Renske Emilie Onstein

Rapid adaptive evolution can increase the competitive ability of invasive species in their non-native ranges. However, whether this increase is a general response and what drives it remain uncertain because the evidence is largely based on studies with limited sampling, inadequate consideration of population co-ancestry, and oversimplified estimates of competitive ability. We conduct a large-scale glasshouse experiment testing the effects of competition and drought on 100 native and 165 non-native populations of Erigeron canadensis , all genotyped to account for co-ancestry. Plants from non-native populations are significantly more competitive against other species than the conspecifics from native populations under both mesic and dry conditions. Genetic clustering indicates that the rapid evolution of competitive ability occurs independently in two out of four clusters in the non-native range. This advantage is present only during interspecific interactions and is absent during intraspecific competition. Repeated evolution of increased competitive ability suggests that adaptation following introduction can reshape species interactions and promote invasion success, even under future drought conditions, highlighting the importance of rapid evolution in determining the ecological impacts of invasive plants.

Neotropical seasonally dry biomes are amongst the world's most threatened ecosystems and are predicted to lose more biodiversity with climate change. The capacity of natural populations to respond to these changes depends on their genetic variation, but is poorly understood in most Neotropical seasonally dry forest species. Here, we used genome‐wide single nucleotide polymorphism (SNP) data for 109 individuals across 12 Colombian populations of Enterolobium cyclocarpum , a widespread deciduous legume tree found in seasonally dry tropical forests, human‐disturbed and open landscapes from Central and Northern South America, to (1) explore population structure across the landscape, (2) determine local adaptation to heat and drought stress, and (3) assess genomic offset and adaptive potential under future climate change. Our results suggest clear genomic differentiation among regions and populations, as well as an uneven spatial distribution of adaptive alleles associated with drought and heat stress, together suggesting different degrees of local adaptation to climate across the landscape. Furthermore, all regions investigated (i.e., Caribbean, inter‐Andean valleys, and Orinoquía) showed limited adaptive potential under future climate change scenarios. For some regions, gene flow may help buffer the effects of environmental change by bringing in adaptive alleles, however, this will likely be insufficient to counteract predicted mal‐adaptation in certain regions, such as in the Orinoquía. Our results suggest that both barriers to gene flow (e.g., orography) and varying heat and drought stress conditions have shaped the genomic composition and adaptive potential of the species. Enterolobium cyclocarpum populations have adapted locally to current climate, but this adaptation may not be sufficient to cope with future climate change, particularly where population connectivity is low. Our findings have relevance for the conservation of species in highly threatened Neotropical biomes, such as seasonally dry tropical forests, which are expected to experience rising temperatures and greater drought under future climate change.

Pollination and seed dispersal by animals are key drivers of terrestrial biodiversity and ecosystem functioning. Effective mutualistic interactions rely heavily on temporal and functional- trait matching between plants and animals. While global warming is known to induce shifts in plant traits, the extent and direction in which higher temperatures may systematically alter flower and fruit traits across species in natural habitats remains poorly understood. Using elevation as a proxy for temperature across natural populations, we conducted a meta-analysis evaluating 21 quantitative functional traits (15 floral, 6 fruit) across 82 studies and 161 species. Standardized mixed-effects linear regression models revealed widespread, systemic responses to elevational temperature gradients in both reproductive structures. In flowers, higher temperatures were systematically associated with changes in petal and sepal width and length (and hence morphology), longevity, nectar volume, number of flowers, and inflorescence length. In fruits, elevation was associated with changes in vitamin C content, crop size, weight and width. Taken together, these results demonstrate that warming temperatures exert widespread, multi-axis effects on the morphology, availability, timing, and nutritional quality of both flowers and fleshy fruits. Given that flower and fruit traits are developmentally linked and co-determine animal visitor dynamics, these temperature-driven phenotypic shifts are likely to propagate cascading disruptions throughout plant–pollinator and plant–frugivore interaction networks under continued climate change.

Mountain regions harbor extraordinary biodiversity, yet the mechanisms underlying this pattern remain unclear. Here we use the phylogenetically and geographically replicated radiations of Berberis (barberries) in the Andes and Hengduan–Himalaya Mountains (HHM) to test how functional trait innovations, orogeny, and climate change influenced the buildup of species richness in each region. In barberries (Berberis), the successive evolution of deciduousness and small, densely-veined leaves enabled the lineage to take advantage of expanding alpine and subalpine habitats in the HHM during the Miocene. The resulting pulse in the origin of new species contrasts with the more modest rate of species accumulation in the Andes, where barberry species remained evergreen and the availability of high-elevation habitats was more limited. In this study, the phylogeny of barberries exemplifies context-dependent macroevolutionary dynamics, in which intrinsic innovations and extrinsic ecological opportunities interacted to generate exceptional plant diversity in a mountain hotspot.

Summary: The evolutionary arms race between plants and herbivores led to numerous plant adaptations, including spinescence. However, the balance between herbivory and abiotic conditions in the evolution of spinescence remains unclear. We integrated phylogenetic, geographic, and trait data for 2686 species of an ecologically diverse and spinescent pantropical lineage, mimosoid legumes, with distribution data on 368 extant and extinct mammalian herbivores ≥ 10 kg. Using structural equation models, we assessed how herbivores, climate, soil, and fire directly and indirectly affected the proportion of spinescent mimosoids across global and continental assemblages. Models incorporating extinct herbivore assemblages explained more variation in the proportion of spiny species than those based solely on extant herbivores. Dry‐season length and soil pH increased spinescence both directly and indirectly through their effects on herbivore richness. These abiotic effects exceeded herbivore effects at continental scales. Fire influenced spinescence only indirectly via its positive relationship with herbivore richness. Finally, spinescence evolved repeatedly across mimosoids from c. 35 million years ago, pre‐dating the Miocene savanna expansion. Our study suggests that past herbivore communities have left a lasting imprint on present‐day plant defence patterns and that long‐term climatic transitions and the emergence of open, herbivore‐rich landscapes played crucial roles in the evolution and distribution of spinescence.

Speciation shapes biodiversity, yet why some lineages diversify faster than others remains unclear. Theory predicts that traits promote ecological speciation through adaptation, but their evolvability (‘trait flexibility’) may be impacted by allometric and genomic constraints. Here we test this by integrating phylogenetic, trait and genome size data for palms (Arecaceae)—a large pantropical family (>2500 species) with 167-fold variation in certain traits (e.g. fruit size) and 60-fold genome size variation. Using structural equation modelling, we test three hypotheses: trait evolution promotes speciation (H1: trait flexibility hypothesis), and speciation and trait evolution rates are constrained by allometry (H2: allometric constraint hypothesis) and genome size (H3: large genome constraint hypothesis). We detected seven major speciation rate shifts during approximately 110-million-years of palm evolution. Tip-derived speciation rates increased with faster evolution in leaf size and plant height, supporting H1, whereas correlated evolution between all traits indirectly influenced speciation, supporting H2. Large genomes were associated with decreased plant height and stem diameter evolution rates supporting H3, but the genome size-speciation association was sensitive to phylogenetic autocorrelation. Our findings illustrate how the interplay between genome size, allometry and trait evolvability affect speciation, emphasizing the importance of holistic approaches for uncovering general mechanisms driving speciation throughout the Tree of Life.

Invasive plant species present a growing ecological and economic challenge, and often adapt rapidly to their novel environments through complex demographic and evolutionary processes. Invasion genomics offers powerful tools to disentangle these processes, but most studies rely on geographically narrow sampling across native and non‐native ranges. Erigeron canadensis is a cosmopolitan weed native to North America that has successfully invaded diverse climates worldwide. We used double‐digest restriction site‐associated DNA sequencing (ddRADseq) to investigate the genetic diversity and structure of 280 E. canadensis populations across the Northern Hemisphere. We found that native and non‐native populations maintained comparable genetic diversity. Population structure analyses revealed four genetic clusters that were mainly differentiated along latitudinal and aridity gradients. However, one cluster was strongly overrepresented in the non‐native compared to the native range. In the native range, genetic differentiation was shaped by spatial and environmental gradients, while in non‐native regions human‐mediated dispersal and repeated introductions disrupted environmentally driven genetic structure. Migration network analyses revealed limited intercontinental connectivity and a possible role of long‐distance dispersal in within‐range expansions. Genomic offset analyses showed that genotype‐environment mismatches in non‐native populations associated with reduced growth and reproduction. Together, our results indicate that the invasion dynamics of E. canadensis were driven by multiple introductions, population admixture, and lineage sorting, while some genotypes contributed disproportionately to the spread of this invader. The presence of apparent maladaptation suggests that even long‐established invaders may still be evolving in response to their novel environment, raising concerns about potential future expansions.

Despite widespread concern over global biodiversity loss, the balance between gains and losses within local plant communities remains contentious, largely due to a scarcity of integrative, long-term and large-scale analyses across different habitats and multiple facets of biodiversity. Here, we analyse 57,390 vegetation-plot time series of vascular plants across Europe to quantify the average and habitat-specific trends in taxonomic, functional, phylogenetic, and gamma diversity, alongside with changes in threatened Red List, non-native, and specialist versus generalist species. We find that, over the last 100 years, plant communities gained on average 0.7% in vegetation cover and 0.2% in species number per year, associated with gains in functional and phylogenetic diversity, non-native, Red List, and generalist species. Diversity changes are most pronounced in mire and wetland communities. Differences among habitat types and habitat-change trajectory (stable, successional, disturbed), together with the most recent observation year, explain 2.1%–36.6% of the variation in diversity trends. Habitat-specific gamma diversity showed no general trends and only increased in stable grasslands and successional sparsely vegetated habitats. By integrating habitat types and change trajectories, we reconcile some of the conflicting narratives on local biodiversity change in favour of a more nuanced understanding of the observed variation in local biodiversity change.

Aim: Long distance dispersal and the ability to delay germination under unfavourable conditions (dormancy) are critical for plant persistence and range expansion. However, how dispersal syndrome and dormancy interactively shape maximum dispersal distance and species range size across climate regions remains unclear. We tested the hypothesis that a trade‐off between dormancy and dispersal distance operates differently in animal‐mediated versus abiotic dispersal systems, and that climate modulates their influence on range size. Location: Global. Time Period: Current. Major Taxa Studied: Seed plants. Methods: We compiled data on dormancy, dispersal syndrome, maximum seed dispersal distance and range size for 631 plant species across 118 families worldwide. We used linear mixed effects models to examine how dormancy and dispersal syndromes interactively shape seed dispersal distance and range size across tropical and temperate regions. Results: Non‐dormant species had larger maximum dispersal distances than dormant species, but only in abiotic dispersal systems, consistent with a trade‐off between dispersal and persistence traits (dormancy). In contrast, animal‐mediated dispersal led to larger dispersal distances than abiotic dispersal, regardless of whether species were dormant or not. The influence of dormancy and dispersal syndrome on range size was climate‐dependent. In tropical regions, animal‐mediated dispersal enhanced range size, while dormancy had little effect. In temperate regions, maximum seed dispersal distance was positively associated with range size, but neither dormancy nor animal‐mediated dispersal significantly affected range size. Main Conclusions: The interplay between seed dormancy and dispersal syndromes shapes seed dispersal distance and species range size in climate‐specific ways. Animal‐mediated dispersal promotes larger maximum dispersal distances and larger range sizes in tropical regions. In contrast, in abiotic dispersal systems, dormancy leads to relatively small dispersal distances, but dormancy itself does not affect range sizes in temperate or tropical regions. Understanding dispersal‐dormancy dynamics is essential for predicting how plants will respond to environmental changes.