Biology subjects

Stephens, R. E.

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

5 recordsLinked to original sources

bioRxiv2026

Contrasting climate signals between native and introduced annual and perennial floras

Annual versus perennial life histories represent a fundamental axis of plant strategy, with empirical evidence showing that the proportion of annuals is greater in hot, arid, or variable climates. Crucially, introduced species, a group that disproportionately includes annuals, are expanding in number and range across the globe. Whether introduced richness is governed by the same climatic controls as native richness remains untested at continental scales. For 19,299 native (12% annual) and 2,802 introduced (34% annual) Australian plant species, we show that native annual richness tracks climate far more tightly than introduced annual richness. Both floras largely follow the global pattern: the annual fraction rises in dry and seasonal climates. However, hotspots of native and introduced annual richness are completely different. Introduced annuals (28% of all annual species) concentrate in wet, populated areas with low precipitation seasonality, whereas native annual richness is fairly evenly distributed, with the highest diversity in the seasonal tropics. The current continental-scale pattern is thus the sum of a long interaction between the native floras life histories and in situ climate, with dynamic, path-dependent introductions layered on top. As introductions and range expansions continue, they will reshape the annual-to-perennial balance along pathways of human influence.

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↗

bioRxiv2024

APCalign: an R package workflow and app for aligning and updating flora names to the Australian Plant Census

Here we present "APCalign", an R package and accompanying browser-sourced application to align and update scientific names for Australian vascular plants to the most likely currently accepted name using the Australian Plant Census (APC) or a name in the Australian Plant Names Index (APNI). Scientific names are the label assigned to unique taxon concepts by the scientific community, but this common terminology is most useful if a taxon concept is consistently referred to by the same name. These links can be broken due to either spelling mistakes or taxonomic changes. Automated tools are required to resolve taxon lists, aligning and updating long lists of possibly erroneous scientific names to the most likely currently accepted names. It is essential that tools specific to the APC/APNI be developed, as these lists specify an endorsed national-level nomenclature used in government legislation and include the uniquely Australian concept of phrase names, absent in global taxonomic datasets. To align input names to names within the APC or APNI, "APCalign" works progressively through a sequence of checks that combine different permutations of the input name, exact versus fuzzy matches, matches that consider the entire name input versus a subset of words, and character strings that indicate a name can only be resolved to a genus or family. The aligned names are then, when possible, updated to a currently accepted taxon concept within the APC. This package should facilitate all research outputs that require diverse scientific name lists to be merged or outdated lists to be updated.

plant biology↗

bioRxiv2023

Insects pollinated flowering plants for most of angiosperm evolutionary history

O_LIPollination is a fundamental process driving the speciation of angiosperms (flowering plants). Most contemporary angiosperms are insect pollinated, but abiotic pollination by wind or water and vertebrate pollination by birds or mammals occurs in many lineages. We model the evolution of pollination across angiosperms and quantify the timing and environmental associations of pollination shifts. C_LIO_LIWe use a robust dated phylogeny and trait-independent species-level sampling across all families of angiosperms to model the evolution of pollination modes. Data on the pollination system or syndrome of 1160 species were collated from primary literature. C_LIO_LIAngiosperms were ancestrally insect pollinated, and insects have pollinated angiosperms for approximately 86% of angiosperm evolutionary history. Wind pollination evolved at least 42 times, with few reversals back to animal pollination. Transitions between insect and vertebrate pollination were more frequent: vertebrate pollination evolved at least 39 times from an insect pollinated ancestor with at least 26 reversals. The probability of wind pollination increases with habitat openness (measured by Leaf Area Index) and with distance from the equator. C_LIO_LIOur reconstruction of pollination across angiosperms sheds light on a key question in angiosperm macroevolution, highlighting the long history of interactions between insect pollinators and angiosperms still vital to global biodiversity today. C_LI

evolutionary biology↗

bioRxiv2021

Climate shapes flowering periods across plant communities

AimClimate shapes the composition and function of plant communities globally, but it remains unclear how this influence extends to floral traits. Flowering phenology, or the time period in which a species flowers, has well-studied relationships with climatic signals at the species level but has rarely been explored at a cross-community and continental scale. Here, we characterise the distribution of flowering periods (months of flowering) across continental plant communities encompassing six biomes, and determine the influence of climate on community flowering period lengths. LocationAustralia TaxonFlowering plants MethodsWe combined plant composition and abundance data from 629 standardised floristic surveys (AusPlots) with data on flowering period from the AusTraits database and additional primary literature for 2,983 species. We assessed abundance-weighted community mean flowering periods across biomes and tested their relationship with climatic annual means and the predictability of climate conditions using regression models. ResultsCombined, temperature and precipitation (annual mean and predictability) explain 29% of variation in continental community flowering period. Plant communities with higher mean temperatures and lower mean precipitation have longer mean flowering periods. Moreover, plant communities in climates with predictable temperatures and, to a lesser extent, predictable precipitation have shorter mean flowering periods. Flowering period varies by biome, being longest in deserts and shortest in alpine and montane communities. For instance, desert communities experience low and unpredictable precipitation and high, unpredictable temperatures and have longer mean flowering periods, with desert species typically flowering at any time of year in response to rain. Main conclusionsOur findings demonstrate the role of current climate conditions in shaping flowering periods across biomes, with implications under climate change. Shifts in flowering periods across climatic gradients reflect changes in plant strategies, affecting patterns of plant growth and reproduction as well as the availability of floral resources across the landscape.

ecology↗