Biology subjects

Onstein, R.

Publications and source records attributed to Onstein, R..

4 recordsLinked to original sources

bioRxiv2025

Global convergence in wood evolution is driven by drought on continents and frost-free temperatures on islands

Phylogenetically derived woodiness (DW), the evolutionary reversion from herbaceousness to woodiness in angiosperms, is one of the most conspicuous characteristics of (sub)tropical island floras. Here, we show that DW across continents is more common than previously thought, especially in frost-free and open habitats with pronounced seasonal drought. Using a novel dataset on the evolution of woodiness in angiosperms, we discovered substantially more derived woody species (DWS) and independent evolutionary transitions on continents compared to islands (4,808 species and 513 transitions vs. 1,084 and 175, respectively). However, we identified more insular DWS hotspots (22) than the four continental DWS hotspots: the Andes, Southern Africa, the Old-World Dry Belt and Australia. A structural equation model controlling for total species richness suggests that aridity is the strongest predictor of the number of DWS on continents, while frost-free temperatures best predict DWS on islands. Precipitation seasonality and mean elevation emerge as additional significant predictors in both cases, with a further potential role for light-prone open habitats. In summary, the diverse global drivers behind the hundreds of independent woodiness shifts highlight the existence of various mechanisms that lead to increased wood formation in stems, confirming its adaptive value over evolutionary time.

evolutionary biology↗

bioRxiv2025

Functional traits drive speciation in tropical palms through complex interactions between genome size, adaptation and allometry

O_LIThe importance of functional trait evolution and genome size on plant speciation are well established, but their interactive effects remain untested in a single comparative macroevolutionary framework. C_LIO_LIWe integrated phylogenetic, trait and genome size data for palms (Arecaceae) - a large pantropical family (>2600 species) with 167-fold variation in trait and 60-fold variation in genome size. We used structural equation modelling to test three key 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). C_LIO_LIWe detected seven major speciation rate shifts during the ca. 110-million-year history of palms. Tip-derived speciation rates increased with faster evolution in leaves and plant height, supporting H1, whereas correlated evolution between trait evolution rates indirectly influenced speciation, supporting H2. Large genomes decreased plant height and stem diameter evolutionary rates, but increased leaf size evolution and speciation rates, thus partly supporting H3. C_LIO_LIOur findings illustrate how the complex interplay between genome size, allometry and trait evolvability affect speciation, emphasizing the importance of holistic approaches in macroevolution. Furthermore, our results point to potential general mechanisms driving speciation rates throughout the plant Tree of Life. C_LI

evolutionary biology↗

bioRxiv2025

The complex interaction between megaherbivores, climate and fire has shaped the evolution and distribution of plant spinescence across biogeographical realms

O_LIThe evolutionary arms race between plants and herbivores has led to numerous plant adaptations, including spinescence. However, whether spinescence evolved primarily in response to herbivory, or whether abiotic conditions also played a role, remains unknown. C_LIO_LIWe integrated phylogenetic, geographic, and trait data for 2,686 species of an ecologically diverse and spiny pantropical lineage - mimosoid legumes - with data for 235 extant and 185 extinct mammalian herbivores >10 kg. Using structural equation models, we assessed how herbivores, climate and fire directly and indirectly affected the proportion of spinescent mimosoids across global and continental assemblages. C_LIO_LIThe proportion of spinescent mimosoids in assemblages increased with extant and extinct herbivore richness, drought and heat, while fire influenced spinescence indirectly, by affecting herbivore richness. Notably, correlations of spinescence differed between Africa and America, with increasing importance of extinct herbivores in Africa, illustrating legacy effects on spinescence. C_LIO_LIMegaherbivores have shaped spinescence in mimosoids, especially in dry environments, where losing plant tissues is costly. Spinescence originated [~]35 Mya, with the transition of mimosoids to seasonally dry environments, pre-dating the Miocene expansion of savannas. Our study suggests that both long-term climatic transitions and the emergence of open, herbivore-rich landscapes played crucial roles in the evolution and distribution of spinescence. C_LI

evolutionary biology↗

bioRxiv2024

Body size is a better predictor of intra- than interspecific variation of animal stoichiometry across realms

Animal stoichiometry affects fundamental processes ranging from organismal physiology to global element cycles. However, it is unknown whether animal stoichiometry follows predictable scaling relationships with body mass and whether adaptation to life on land or water constrains patterns of elemental allocation. To test both interspecific and intraspecific body-size scaling relationships of the nitrogen (N), phosphorus (P), and N:P content of animals, we used a subset of the StoichLife database encompassing 9,933 individual animals (vertebrates and invertebrates) belonging to 1,543 species spanning 10 orders of magnitude of body size from terrestrial, freshwater, and marine realms. Across species, body mass did not explain much variation in %N and %P composition, although the %P of invertebrates decreased with size. The effects of body size on species elemental content were small in comparison to the effects of taxonomy. Body size was a better predictor of intraspecific than interspecific elemental patterns. Between 42 to 45% in intraspecific stoichiometric variation was explained by body size for 27% of vertebrate species and 35% of invertebrate species. Further, differences between organisms inhabiting aquatic and terrestrial realms were observed only in invertebrate interspecific %N, suggesting that the realm does not play an important role in determining elemental allocation of animals. Based on our analysis of the most comprehensive animal stoichiometry database, we conclude that (i) both body size and realm are relatively weak predictors of animal stoichiometry across taxa, and (ii) body size is a good predictor of intraspecific variation in animal elemental content, which is consistent with tissue-scaling relationships that hold broadly across large groups of animals. This research reveals a lack of general scaling patterns in the elemental content across animals and instead points to a large variation in scaling relationships within and among lineages.

ecology↗