressures.

ecology↗

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

Global disruption of plant biogeography by non-native species

Biogeographical regions reflect differences in biotic composition resulting from long-term isolation and biogeographical processes, but how human-mediated introductions of non-native species have altered these biogeographical patterns remains unclear. Using global distribution data of 279,441 native and 10,067 non-native seed plant species, we analyzed the impact of species introductions on global organization of biogeographical regions. We show that species introductions have disrupted plant biogeography, causing the loss of distinct floristic realms and subrealms. Due to the impact of non-native species, geographic proximity and dispersal barriers are less important-- particularly as trade-facilitated species exchange drives floristic homogenization--while environmental factors remain critical in structuring floristic regions. Our findings reveal that plant introductions erode biogeographical distinctness and highlight the urgent need for coordinated action to protect native biotas.

ecology↗

bioRxiv2025

Jack of all trades and master of most: Carpobrotus taxa show no trade-off in reproductive strategies

O_LIThe ability to reproduce via multiple strategies is crucial for the invasion success of alien plant species. Here, we use Carpobrotus taxa (species and hybrids) to explore how trade-offs between and within these strategies may influence plant invasion dynamics. Native to South Africa, Carpobrotus plants are globally prominent in coastal ecosystems, reproducing by seed and clonally, and frequently hybridizing in both native and introduced regions. Three genetically distinct clusters were previously identified, with evidence of hybridization within and between these clusters in native and non-native ranges. C_LIO_LIWe collected fruit samples from populations representing the genetic clusters and their hybrids across native and non-native ranges (i.e., Europe, California, and New Zealand). These genetic clusters reflect the complex taxonomy of Carpobrotus, where species boundaries are unclear due to hybridization and morphological similarity. We then assessed seed set, seed mass, germination rates, and early growth under varying abiotic conditions alongside genetic estimates of clonality. C_LIO_LIGermination rates were influenced by temperature, moisture, and nutrient levels. Non-native populations demonstrated higher seed set, seed mass, and germination success compared to native populations, indicating a stronger investment in sexual reproduction. These populations also showed higher levels of clonality, shown by lower genotypic richness, suggesting that both reproductive strategies enhance invasive potential. C_LIO_LIHigh-clonality populations produced more seeds, demonstrating that the two reproductive strategies are not mutually exclusive. These results highlight the importance of multiple reproductive strategies for the establishment and spread of Carpobrotus taxa and provide insights into the mechanisms driving their global success. C_LI

plant biology↗

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↗

bioRxiv2022

Phylogenetic endemism of the world's seed plants

Assessing phylogenetic endemism, i.e., the distribution of geographically restricted and evolutionarily unique species, is key to understanding biogeographic patterns and processes and critical for global conservation planning. Here, we quantified the geographic distribution and drivers of phylogenetic endemism for ~320,000 seed plants worldwide and identified centers and drivers of evolutionarily young (neoendemism) and evolutionarily old endemism (paleoendemism). Tropical and subtropical islands of the Southern Hemisphere as well as tropical mountainous regions displayed the worlds highest phylogenetic endemism. Tropical moist forests (e.g. Amazonia) and continental islands in south-east Asia emerged as centers of paleoendemism, while both high neo- and paleoendemism were found on ancient continental fragment islands (e.g. Madagascar) and in Mediterranean-climate regions. Global variation in phylogenetic endemism was best explained by a combination of past and present environmental factors (80.3% - 88.1% of variance explained). Geographic isolation and environmental heterogeneity emerged as primary drivers promoting high phylogenetic endemism. Also, warm and wet climates with long-term climatic stability showed a significant positive effect. However, environmental effects on phylogenetic endemism varied with geographic isolation, reflecting the unique evolutionary and biogeographic dynamics on oceanic islands. Long-term climatic stability promoted the persistence of paleoendemics, while isolation promoted higher neoendemism leading to oceanic islands and tropical mountainous regions being centers of both neo- and paleoendemism. Our study provides new insights into the evolutionary underpinnings of biogeographic patterns in seed plants, and by identifying areas of high evolutionary and biogeographic uniqueness, it may serve as a key resource for setting global conservation priorities.

ecology↗

bioRxiv2022

Machine learning improves global models of plant diversity

Despite the paramount role of plant diversity for ecosystem functioning, biogeochemical cycles, and human welfare, knowledge of its global distribution is incomplete, hampering basic research and biodiversity conservation. Here, we used machine learning (random forests, extreme gradient boosting, neural networks) and conventional statistical methods (generalised linear models, generalised additive models) to model species richness and phylogenetic richness of vascular plants worldwide based on 830 regional plant inventories including c. 300,000 species and predictors of past and present environmental conditions. Machine learning showed an outstanding performance, explaining up to 80.9% of species richness and 83.3% of phylogenetic richness. Current climate and environmental heterogeneity emerged as the primary drivers, while past environmental conditions left only small but detectable imprints on plant diversity. Finally, we combined predictions from multiple modelling techniques (ensemble predictions) to reveal global patterns and centres of plant diversity at multiple resolutions down to 7,774 km2. Our predictive maps provide the most accurate estimates of global plant diversity available to date at grain sizes relevant for conservation and macroecology.

ecology↗

bioRxiv2019

Effects of land-use change and related pressures on alien and native subsets of island communities

Island species and habitats are particularly vulnerable to human disturbances, and anthropogenic changes are increasingly overwriting natural island biogeographic patterns. However, quantitative comparisons of how native and alien assemblages respond to human disturbances are scarce. Using data from 6,242 species of vertebrates, invertebrates and plants, from 7,718 sites on 81 islands, we model how land-use change, human population density and distance to the nearest road affect local assemblages of alien and native species on islands. We found that land-use change reduces both richness and abundance of native species, whereas the number and abundance of alien species are high in plantation forests and agricultural or urban sites. In contrast to the long-established pattern for native species (i.e., decline in species number with island isolation), more isolated islands have more alien species across most land uses than do less isolated islands. We show that alien species play a major role in the turnover of island assemblages: our models show that aliens outnumber natives among the species present at disturbed sites but absent from minimally-disturbed primary vegetation. Finally, we found a homogenization pattern for both native and alien assemblages across sites within most land uses. The declines of native species on islands in the face of human pressures, and the particular proneness to invasions of the more remote islands, highlight the need to reduce the intensity of human pressures on islands and to prevent the introduction and establishment of alien species.

ecology↗

bioRxiv2019

Disharmony of the world’s island floras

Disharmony is a key concept in island biology that describes the biased representation of higher taxa on islands compared to their mainland source regions. Although differential colonization success of taxa is predicted by selective dispersal, environmental and biotic filtering, the empirical evidence for disharmony remains largely anecdotal. Here, we develop a novel method for delineating island source regions and present the first global quantitative assessment of island disharmony. We analyzed the overall compositional bias of 320 island floras and examined the over- or under-representation on islands for 450 plant families. We found that the compositional bias of island floras is strongly predicted by geographical and climatic island characteristics (isolation, area, geologic origin, temperature, precipitation), whereas the representation of individual families is only weakly related to family-specific characteristics (family size, family age, taxonomic group, functional traits), indicating that the taxonomic scope of the disharmony concept has historically limited its wider applicability. Our results provide a strong foundation for integrating disharmony with quantitative functional and phylogenetic approaches in order to gain a deeper understanding of assembly processes on islands.

ecology↗