William K. Cornwell's research while affiliated with UNSW Sydney and other places

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 in 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 because of 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, because 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 be resolved only 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 This package should facilitate all research outputs that require diverse scientific name lists to be merged or outdated lists to be updated.

Deadwood represents globally important carbon, nitrogen, and phosphorus pools. Current wood nutrient dynamics models are extensions of those developed for leaf litter decomposition. However, tissue structure and dominant decomposers differ between deadwood and litter, and recent evidence suggests that decomposer stoichiometry in combination with litter quality may affect nutrient release. ● We quantified decomposition and release of carbon and nutrients from wood for two stem sizes of 22 tree species in a phosphorus-limited temperate forest near Sydney, Australia, and compared these to estimates from leaf litter literature. ● Following theory, nitrogen and phosphorus accumulated during early decomposition, but began to decline earlier than expected from work on leaves. Deadwood converged on higher carbon:nitrogen (50) and nitrogen:phosphorus (80) ratios than in leaf litter studies. Carbon:nitrogen at which nitrogen was released was higher in large stems (~135) than small stems (~95); both being higher than leaf litter. ● Drawing from the literature, these differences in nitrogen and phosphorus dynamics may be due to the identity of wood decomposers. Carbon:nitrogen of wood decomposers is higher than mean carbon:nitrogen of leaf litter decomposers, and this difference in stoichiometry may have important flow-on effects for nutrient cycles in forests.

Epiphytes are a large and understudied part of global diversity. Classic work by Gentry and Dodson argued that Neotropical, mid-elevation forests are centers of diversity for this growth form. We assessed this hypothesis with modern global geospatial and climatic datasets. By connecting growth form and occurrence data with climatic records at the same locations, we quantified spatial and climatic distributions of epiphyte species richness. Latitude was a powerful driver of epiphyte distributions, with peaks at the equator; here, epiphytes contributed significantly to vascular plant species richness with greatest prevalence at mid elevations and in the Neotropics. Climatically, precipitation was a stronger determinant than temperature as to where epiphytic species thrive. The study provides robust support for the hypotheses that plant diversity in Neotropical, mid-elevation forests is unusually concentrated in the epiphytic growth form, and the lower proportion of epiphytic diversity elsewhere may have both physiological or biogeographic explanations. The particular features of climate change in Neotropical mid-elevation habitats, and the implications for epiphyte diversity, are worthy of urgent research.

In macroecology, a classic empirical observation has been positive relationships between local abundance and species' range, known as the abundance-occupancy relationships (AORs). The existence of this empirical relationship has informed both theory development and applied questions. Notably, the spatial neutral model of biodiversity predicts AORs. Yet, based on the largest known meta-analysis of 16,562,995 correlations from ~3 billion bird observations, this relationship was indistinguishable from zero. Further, in a phylogenetic comparative analysis, species range had no predictive power over the global mean abundance of 7,464 bird species. We suggest that publication and confirmation biases may have created AORs, an illusion of a ‘universal’ pattern. This nullification highlights the need for ecologists to instigate a credibility revolution like psychology, where many classic phenomena have been nullified.

Sexual selection leads to the evolution of extravagant weaponry or ornamental displays, with the bearer of these traits gaining a reproductive advantage, potentially at a cost to the individual’s survival. The consequences of sexual selection can therefore impact species demographic processes and overall abundance. Currently, evidence connecting the effects of sexual selection to demography and abundance is conflicting. This study aims to rectify this issue by assessing the relationship between sexual selection and abundance in Passerines across the globe, importantly, accounting for migration and seasonality. We integrate a global citizen science dataset of bird observations with Passerine trait data to show that migration and seasonality are key moderators in the relationship between sexual selection and abundance. For resident Passerines, the relationship is consistently positive across the year, whereas for migrant Passerines, the relationship is overall neutral, with a significant negative dip during pre-breeding migration (for Northern Hemisphere Passerines). Our results suggest that sexual selection bolsters populations that experience less intense natural selection.

The ranges of many species globally have already shifted to maintain climatic equilibrium in the face of climate change. Biocrusts—soil surface dwelling communities of lichens, bryophytes and microbes—play important functional roles in many ecosystems, particularly in drylands. Compared to better studied animal and plant taxa, dryland biocrusts have different establishment requirements and have never been assessed for historical range shifts. Here, we revisited the sites (N = 204) of a 25‐year‐old biocrust survey across a large area (400,000 km²) of drylands in south‐eastern Australia. We used quadratic models to quantify changes in the climate niches of 15 lichen, eight moss and five liverwort taxa, as well as biocrust cover and richness. Our models showed that the observed climatic niches of most taxa have become hotter and drier in the past quarter century, yet the responses of the vast majority of taxa are consistent with remaining in the same geographic space. A similar pattern was observed at the community level, where the peak of biocrust cover and richness now occurs in a hotter, drier environment. Notable exceptions were the liverwort Riccia lamellosa and lichens in the genera Cladonia and Xanthoparmelia, which showed signs of contraction at their arid range edges. Unlike more mobile taxa, most biocrust species have yet to shift geographically and may already be lagging behind the pace of climate change. One explanation for the mortality lag is that long‐term climate variability in the system is extensive, which may have selected for the ability to withstand multi‐year warm periods as long as there is an eventual return to milder conditions. However, no forecasts of future climate include a return to milder conditions, suggesting there will be an eventual loss of ecosystem multifunctionality at the contracting front. Expansion lags are most likely due to delays in the mortality of competing vascular plants. Synthesis: Our study provides a valuable contribution to the knowledge of range shifts in understudied taxa and highlights a future need to promote the expansion of biocrusts to maintain the provision of ecosystem functions and services across their range.

Despite host‐fungal symbiotic interactions being ubiquitous in all ecosystems, understanding how symbiosis has shaped the ecology and evolution of fungal spores that are involved in dispersal and colonization of their hosts has been ignored in life‐history studies. We assembled a spore morphology database covering over 26,000 species of free‐living to symbiotic fungi of plants, insects and humans and found more than eight orders of variation in spore size. Evolutionary transitions in symbiotic status correlated with shifts in spore size, but the strength of this effect varied widely among phyla. Symbiotic status explained more variation than climatic variables in the current distribution of spore sizes of plant‐associated fungi at a global scale while the dispersal potential of their spores is more restricted compared to free‐living fungi. Our work advances life‐history theory by highlighting how the interaction between symbiosis and offspring morphology shapes the reproductive and dispersal strategies among living forms.

Leaf size varies within and between species, and previous work has linked this variation to the environment and evolutionary history separately. However, many previous studies fail to interlink both factors and are often data limited. To address this, our study developed a new workflow using machine learning to automate the extraction of leaf traits (leaf area, largest in-circle area and leaf curvature) from herbarium collections of Australian eucalypts (Eucalyptus, Angophora and Corymbia). Our dataset included 136,599 measurements, expanding existing data on this taxon’s leaf area by roughly 50-fold. With this dataset, we were able to confirm global positive relationships between leaf area and mean annual temperature and precipitation. Furthermore, we linked this trait-climate relationship to phylogeny, revealing large variation at the within-species level, potentially due to gene flow suppressing local adaptation. At deeper phylogenetic levels, the relationship strengthens and the slope converges towards the overall eucalypt slope, suggesting that the effect of gene flow relaxes just above the species level. The strengthening of trait-climate correlations just beyond the intraspecific level may represent a widespread phenomenon across various traits and taxa. Future studies may unveil these relationships with the larger sample sizes of new trait datasets generated through machine learning.

One way to improve the value of citizen science data for a specific aim is through promoting adaptive sampling, where the marginal value of a citizen science observation is dependent on existing data collected to address a specific question. Adaptive sampling could increase sampling at places or times—using a dynamic and updateable framework—where data are expected to be most informative for a given ecological question or conservation goal. We used an experimental approach to test whether the participants in a popular Australian citizen science project—FrogID—would follow an adaptive sampling protocol aiming to maximize understanding of frog diversity. After a year, our results demonstrated that these citizen science participants were willing to adopt an adaptive sampling protocol, improving the sampling of biodiversity consistent with a specific aim. Such adaptive sampling can increase the value of citizen science data for biodiversity research and open up new avenues for citizen science project design.