Science Enabled by Specimen Data

Roberts, J., and S. Florentine. 2022. Biology, distribution and management of the globally invasive weed Solanum elaeagnifolium Cav (silverleaf nightshade): A global review of current and future management challenges. Weed Research. https://doi.org/10.1111/wre.12556

Solanum elaeagnifolium Cav (silverleaf nightshade) is a deep-rooted, multi-stemmed, perennial, herbaceous woody plant that has been observed to threaten agricultural and native biodiversity worldwide. It is widely agreed that without efficient integrated management, S. elaeagnifolium will continue to cause significant economic and environmental damage across multiple scales. It is estimated that the annual economic impact of S. elaeagnifolium in Australia exceeds AUD $62 million, with this figure likely to be much higher in other countries invaded by this plant. It can also tolerate a high level of abiotic stress and survive in a range of temperatures (below freezing point to 34°C) and areas with an average yearly rainfall between 250 and 600 mm. Its extensive deep taproot system is capable of regenerating asexually and with its many seed dispersal mechanisms; it can quickly spread and establish itself within a region. This makes containment and management of the species especially challenging. Previous management has largely been focused on biological control, competition, essential oils, grazing pressure, herbicide application and manual removal. Despite the large range of available management techniques, there has been little success in the long-term control of S. elaeagnifolium, and only a handful of methods such as essential oils and herbicide application have shown reasonable success for controlling this weed. Therefore, this review aims to synthesise the identified and potentially useful approaches to control S. elaeagnifolium that have been recorded in the literature which deal with its biology, distribution and management. It also explores previous and current management techniques to ascertain the research gaps and knowledge required to assist in the effective and economically sustainable management of this invasive weed.

Marcussen, T., H. E. Ballard, J. Danihelka, A. R. Flores, M. V. Nicola, and J. M. Watson. 2022. A Revised Phylogenetic Classification for Viola (Violaceae). Plants 11: 2224. https://doi.org/10.3390/plants11172224

The genus Viola (Violaceae) is among the 40–50 largest genera among angiosperms, yet its taxonomy has not been revised for nearly a century. In the most recent revision, by Wilhelm Becker in 1925, the then-known 400 species were distributed among 14 sections and numerous unranked groups. Here, we provide an updated, comprehensive classification of the genus, based on data from phylogeny, morphology, chromosome counts, and ploidy, and based on modern principles of monophyly. The revision is presented as an annotated global checklist of accepted species of Viola, an updated multigene phylogenetic network and an ITS phylogeny with denser taxon sampling, a brief summary of the taxonomic changes from Becker’s classification and their justification, a morphological binary key to the accepted subgenera, sections and subsections, and an account of each infrageneric subdivision with justifications for delimitation and rank including a description, a list of apomorphies, molecular phylogenies where possible or relevant, a distribution map, and a list of included species. We distribute the 664 species accepted by us into 2 subgenera, 31 sections, and 20 subsections. We erect one new subgenus of Viola (subg. Neoandinium, a replacement name for the illegitimate subg. Andinium), six new sections (sect. Abyssinium, sect. Himalayum, sect. Melvio, sect. Nematocaulon, sect. Spathulidium, sect. Xanthidium), and seven new subsections (subsect. Australasiaticae, subsect. Bulbosae, subsect. Clausenianae, subsect. Cleistogamae, subsect. Dispares, subsect. Formosanae, subsect. Pseudorupestres). Evolution within the genus is discussed in light of biogeography, the fossil record, morphology, and particular traits. Viola is among very few temperate and widespread genera that originated in South America. The biggest identified knowledge gaps for Viola concern the South American taxa, for which basic knowledge from phylogeny, chromosome counts, and fossil data is virtually absent. Viola has also never been subject to comprehensive anatomical study. Studies into seed anatomy and morphology are required to understand the fossil record of the genus.

Testo, W. L., A. L. de Gasper, S. Molino, J. M. G. y Galán, A. Salino, V. A. de O. Dittrich, and E. B. Sessa. 2022. Deep vicariance and frequent transoceanic dispersal shape the evolutionary history of a globally distributed fern family. American Journal of Botany. https://doi.org/10.1002/ajb2.16062

Premise Historical biogeography of ferns is typically expected to be dominated by long-distance dispersal, due to their minuscule spores. However, few studies have inferred the historical biogeography of a large and widely distributed group of ferns to test this hypothesis. Our aims are to determine the extent to which long-distance dispersal vs. vicariance have shaped the history of the fern family Blechnaceae, to explore ecological correlates of dispersal and diversification, and to determine whether these patterns differ between the northern and southern hemispheres. Methods We used sequence data for three chloroplast loci to infer a time-calibrated phylogeny for 154 out of 265 species of Blechnaceae, including representatives of all genera in the family. This tree was used to conduct ancestral range reconstruction and stochastic character mapping, estimate diversification rates, and identify ecological correlates of diversification. Key results Blechnaceae originated in Eurasia and began diversifying in the late Cretaceous. A lineage comprising most extant diversity diversified principally in the austral Pacific region around the Paleocene-Eocene Thermal Maximum. Land connections that existed near the poles during periods of warm climates likely facilitated migration of several lineages, with subsequent climate-mediated vicariance shaping current distributions. Long-distance dispersal is frequent and asymmetrical, with New Zealand/Pacific Islands, Australia, and tropical America being major source areas. Conclusions Ancient vicariance and extensive long-distance dispersal have shaped the history of Blechnaceae in both the northern and southern hemispheres. The exceptional diversity in austral regions appears to reflect rapid speciation in these areas; mechanisms underlying this evolutionary success remain uncertain.

Amaral, D. T., I. A. S. Bonatelli, M. Romeiro-Brito, E. M. Moraes, and F. F. Franco. 2022. Spatial patterns of evolutionary diversity in Cactaceae show low ecological representation within protected areas. Biological Conservation 273: 109677. https://doi.org/10.1016/j.biocon.2022.109677

Mapping biodiversity patterns across taxa and environments is crucial to address the evolutionary and ecological dimensions of species distribution, suggesting areas of particular importance for conservation purposes. Within Cactaceae, spatial diversity patterns are poorly explored, as are the abiotic factors that may predict these patterns. We gathered geographic and genetic data from 921 cactus species by exploring both the occurrence and genetic databases, which are tightly associated with drylands, to evaluate diversity patterns, such as phylogenetic diversity and endemism, paleo-, neo-, and superendemism, and the environmental predictor variables of such patterns in a global analysis. Hotspot areas of cacti diversity are scattered along the Neotropical and Nearctic regions, mainly in the desertic portion of Mesoamerica, Caribbean Island, and the dry diagonal of South America. The geomorphological features of these regions may create a complexity of areas that work as locally buffered zones over time, which triggers local events of diversification and speciation. Desert and dryland/dry forest areas comprise paleo- and superendemism and may act as both museums and cradles of species, displaying great importance for conservation. Past climates, topography, soil features, and solar irradiance seem to be the main predictors of distinct endemism types. The hotspot areas that encompass a major part of the endemism cells are outside or poorly covered by formal protection units. The current legally protected areas are not able to conserve the evolutionary diversity of cacti. Given the rapid anthropogenic disturbance, efforts must be reinforced to monitor biodiversity and the environment and to define/plan current and new protected areas.

Quiroga, M. P., and C. P. Souto. 2022. Ecological niche modeling, niche overlap, and good old Rabinowitz’s rarities applied to the conservation of gymnosperms in a global biodiversity hotspot. Landscape Ecology. https://doi.org/10.1007/s10980-022-01502-z

Context Biodiversity hotspots harbor 77% of endemic plant species. Patagonian Temperate Forest (PTF) is a part of a biodiversity hotspot, but over the past centuries, has been over-exploited, fragmented and replaced with exotic species plantations, lately also threatened by climate change. Objectives Our aim is to better understand patterns of habitat suitability and niche overlap of nine endemic gymnosperm species, key elements of the PTF, complementing traditional approaches of biodiversity conservation. Methods Using R packages and 3016 occurrence data, we deployed ecological niche models (ENM) in MaxEnt via kuenm, and classified species according to Rabinowitz’s types of rarity. We then overlapped their niches calculating Schoener's D index, and considered types of rarity in a spatial ecological context. Finally, we overlay high species’ suitability and protected areas and detected conservation priorities using GapAnalysis. Results We generated simplified ENMs for nine Patagonian gymnosperms and found that most niches overlap, and only one species displayed a unique niche. Surprisingly, we found that three species have divergent suitability of habitats across the landscape and not related with previously published geographic structure of neutral genetic variation. We showed that the rarer a species is the smaller niche volume tend to have, that six out of nine studied species have high conservation priority, and that there are conservation gaps in the PTF. Conclusion Our approach showed that there are unprotected suitable areas for native key species at high risk in PTF. Suggesting that integrating habitat-suitability models of multiple species, types of rarity, and niche overlap, can be a handy tool to identify potential conservation areas in global biodiversity hotspots.

Ramirez-Villegas, J., C. K. Khoury, H. A. Achicanoy, M. V. Diaz, A. C. Mendez, C. C. Sosa, Z. Kehel, et al. 2022. State of ex situ conservation of landrace groups of 25 major crops. Nature Plants 8: 491–499. https://doi.org/10.1038/s41477-022-01144-8

Crop landraces have unique local agroecological and societal functions and offer important genetic resources for plant breeding. Recognition of the value of landrace diversity and concern about its erosion on farms have led to sustained efforts to establish ex situ collections worldwide. The degree to which these efforts have succeeded in conserving landraces has not been comprehensively assessed. Here we modelled the potential distributions of eco-geographically distinguishable groups of landraces of 25 cereal, pulse and starchy root/tuber/fruit crops within their geographic regions of diversity. We then analysed the extent to which these landrace groups are represented in genebank collections, using geographic and ecological coverage metrics as a proxy for genetic diversity. We find that ex situ conservation of landrace groups is currently moderately comprehensive on average, with substantial variation among crops; a mean of 63% ± 12.6% of distributions is currently represented in genebanks. Breadfruit, bananas and plantains, lentils, common beans, chickpeas, barley and bread wheat landrace groups are among the most fully represented, whereas the largest conservation gaps persist for pearl millet, yams, finger millet, groundnut, potatoes and peas. Geographic regions prioritized for further collection of landrace groups for ex situ conservation include South Asia, the Mediterranean and West Asia, Mesoamerica, sub-Saharan Africa, the Andean mountains of South America and Central to East Asia. With further progress to fill these gaps, a high degree of representation of landrace group diversity in genebanks is feasible globally, thus fulfilling international targets for their ex situ conservation. By analysing the state of representation of traditional varieties of 25 major crops in ex situ repositories, this study demonstrates conservation progress made over more than a half-century and identifies the gaps remaining to be filled.

Williams, C. J. R., D. J. Lunt, U. Salzmann, T. Reichgelt, G. N. Inglis, D. R. Greenwood, W. Chan, et al. 2022. African Hydroclimate During the Early Eocene From the DeepMIP Simulations. Paleoceanography and Paleoclimatology 37. https://doi.org/10.1029/2022pa004419

The early Eocene (∼56‐48 million years ago) is characterised by high CO2 estimates (1200‐2500 ppmv) and elevated global temperatures (∼10 to 16°C higher than modern). However, the response of the hydrological cycle during the early Eocene is poorly constrained, especially in regions with sparse data coverage (e.g. Africa). Here we present a study of African hydroclimate during the early Eocene, as simulated by an ensemble of state‐of‐the‐art climate models in the Deep‐time Model Intercomparison Project (DeepMIP). A comparison between the DeepMIP pre‐industrial simulations and modern observations suggests that model biases are model‐ and geographically dependent, however these biases are reduced in the model ensemble mean. A comparison between the Eocene simulations and the pre‐industrial suggests that there is no obvious wetting or drying trend as the CO2 increases. The results suggest that changes to the land sea mask (relative to modern) in the models may be responsible for the simulated increases in precipitation to the north of Eocene Africa. There is an increase in precipitation over equatorial and West Africa and associated drying over northern Africa as CO2 rises. There are also important dynamical changes, with evidence that anticyclonic low‐level circulation is replaced by increased south‐westerly flow at high CO2 levels. Lastly, a model‐data comparison using newly‐compiled quantitative climate estimates from palaeobotanical proxy data suggests a marginally better fit with the reconstructions at lower levels of CO2.

Reichgelt, T., D. R. Greenwood, S. Steinig, J. G. Conran, D. K. Hutchinson, D. J. Lunt, L. J. Scriven, and J. Zhu. 2022. Plant Proxy Evidence for High Rainfall and Productivity in the Eocene of Australia. Paleoceanography and Paleoclimatology 37. https://doi.org/10.1029/2022pa004418

During the early to middle Eocene, a mid‐to‐high latitudinal position and enhanced hydrological cycle in Australia would have contributed to a wetter and “greener” Australian continent where today arid to semi‐arid climates dominate. Here, we revisit 12 southern Australian plant megafossil sites from the early to middle Eocene to generate temperature, precipitation and seasonality paleoclimate estimates, net primary productivity (NPP) and vegetation type, based on paleobotanical proxies and compare to early Eocene global climate models. Temperature reconstructions are uniformly subtropical (mean annual, summer, and winter mean temperatures 19–21 °C, 25–27 °C and 14–16 °C, respectively), indicating that southern Australia was ∼5 °C warmer than today, despite a >20° poleward shift from its modern geographic location. Precipitation was less homogeneous than temperature, with mean annual precipitation of ∼60 cm over inland sites and >100 cm over coastal sites. Precipitation may have been seasonal with the driest month receiving 2–7× less than mean monthly precipitation. Proxy‐model comparison is favorable with an 1680 ppm CO2 concentration. However, individual proxy reconstructions can disagree with models as well as with each other. In particular, seasonality reconstructions have systemic offsets. NPP estimates were higher than modern, implying a more homogenously “green” southern Australia in the early to middle Eocene, when this part of Australia was at 48–64 °S, and larger carbon fluxes to and from the Australian biosphere. The most similar modern vegetation type is modern‐day eastern Australian subtropical forest, although distance from coast and latitude may have led to vegetation heterogeneity.

Sarker, U., Y.-P. Lin, S. Oba, Y. Yoshioka, and K. Hoshikawa. 2022. Prospects and potentials of underutilized leafy Amaranths as vegetable use for health-promotion. Plant Physiology and Biochemistry 182: 104–123. https://doi.org/10.1016/j.plaphy.2022.04.011

Climate change causes environmental variation worldwide, which is one of the most serious threats to global food security. In addition, more than 2 billion people in the world are reported to suffer from serious malnutrition, referred to as ‘hidden hunger.’ Dependence on only a few crops could lead to the loss of genetic diversity and high fragility of crop breeding in systems adapting to global scale climate change. The exploitation of underutilized species and genetic resources, referred to as orphan crops, could be a useful approach for resolving the issue of adaptability to environmental alteration, biodiversity preservation, and improvement of nutrient quality and quantity to ensure food security. Moreover, the use of these alternative crops will help to increase the human health benefits and the income of farmers in developing countries. In this review, we highlight the potential of orphan crops, especially amaranths, for use as vegetables and health-promoting nutritional components. This review highlights promising diversified sources of amaranth germplasms, their tolerance to abiotic stresses, and their nutritional, phytochemical, and antioxidant values for vegetable purposes. Betalains (betacyanins and betaxanthins), unique antioxidant components in amaranth vegetables, are also highlighted regarding their chemodiversity across amaranth germplasms and their stability and degradation. In addition, we discuss the physiological functions, antioxidant, antilipidemic, anticancer, and antimicrobial activities, as well as the biosynthesis pathway, molecular, biochemical, genetics, and genomic mechanisms of betalains in detail.

Sluiter, I. R. K., G. R. Holdgate, T. Reichgelt, D. R. Greenwood, A. P. Kershaw, and N. L. Schultz. 2022. A new perspective on Late Eocene and Oligocene vegetation and paleoclimates of South-eastern Australia. Palaeogeography, Palaeoclimatology, Palaeoecology 596: 110985. https://doi.org/10.1016/j.palaeo.2022.110985

We present a composite terrestrial pollen record of latest Eocene through Oligocene (35.5–23 Ma) vegetation and climate change from the Gippsland Basin of south-eastern Australia. Climates were overwhelmingly mesothermic through this time period, with mean annual temperature (MAT) varying between 13 and 18 °C, with an average of 16 °C. We provide evidence to support a cooling trend through the Eocene–Oligocene Transition (EOT), but also identify three subsequent warming cycles through the Oligocene, leading to more seasonal climates at the termination of the Epoch. One of the warming episodes in the Early Oligocene appears to have also occurred at two other southern hemisphere sites at the Drake Passage as well as off eastern Tasmania, based on recent research. Similarities with sea surface temperature records from modern high southern latitudes which also record similar cycles of warming and cooling, are presented and discussed. Annual precipitation varied between 1200 and 1700 mm/yr, with an average of 1470 mm/yr through the sequence. Notwithstanding the extinction of Nothofagus sg. Brassospora from Australia and some now microthermic humid restricted Podocarpaceae conifer taxa, the rainforest vegetation of lowland south-eastern Australia is reconstructed to have been similar to present day Australian Evergreen Notophyll Vine Forests existing under the sub-tropical Köppen-Geiger climate class Cfa (humid subtropical) for most of the sequence. Short periods of cooler climates, such as occurred through the EOT when MAT was ~ 13 °C, may have supported vegetation similar to modern day Evergreen Microphyll Fern Forest. Of potentially greater significance, however, was a warm period in the Early to early Late Oligocene (32–26 Ma) when MAT was 17–18 °C, accompanied by small but important increases in Araucariaceae pollen. At this time, Araucarian Notophyll/Microphyll Vine Forest likely occurred regionally.