Biology subjects

Onstein, R. E.

Publications and source records attributed to Onstein, R. E..

14 recordsLinked to original sources

bioRxiv2026

Effects of temperature gradient on flower and fruit traits: a meta analysis

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.

ecology↗

bioRxiv2025

Rampant transitions between dispersal syndromes duringangiosperm evolution

O_LIAngiosperms have evolved a diverse range of seed dispersal syndromes that have undoubtedly played a key role in their evolutionary history and rise to dominance. However, it remains largely unknown how ancestral angiosperm seeds were dispersed, when and how frequent dispersal-related characters and syndromes evolved, and whether these syndromes facilitated biome and pollination mode transitions. C_LIO_LIWe integrated a large phylogeny and several dispersal-related characters for >1200 species representing all extant angiosperm families. We used phylogenetic comparative methods to infer ancestral states of major angiosperm clades, trends in the evolution of dispersal syndromes, and evolutionary correlations between dispersal syndromes, biomes and pollination modes. C_LIO_LIWe show that angiosperms were ancestrally most likely animal-dispersed (zoochory) and had fleshy, indehiscent fruits. Over macroevolutionary time, frequent transitions between dispersal syndromes occurred, often with non-specialised (autonomous) dispersal as an intermediate state. Finally, we found that dispersal syndrome evolution affected transition rates among biomes and among pollination modes. C_LIO_LIThe number of dispersal syndrome transitions exceeded pollination mode transitions by a factor of five, emphasizing lability in dispersal syndrome evolution. The progressive evolution of diaspore complexity led to frequent and repeated evolution of dispersal syndromes, critical for the colonization of angiosperms across modern biomes. C_LI

evolutionary biology↗

bioRxiv2025

Legacy of the lost and pressure of the present: Malagasy plant seeds retain megafauna dispersal signatures but downsize under human footprint

Past megafaunal extinctions and ongoing declines of remaining large-bodied frugivores limit the dispersal of large-seeded plants, contributing to their (local) demise, thereby downsizing plant seeds across assemblages. Here, we test this hypothesis by integrating trait and distribution data for 2,852 endozoochorous plant species, 48 extant and 15 extinct frugivore species across 361 assemblages on Madagascar. Using structural equation models, we show that mega-seeded plants - with seeds that are too large to be swallowed by any extant Malagasy frugivore - have larger seeds in assemblages where past megafrugivores were larger, highlighting the legacy of past interactions on persisting mega-seeded plants. Furthermore, human footprint reduces seed sizes directly and indirectly by downsizing of extant frugivore in the assemblages. Such human-driven seed downsizing can lead to erosions of important ecosystem functions such as tropical forest carbon storage.

ecology↗

bioRxiv2023

The evolutionary age-range size relationship is modulated by insularity and dispersal in plants and animals

Earth is home to millions of plant and animal species, with more than 40 thousand species facing extinction worldwide (Diaz et al. 2019). Species range size is particularly important in this context because it influences extinction risk (Purvis et al. 2000, Gaston & Fuller 2009), but the causes underlying the wide natural variation in range size remain poorly known. Here, we investigate how evolutionary age is related to present-day range size for over 25,000 species of mammals, birds, reptiles, amphibians, reef fishes, and plants. We show that, on average, older species have significantly larger ranges, but the effect of age on range size is modulated by clade, geographical context and dispersal ability. Specifically, age does not affect range size for island species, because islands limit dispersal and hence range size, regardless of species age. Furthermore, species from clades with high dispersal capabilities obtain large ranges faster, thereby further neutralizing the relationship between age and range size. Our results can help supporting global conservation priorities, by showing that species that are young, occupy islands, and/or are dispersal limited often have small ranges and therefore increased extinction risk.

ecology↗

bioRxiv2023

Rapid in-situ diversification rates in Rhamnaceae explain the parallel evolution of high diversity in temperate biomes from global to local scales

O_LIThe macroevolutionary processes that have shaped biodiversity across the temperate realm remain poorly understood and may have resulted from evolutionary dynamics related to diversification rates, dispersal rates, and colonization times, closely coupled with Cenozoic climate change. C_LIO_LIWe integrated phylogenomic, environmental ordination, and macroevolutionary analyses for the cosmopolitan angiosperm family Rhamnaceae to disentangle the evolutionary processes that have contributed to high species diversity within and across temperate biomes. C_LIO_LIOur results show independent colonization of environmentally similar but geographically separated temperate regions mainly during the Oligocene, consistent with the global expansion of temperate biomes. High global, regional, and local temperate diversity was the result of high in-situ diversification rates, rather than high immigration rates or accumulation time, except for Southern China, which was colonized much earlier than other regions. The relatively common lineage dispersals out of temperate hotspots highlights strong source-sink dynamics across the cosmopolitan distribution of Rhamnaceae. C_LIO_LIThe proliferation of temperate environments since the Oligocene may have provided the ecological opportunity for rapid in-situ diversification of Rhamnaceae across the temperate realm. Our study illustrates the importance of high in-situ diversification rates for the establishment of modern temperate biomes and biodiversity hotspots across spatial scales. C_LI

evolutionary biology↗

bioRxiv2023

Life on the edge: a new toolbox for population-level climate change vulnerability assessments

O_LIGlobal change is impacting biodiversity across all habitats on earth. New selection pressures from changing climatic conditions and other anthropogenic activities are creating heterogeneous ecological and evolutionary responses across many species geographic ranges. Yet we currently lack standardised and reproducible tools to effectively predict the resulting patterns in species vulnerability to declines or range changes. C_LIO_LIWe developed an informatic toolbox that integrates ecological, environmental and genomic data and analyses (environmental dissimilarity, species distribution models, landscape connectivity, neutral and adaptive genetic diversity and genotype-environment associations) to estimate population vulnerability. In our toolbox, functions and data structures are coded in a standardised way so that it is applicable to any species or geographic region where appropriate data are available, for example individual or population sampling and genomic datasets (e.g. RAD-seq, ddRAD-seq, whole genome sequencing data) representing environmental variation across the species geographic range. C_LIO_LIWe apply our toolbox to a georeferenced genomic dataset for the East African spiny reed frog (Afrixalus fornasini) to predict population vulnerability, as well as demonstrating that range loss projections based on adaptive variation can be accurately reproduced using data for two European bat species (Myotis escalerai, and M. crypticus). C_LIO_LIOur framework sets the stage for large scale, multi-species genomic datasets to be leveraged in a novel climate change vulnerability framework to quantify intraspecific differences in genetic diversity, local adaptation, range shifts and population vulnerability based on exposure, sensitivity, and range shift potential. C_LI

evolutionary biology↗

bioRxiv2023

Genomic signatures of past megafrugivore-mediated dispersal in Malagasy palms

O_LISeed dispersal is a key process in the generation and maintenance of genetic diversity and genetic differentiation of plant populations in tropical ecosystems. During the Last Quaternary, most seed-dispersing megafauna was lost globally, but whether this has caused dispersal limitation, loss of genetic diversity, and increased genetic differentiation between plant populations with large, megafaunal fruits (i.e., > 4 cm - megafruits) remains unclear. C_LIO_LIHere, we assessed whether megafrugivore extinctions in Madagascar (e.g., giant lemurs, elephant birds) have affected the genetic diversity and genetic differentiation of four animal-dispersed Malagasy palm (Arecaceae) species with large (Borassus madagascariensis), medium-sized (Hyphaene coriacea, Bismarckia nobilis), and small (Chrysalidocarpus madagascariensis) fruits. We integrated double-digest restriction-site-associated DNA sequencing (ddRAD) of 167 individuals from 25 populations with (past) distribution ranges for extinct and extant seed-dispersing animal species, climate and human impact data, and applied linear mixed-effects models to explore the drivers of variation in genetic diversity and genetic differentiation across Malagasy palm populations. C_LIO_LIWe detected higher genetic diversity in species with megafruits than in the species with small fruits, and genetic differentiation was lowest for the human-used medium-sized megafruit species. Furthermore, we found that a higher number of shared extinct megafrugivore species between palm population pairs was associated with less genetic differentiation, indicating higher gene flow, whereas no relationship with extant frugivores - that are not able to swallow and disperse the seeds - was found. Finally, genetic diversity decreased with road density, whereas genetic differentiation decreased with increasing human population density, but only for populations with megafruits. C_LIO_LIOur results suggest that the legacy of megafrugivores regularly achieving long dispersal distances is still reflected in the genetic diversity and genetic differentiation of palms that were formerly dispersed by such large animals. Furthermore, high genetic diversity and low genetic differentiation were possibly maintained after the megafauna extinctions through human-mediated dispersal, long generation times, and long lifespans of these palms. Our study illustrates how integrating genetics with ecological data on species interactions, climate, and human impact, provides novel insights into the consequences of megafauna extinctions for plants with megafruits. C_LI

evolutionary biology↗

bioRxiv2022

Plant longevity, drought and island isolation favoured rampant evolutionary transitions towards insular woodiness

Insular woodiness (IW)--the evolutionary transition from herbaceousness towards woodiness on islands--is one of the most iconic features of island floras. Since pioneering work by Darwin and Wallace, five IW drivers have been proposed: (i) favourable aseasonal climate and (ii) lack of large native herbivores promote plant longevity that (iii) results in prolonged flowering favouring outcrossing. Alternatively, (iv) competition for sunlight requires taller and stronger stems, and (v) drought favours woodiness to safeguard root-to-shoot water transport. However, information on the occurrence of IW is fragmented, hampering tests of these potential drivers. Here, we identify 1,097 insular woody species (IWS) on 375 islands, and infer at least 175 evolutionary transitions on 31 archipelagos, concentrated in six angiosperm families. Structural equation models reveal that the IWS richness on oceanic islands correlates with aseasonal favourable climate, followed by increased drought and island isolation (approximating competition). When continental islands are included, reduced herbivory pressure by large native mammals, increased drought and island isolation are most relevant. The repeated evolution of IW opens promising avenues to disentangle the variation in gene regulatory networks triggering wood formation, and emphasize individual archipelagos as laboratories of evolution, where similar environmental conditions replicate convergent evolution of similar traits.

evolutionary biology↗

bioRxiv2021

Understanding the relationship between dispersal and range size

Understanding what drives the vast variability in species range size is still an outstanding question. Among the several processes potentially affecting species ranges, dispersal is one of the most prominent hypothesized predictors. However, the theoretical expectation of a positive dispersal-range size relationship has received mixed empirical support. Here, we synthesized results from 84 studies to investigate in which context dispersal is most important in driving species range size. We found that dispersal traits - proxies for dispersal ability - explain range sizes more often in temperate and subtropical regions than in tropical regions, when considering multiple components of dispersal, and when investigating a large number of species to capture dispersal and range size variation. In plants, positive effects of dispersal on range size were less often detected when examining broad taxonomic levels. In animals, dispersal is more important for range size increase in ectotherms than in endotherms. Our synthesis emphasizes the importance of considering different aspects of the dispersal process -departure, transfer, settlement-, niche aspects and evolutionary components, like time for range expansion and past geological-environmental dynamics. We therefore call for a more integrative view of the dispersal process and its causal relationship with range size.

ecology↗

bioRxiv2020

Late Quaternary habitat suitability models for chimpanzees (Pan troglodytes) since the Last Interglacial (120,000 BP)

AimPaleoclimate reconstructions have enhanced our understanding of how past climates may have shaped present-day biodiversity. We hypothesize that habitat stability in historical Afrotropical refugia played a major role in the habitat suitability and persistence of chimpanzees (Pan troglodytes) during the late Quaternary. We aimed to build a dynamic model of changing habitat suitability for chimpanzees at fine spatio-temporal scales to provide a new resource for understanding their ecology, behaviour and evolution. LocationAfrotropics. TaxonChimpanzee (Pan troglodytes), including all four subspecies (P. t. verus, P. t. ellioti, P. t. troglodytes, P. t. schweinfurthii). MethodsWe used downscaled bioclimatic variables representing monthly temperature and precipitation estimates, historical human population density data and an extensive database of georeferenced presence points to infer chimpanzee habitat suitability at 62 paleoclimatic time periods across the Afrotropics based on ensemble species distribution models. We mapped habitat stability over time using an approach that accounts for dispersal between time periods, and compared our modelled stability estimates to existing knowledge of Afrotropical refugia. Our models cover a spatial resolution of 0.0467 degrees (approximately 5.19 km2 grid cells) and a temporal resolution of every 1,000-4,000 years dating back to the Last Interglacial (120,000 BP). ResultsOur results show high habitat stability concordant with known historical forest refugia across Africa, but suggest that their extents are underestimated for chimpanzees. We provide the first fine-grained dynamic map of historical chimpanzee habitat suitability since the Last Interglacial which is suspected to have influenced a number of ecological-evolutionary processes, such as the emergence of complex patterns of behavioural and genetic diversity. Main ConclusionsWe provide a novel resource that can be used to reveal spatio-temporally explicit insights into the role of refugia in determining chimpanzee behavioural, ecological and genetic diversity. This methodology can be applied to other taxonomic groups and geographic areas where sufficient data are available.

ecology↗

bioRxiv2020

Half of the world's tree biodiversity is unprotected and is increasingly threatened by human activities

Although trees are key to ecosystem functioning, many forests and tree species across the globe face strong threats. Preserving areas of high biodiversity is a core priority for conservation; however, different dimensions of biodiversity and varied conservation targets make it difficult to respond effectively to this challenge. Here, we (i) identify priority areas for global tree conservation using comprehensive coverage of tree diversity based on taxonomy, phylogeny, and functional traits; and (ii) compare these findings to existing protected areas and global biodiversity conservation frameworks. We find that ca. 51% of the top-priority areas for tree biodiversity are located in current protected areas. The remaining half top-priority areas are subject to moderate to high human pressures, indicating conservation actions are needed to mitigate these human impacts. Our findings emphasize the effectiveness of using tree conservation priority areas for future global conservation planning.

ecology↗

bioRxiv2019

The role of preadaptation, propagule pressure and competition in the colonization of new habitats

To successfully colonize new habitats, organisms not only need to gain access to it, but also need to cope with the selective pressures imposed by the local biotic and abiotic conditions. The number of immigrants, the preadaptation to the local habitat and the presence of competitors are important factors determining the success of colonization. Here, using an experimental set-up, we test the combined effect of propagule pressure, preadaptation and interspecific competition on the colonization success of new habitats using the two-spotted spider mite (Tetranychus urticae) as our model system and the red spider mite (Tetranychus evansi) as a competitor. Our results show that propagule pressure and preadaptation positively affect colonization success. More successful populations reach larger final population sizes either by having higher per capita growth rate (due to preadaptation effect) or by starting a population with a larger number of individuals. Although populations are more successful colonizing non-competitive environments than competitive ones, propagule pressure and preadaptation counteract the negative effects of competition, promoting colonization success. Our results show the importance of propagule pressure and preadaptation to cope both with the exigencies of the new environment and the community context for successful colonization of new habitats.

evolutionary biology↗

bioRxiv2019

Diversification in evolutionary arenas -- assessment and synthesis

Understanding how and why rates of evolutionary diversification vary is a key issue in evolutionary biology, ecology, and biogeography, and the metaphorical concepts of adaptive radiation and evolutionary stasis describe two opposing aspects causing variation in diversification rates. Here we review the central concepts in the evolutionary diversification literature and synthesize these into a simple, general framework for studying rates of diversification and quantifying their underlying dynamics, which can be applied across clades and regions and across spatial and temporal scales. Our framework describes the diversification rate (d) as a function of the abiotic environment (a), the biotic environment (b) and clade-specific phenotypes or traits (c); thus d[~]a,b,c. We refer to the four components (a-d) and their interactions collectively as the Evolutionary Arena. We outline analytical approaches to this framework and present a case study on conifers, for which we parameterise the general model. We also discuss three conceptual examples: the Lupinus radiation in the Andes in the context of emerging ecological opportunity and fluctuating connectivity due to climatic oscillations; oceanic island radiations in the context of island formation and erosion; and biotically driven radiations of the Mediterranean orchid genus Ophrys. The results of the conifer case study are consistent with the long-standing scenario that low competition and high rates of niche evolution promote diversification. The conceptual examples illustrate how using the synthetic Evolutionary Arena framework helps to identify and structure future directions for research on evolutionary radiations. In this way, the Evolutionary Arena framework promotes a more general understanding of variation in evolutionary rates by making quantitative results comparable between case studies, thereby allowing new syntheses of evolutionary and ecological processes to emerge.

evolutionary biology↗

bioRxiv2019

The flickering connectivity system of the north Andean paramos

ABSTRACT AND KEYWORDSO_ST_ABSAimC_ST_ABSTo quantify the effect of Pleistocene climate fluctuations on habitat connectivity across paramos in the Neotropics.\n\nLocationThe Northern Andes\n\nMethodsThe unique paramos habitat underwent dynamic shifts in elevation in response to changing climate conditions during the Pleistocene. The lower boundary of the paramos is defined by the upper forest line, which is known to be highly responsive to temperature. Here we reconstruct the extent and connectivity of paramos over the last 1 million years (Myr) by reconstructing the UFL from the long fossil pollen record of Funza09, Colombia, and applying it to spatial mapping on modern topographies across the Northern Andes for 752 time slices. Data provide an estimate of how often and for how long different elevations were occupied by paramos and estimates their connectivity to provide insights into the role of topography in biogeographic patterns of paramos.\n\nResultsOur findings show that connectivity amongst paramos of the Northern Andes was highly dynamic, both within and across mountain ranges. Connectivity amongst paramos peaked during extreme glacial periods but intermediate cool stadials and mild interstadials dominated the climate system. These variable degrees of connectivity through time result in what we term the flickering connectivity system. We provide a visualization (video) to showcase this phenomenon. Patterns of connectivity in the Northern Andes contradict patterns observed in other mountain ranges of differing topographies.\n\nMain conclusionsPleistocene climate change was the driver of significant elevational and spatial shifts in paramos causing dynamic changes in habitat connectivity across and within all mountain ranges. Some generalities emerge, including the fact that connectivity was greatest during the most ephemeral of times. However, the timing, duration and degree of connectivity varied substantially among mountain ranges depending on their topographic configuration. The flickering connectivity system of the paramos uncovers the dynamic settings in which evolutionary radiations shaped the most diverse alpine biome on Earth.

ecology↗