Science Enabled by Specimen Data

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.

Heo, N., M. V. Lomolino, J. E. Watkins, S. Yun, J. Weber-Townsend, and D. D. Fernando. 2022. Evolutionary history of the Asplenium scolopendrium complex (Aspleniaceae), a relictual fern with a northern pan-temperate disjunct distribution. Biological Journal of the Linnean Society. https://doi.org/10.1093/biolinnean/blac080

Abstract Asplenium scolopendrium is distributed in northern temperate forests with many global biogeographic disjunctions. The species complex of A. scolopendrium has been generated by spatial segregation coupled with divergent evolution. We elucidated the biogeographic history of the A. scolopendrium complex by exploring its origin, dispersal and evolution, thus providing insights into the evolutionary history of the Tertiary floras with northern pan-temperate disjunct distributions. The results revealed that all infraspecific taxa descended from a widely distributed common ancestor in the Northern Hemisphere. This pan-temperate ancestral population formed by unidirectional westward dispersal from European origins primarily during the Early Eocene when the Earth’s climate was much warmer than today. The splitting of European, American and East Asian lineages occurred during the Early Miocene due to geo-climatic vicariances. Polyploidy events in the American ancestral populations created additional reproductive barriers. The star-shaped haplotypes in each continent indicated that local disjunctions also led to derived genotypes with potential to diverge into different taxa. This intracontinental lineage splitting is likely related to latitudinal range shift and habitat fragmentation caused by glacial cycles and climate change during the Pleistocene. The evolutionary history of the A. scolopendrium complex supported the Boreotropical hypothesis exhibiting range expansion during the Early Eocene Climatic Optimum.

Rusconi, O., O. Broennimann, Y. Storrer, R. Le Bayon, A. Guisan, and S. Rasmann. 2022. Detecting preservation and reintroduction sites for endangered plant species using a two‐step modeling and field approach. Conservation Science and Practice. https://doi.org/10.1111/csp2.12800

To withstand the surge of species loss worldwide, (re)introduction of endangered plant species has become an increasingly common technique in conservation biology. Successful (re)introduction plans, however, require identifying sites that provide the optimal ecological conditions for the target species to thrive. In this study, we propose a two‐step approach to identify appropriate (re)introduction sites. The first step involves modeling the niche and distribution of the species with bioclimatic and topographical predictors, both at continental and at national scales. The second step consists of refining these bioclimatic predictions by analyzing stationary ecological parameters, such as soil conditions, and relating them to population‐level fitness values. We demonstrate this methodology using Swiss populations of the lady's slipper orchid (Cypripedium calceolus L., Orchidaceae), for which conservation plans have existed for years but have generally been unfruitful. Our workflow identified sites for future (re)introductions based on the species requirements for mid‐to‐sunny light conditions and specific soil physico‐chemical properties, such as basic to neutral pH and low soil organic matter content. Our findings show that by combining wide‐scale bioclimatic modeling with fine scale field measurements it is possible to carefully identify the ecological requirements of a target species for successful (re)introductions.

Lu, L.-L., B.-H. Jiao, F. Qin, G. Xie, K.-Q. Lu, J.-F. Li, B. Sun, et al. 2022. Artemisia pollen dataset for exploring the potential ecological indicators in deep time. Earth System Science Data 14: 3961–3995. https://doi.org/10.5194/essd-14-3961-2022

Abstract. Artemisia, along with Chenopodiaceae, is the dominant component growing in the desert and dry grassland of the Northern Hemisphere. Artemisia pollen with its high productivity, wide distribution, and easy identification is usually regarded as an eco-indicator for assessing aridity and distinguishing grassland from desert vegetation in terms of the pollen relative abundance ratio of Chenopodiaceae/Artemisia (C/A). Nevertheless, divergent opinions on the degree of aridity evaluated by Artemisia pollen have been circulating in the palynological community for a long time. To solve the confusion, we first selected 36 species from nine clades and three outgroups of Artemisia based on the phylogenetic framework, which attempts to cover the maximum range of pollen morphological variation. Then, sampling, experiments, photography, and measurements were taken using standard methods. Here, we present pollen datasets containing 4018 original pollen photographs, 9360 pollen morphological trait measurements, information on 30 858 source plant occurrences, and corresponding environmental factors. Hierarchical cluster analysis on pollen morphological traits was carried out to subdivide Artemisia pollen into three types. When plotting the three pollen types of Artemisia onto the global terrestrial biomes, different pollen types of Artemisia were found to have different habitat ranges. These findings change the traditional concept of Artemisia being restricted to arid and semi-arid environments. The data framework that we designed is open and expandable for new pollen data of Artemisia worldwide. In the future, linking pollen morphology with habitat via these pollen datasets will create additional knowledge that will increase the resolution of the ecological environment in the geological past. The Artemisia pollen datasets are freely available at Zenodo (https://doi.org/10.5281/zenodo.6900308; Lu et al., 2022).

Pereira, R. F. P., J. Rocha, P. Nunes, T. Fernandes, A. P. Ravishankar, R. Cruz, M. Fernandes, et al. 2022. Vicariance Between Cercis siliquastrum L. and Ceratonia siliqua L. Unveiled by the Physical–Chemical Properties of the Leaves’ Epicuticular Waxes. Frontiers in Plant Science 13. https://doi.org/10.3389/fpls.2022.890647

Classically, vicariant phenomena have been essentially identified on the basis of biogeographical and ecological data. Here, we report unequivocal evidences that demonstrate that a physical–chemical characterization of the epicuticular waxes of the surface of plant leaves represents a very powerful strategy to get rich insight into vicariant events. We found vicariant similarity between Cercis siliquastrum L. (family Fabaceae, subfamily Cercidoideae) and Ceratonia siliqua L. (family Fabaceae, subfamily Caesalpinoideae). Both taxa converge in the Mediterranean basin (C. siliquastrum on the north and C. siliqua across the south), in similar habitats (sclerophyll communities of maquis) and climatic profiles. These species are the current representation of their subfamilies in the Mediterranean basin, where they overlap. Because of this biogeographic and ecological similarity, the environmental pattern of both taxa was found to be very significant. The physical–chemical analysis performed on the epicuticular waxes of C. siliquastrum and C. siliqua leaves provided relevant data that confirm the functional proximity between them. A striking resemblance was found in the epicuticular waxes of the abaxial surfaces of C. siliquastrum and C. siliqua leaves in terms of the dominant chemical compounds (1-triacontanol (C30) and 1-octacosanol (C28), respectively), morphology (intricate network of randomly organized nanometer-thick and micrometer-long plates), wettability (superhydrophobic character, with water contact angle values of 167.5 ± 0.5° and 162 ± 3°, respectively), and optical properties (in both species the light reflectance/absorptance of the abaxial surface is significantly higher/lower than that of the adaxial surface, but the overall trend in reflectance is qualitatively similar). These results enable us to include for the first time C. siliqua in the vicariant process exhibited by C. canadensis L., C. griffithii L., and C. siliquastrum.

Pérez, G., M. Vilà, and B. Gallardo. 2022. Potential impact of four invasive alien plants on the provision of ecosystem services in Europe under present and future climatic scenarios. Ecosystem Services 56: 101459. https://doi.org/10.1016/j.ecoser.2022.101459

Invasive alien species (IAS) are one of the main threats to biodiversity conservation, with significant socio-economic and ecological impacts as they disrupt ecosystem services and compromise human well-being. Global change may exacerbate the impacts of IAS, since rising temperatures and human activities favour their introduction and range expansion. Therefore, anticipating the impacts of biological invasions is crucial to support decision-making for their management. In this work, the potential impacts of four invasive alien plant species: Ailanthus altissima, Baccharis halimifolia, Impatiens glandulifera and Pueraria montana, on the provision of three ecosystem services in Europe were evaluated under current and future climate change scenarios. Using a risk analysis protocol, we determined that the most affected services are food provisioning, soil erosion regulation and the maintenance of biological diversity. To evaluate future impacts, species distribution models were calibrated using bioclimatic, environmental and human impact variables. We found that most of continental Europe is suitable for the establishment of A. altissima, B. halimifolia and I. glandulifera, while the potential distribution of P. montana is more limited. Models anticipate a shift in the distribution range for the species towards the north and east of Europe under future scenarios. Bivariate analysis allowed the identification of trends for future impacts in ecosystem services by simultaneously visualising the potential distribution of invasive species and the provision of ecosystem services. Our models project an increase in critical and high impact areas on the analysed ecosystem services, with Western Europe and the British Isles as the most affected regions. In comparison, lower impacts are projected for the Mediterranean region, likely as a consequence of the northwards expansion of invaders. Measures need to be taken to mitigate the expansion and impact of invasive species as our work shows that it can jeopardise the provision of three key services in Europe.

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.

Camacho, F., and G. Peyre. 2022. Red List and Vulnerability Assessment of the Páramo Vascular Flora in the Nevados Natural National Park (Colombia). Tropical Conservation Science 15: 194008292210869. https://doi.org/10.1177/19400829221086958

Background and research aims. The Andean páramo is renowned for its unique biodiversity and sensitivity to environmental threats. However, vulnerability assessments remain scarce, which hinders our capacity to prioritize and apply efficient conservation measures. To this end, we established the Red List of the páramo vascular flora from the Nevados National Natural Park and proposed conservation strategies for its threatened species. Methods. We performed International Union for Conservation of Nature (IUCN) Red List assessments by evaluating Criterion B, including sub-criteria B1–Extent of Occurrence and B2–Area of Occupancy, and using a systematic geographic-ecological approach for conditions a (Location analysis) and b (Continuing decline). We then executed a Conservation Gap Analysis to prioritize species for in- situ and/or ex-situ conservation. Results. Summing our 233 evaluated species with previous assessments, we completed the Red List of 262 páramo species and encountered 3% Threatened (7 VU, one EN), 44% Not Threatened (65 LC, 50 NT), and 53% Data Deficient. We acknowledged Lupinus ruizensis as Endangered and Aequatorium jamesonii, Carex jamesonii, Elaphoglossum cuspidatum, Miconia latifolia, Miconia alborosea, Pentacalia gelida, and Themistoclesia mucronata as Vulnerable. Conclusion. The eight threatened species should be included as target species in the PNN Nevados management plan 2023–2028 and regarded as national conservation priorities. Implications for Conservation. We recommend in-situ conservation for Medium-Priority species A. jamesonii, E. cuspidatum, and T. mucronata with thorough monitoring, paired with sub-population transfers for High-Priority species C. jamesonii. For the endemic L. ruizensis and P. gelida, we suggest combined in-situ/ex-situ strategies taking advantage of national germoplasm collections, like the seed bank of the Bogotá Botanical Garden José Celestino Mutis.

Pirie, M. D., R. Blackhall‐Miles, G. Bourke, D. Crowley, I. Ebrahim, F. Forest, M. Knaack, et al. 2022. Preventing species extinctions: A global conservation consortium for Erica. PLANTS, PEOPLE, PLANET 4: 335–344. https://doi.org/10.1002/ppp3.10266

Societal Impact Statement Human-caused habitat destruction and transformation is resulting in a cascade of impacts to biological diversity, of which arguably the most fundamental is species extinctions. The Global Conservation Consortia (GCC) are a means to pool efforts and expertise across national boundaries and between disciplines in the attempt to prevent such losses in focal plant groups. GCC Erica coordinates an international response to extinction threats in one such group, the heaths, or heathers, of which hundreds of species are found only in South Africa's spectacularly diverse Cape Floristic Region. Summary Effectively combating the biodiversity crisis requires coordinated conservation efforts. Botanic Gardens Conservation International (BGCI) and numerous partners have established Global Conservation Consortia (GCC) to collaboratively develop and implement comprehensive conservation strategies for priority threatened plant groups. Through these networks, institutions with specialised collections and staff can leverage ongoing work to optimise impact for threatened plant species. The genus Erica poses a challenge similar in scale to that of the largest other GCC group, Rhododendron, but almost 700 of the around 800 known species of Erica are concentrated in a single biodiversity hotspot, the Cape Floristic Region (CFR) of South Africa. Many species are known to be threatened, suffering the immediate impacts of habitat destruction, invasive species, changes in natural fire regimes and climate change. Efforts to counter these threats face general challenges: disproportionate burden of in situ conservation falling on a minority of the community, limited knowledge of species-rich groups, shortfalls in assessing and monitoring threat, lack of resources for in situ and limitations of knowledge for ex situ conservation efforts and in communicating the value of biological diversity to a public who may never encounter it in the wild. GCC Erica brings together the world's Erica experts, conservationists and the botanical community, including botanic gardens, seed banks and organisations in Africa, Madagascar, Europe, the United States, Australia and beyond. We are collaboratively pooling our unique sets of skills and resources to address these challenges in working groups for conservation prioritisation, conservation in situ, horticulture, seed banking, systematic research and outreach.

Bywater‐Reyes, S., R. M. Diehl, A. C. Wilcox, J. C. Stella, and L. Kui. 2022. A Green New Balance: Interactions among riparian vegetation plant traits and morphodynamics in alluvial rivers. Earth Surface Processes and Landforms 47: 2410–2436. https://doi.org/10.1002/esp.5385

The strength of interactions between plants and river processes is mediated by plant traits and fluvial conditions, including above‐ground biomass, stem density and flexibility, channel and bed material properties, and flow and sediment regimes. In many rivers, concurrent changes in 1) the composition of riparian vegetation communities as a result of exotic species invasion and 2) shifts in hydrology have altered physical and ecological conditions in a manner that has been mediated by feedbacks between vegetation and morphodynamic processes. We review how Tamarix, which has invaded many U.S. Southwest waterways, and Populus species, woody pioneer trees that are native to the region, differentially affect hydraulics, sediment transport, and river morphology. We draw on flume, field, and modeling approaches spanning the individual seedling to river‐corridor scales. In a flume study, we found differences in the crown morphology, stem density, and flexibility of Tamarix compared to Populus influenced near‐bed flow velocities in a manner that favored aggradation associated with Tamarix. Similarly, at the patch and corridor scales, observations confirmed increased aggradation with increased vegetation density. Furthermore, long‐term channel adjustments were different for Tamarix‐ versus Populus‐dominated reaches, with faster and greater geomorphic adjustments for Tamarix. Collectively, our studies show how plant‐trait differences between Tamarix and Populus, from individual seedlings to larger spatial and temporal scales, influence the co‐adjustment of rivers and riparian plant communities. These findings provide a basis for predicting changes in alluvial riverine systems which we conceptualize as a Green New Balance model that considers how channels may adjust to changes in plant traits and community structure in additional to alterations in flow and sediment supply. We offer suggestions regarding how the Green New Balance can be used in management and invasive species management.