Science Enabled by Specimen Data

Pan, Y., J. García-Girón, and L. L. Iversen. 2023. Global change and plant-ecosystem functioning in freshwaters. Trends in Plant Science.

Freshwater ecosystems are of worldwide importance for maintaining biodiversity and sustaining the provision of a myriad of ecosystem services to modern societies. Plants, one of the most important components of these ecosystems, are key to water nutrient removal, carbon storage, and food provision. Understanding how the functional connection between freshwater plants and ecosystems is affected by global change will be key to our ability to predict future changes in freshwater systems. Here, we synthesize global plant responses, adaptations, and feedbacks to present-day and future freshwater environments through trait-based approaches, from single individuals to entire communities. We outline the transdisciplinary knowledge benchmarks needed to further understand freshwater plant biodiversity and the fundamental services they provide.

Ripley, B. S., S. L. Raubenheimer, L. Perumal, M. Anderson, E. Mostert, B. S. Kgope, G. F. Midgley, and K. J. Simpson. 2022. CO 2 ‐fertilisation enhances resilience to browsing in the recruitment phase of an encroaching savanna tree. Functional Ecology.

CO2‐fertilisation is implicated in the widespread and significant woody encroachment of savannas due to CO2‐stimulated increases in belowground reserves that enhance sapling regrowth after fire. However, the effect of CO2 concentration ([CO2]) on tree responses to the other major disturbance in savannas, herbivory, is poorly understood. Herbivory‐responses cannot be predicted from fire‐responses, as herbivore effects occur earlier during establishment and are moderated by plant palatability and defence rather than belowground carbon accumulation.

Kroonen, G., A. Jakob, A. I. Palmér, P. van Sluis, and A. Wigman. 2022. Indo-European cereal terminology suggests a Northwest Pontic homeland for the core Indo-European languages S. Wichmann [ed.],. PLOS ONE 17: e0275744.

Questions on the timing and the center of the Indo-European language dispersal are central to debates on the formation of the European and Asian linguistic landscapes and are deeply intertwined with questions on the archaeology and population history of these continents. Recent palaeogenomic studies support scenarios in which the core Indo-European languages spread with the expansion of Early Bronze Age Yamnaya herders that originally inhabited the East European steppes. Questions on the Yamnaya and Pre-Yamnaya locations of the language community that ultimately gave rise to the Indo-European language family are heavily dependent on linguistic reconstruction of the subsistence of Proto-Indo-European speakers. A central question, therefore, is how important the role of agriculture was among the speakers of this protolanguage. In this study, we perform a qualitative etymological analysis of all previously postulated Proto-Indo-European terminology related to cereal cultivation and cereal processing. On the basis of the evolution of the subsistence strategies of consecutive stages of the protolanguage, we find that one or perhaps two cereal terms can be reconstructed for the basal Indo-European stage, also known as Indo-Anatolian, but that core Indo-European, here also including Tocharian, acquired a more elaborate set of terms. Thus, we linguistically document an important economic shift from a mostly non-agricultural to a mixed agro-pastoral economy between the basal and core Indo-European speech communities. It follows that the early, eastern Yamnaya of the Don-Volga steppe, with its lack of evidence for agricultural practices, does not offer a perfect archaeological proxy for the core Indo-European language community and that this stage of the language family more likely reflects a mixed subsistence as proposed for western Yamnaya groups around or to the west of the Dnieper River.

Reichgelt, T., W. G. Lee, and D. E. Lee. 2022. The extinction of Miocene broad-leaved deciduous Nothofagaceae and loss of seasonal forest biomes in New Zealand. Review of Palaeobotany and Palynology: 104779.

Quantitative leaf mass per area reconstructions and prevalence of plicate vernation in broad-leaved Nothofagaceae fossils reveal that deciduousness was common in the middle to late Miocene of New Zealand. This functional type was subsequently lost, as modern-day New Zealand Nothofagaceae have small leaves that live for at least a year. Moreover, fully deciduous trees across all plant families are rare in the current New Zealand flora. Based on modern-day distribution in the Southern Hemisphere, broad-leaved deciduous Nothofagaceae occupy regions with consistently large seasonal differences in precipitation and cloud cover, relative to other functional types in the family (evergreen, small-leaved). Specifically, broad-leaved deciduous Nothofagaceae are in leaf in summer when cloud cover and precipitation are low, but are leafless in winter when cloud cover and precipitation is high. Notably, the seasonal difference in precipitation and cloud cover are more important in explaining deciduousness in Nothofagaceae than winter temperatures. Therefore, potential summer photosynthetic gains likely determine deciduousness in Nothofagaceae. Miocene palaeoclimate reconstructions reveal that New Zealand broad-leaved deciduous Nothofagaceae also thrived in a climate with larger seasonal precipitation differences than today, in an overall warmer climate. We suggest that deciduous Nothofagaceae in the New Zealand flora went extinct as the global climate cooled and summer photosynthetic gains diminished, as summers became progressively rainier and cloudier, favoring an evergreen habit.

Aguirre‐Liguori, J. A., A. Morales‐Cruz, and B. S. Gaut. 2022. Evaluating the persistence and utility of five wild Vitis species in the context of climate change. Molecular Ecology.

Crop wild relatives (CWRs) have the capacity to contribute novel traits to agriculture. Given climate change, these contributions may be especially vital for the persistence of perennial crops, because perennials are often clonally propagated and consequently do not evolve rapidly. By studying the landscape genomics of samples from five Vitis CWRs (V. arizonica, V. mustangensis, V. riparia, V. berlandieri and V. girdiana) in the context of projected climate change, we addressed two goals. The first was to assess the relative potential of different CWR accessions to persist in the face of climate change. By integrating species distribution models with adaptive genetic variation, additional genetic features such as genomic load and a phenotype (resistance to Pierce’s Disease), we predicted that accessions from one species (V. mustangensis) are particularly well‐suited to persist in future climates. The second goal was to identify which CWR accessions may contribute to bioclimatic adaptation for grapevine (V. vinifera) cultivation. To do so, we evaluated whether CWR accessions have the allelic capacity to persist if moved to locations where grapevines (V. vinifera) are cultivated in the United States. We identified six candidates from V. mustangensis and hypothesized that they may prove useful for contributing alleles that can mitigate climate impacts on viticulture. By identifying candidate germplasm, this work takes a conceptual step toward assessing the genomic and bioclimatic characteristics of CWRs.

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.

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.

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.

Clark, R. P., K.-W. Jiang, and E. Gagnon. 2022. Reinstatement of Ticanto (Leguminosae-Caesalpinioideae) – the final piece in the Caesalpinia group puzzle. PhytoKeys 205: 59–98.

A recent molecular phylogenetic analysis of the Caesalpinia group demonstrated that it comprises 26 genera, but the recognition of a putative 27th genus, Ticanto, remained in doubt. This study presents a phylogenetic analysis of ITS and five plastid loci revealing a robustly supported monophyletic group representing the Ticanto clade, sister to the morphologically distinct genus Pterolobium. Based upon this evidence, along with a morphological evaluation, the genus Ticanto is here reinstated. Descriptions are provided for all nine species of Ticanto, together with a key to the species, maps, and colour photographs. Nine new combinations are made: Ticantocaesia (Hand.-Mazz.) R. Clark & Gagnon, T.crista (L.) R. Clark & Gagnon, T.elliptifolia (S. J. Li, Z. Y. Chen & D. X. Zhang) R. Clark & Gagnon, T.magnifoliolata (Metcalf) R. Clark & Gagnon, T.rhombifolia R. Clark & Gagnon, T.sinensis (Hemsl.) R. Clark & Gagnon, T.szechuenensis (Craib) R. Clark & Gagnon, T.vernalis (Champion ex Benth.) R. Clark & Gagnon and T.yunnanensis (S. J. Li, D. X. Zhang & Z.Y. Chen) R. Clark & Gagnon. The final major question in the delimitation of segregate genera from within Caesalpiniasensu lato and the Caesalpinia group is thus resolved.

Hidalgo-Triana, N., F. Casimiro-Soriguer Solanas, A. Solakis Tena, A. V. Pérez-Latorre, and J. García-Sánchez. 2022. Melinis repens (Willd.) Zizka subsp. repens (Poaceae) in Europe: distribution, ecology and potential invasion. Botany Letters 169: 390–399.

Melinis repens subsp. repens is an annual herb native to Africa and southwestern Asia. In 2008, this species was detected growing in road verges and showing a reduced occupancy area of 6 km2 in a natural area of the southern Iberian Peninsula in the province of Malaga (Andalusia, Spain). The rest of the existing European records of this species comes from the Czech Republic, the Italian Peninsula, and Great Britain and can be considered casual. Furthermore, this species has become naturalised in Sardinia. The aim of this work is to study the invasion status, habitats, potential impacts, invasive behaviour, and pathways of introduction of Melinis repens subsp. repens in the southern Iberian Peninsula (Spain) to contribute to the control of this species. This species was most probably introduced into Europe for ornamental, fodder, or slope stabilization purposes. Our field work revealed this species has become naturalised in several habitats of Malaga and Granada provinces (Andalusia) occupying an area of 263 km2 in 2021. It behaves as a pioneer species that colonizes disturbed road margins and occurs in the same habitat as Cenchrus setaceus. Melinis repens subsp. repens can become dominant in natural EUNIS habitats and can also occupy cultivated areas. Because of the high occupancy area detected, and because the species has been assigned to the European Union List of Invasive Alien Plants based on the EPPO prioritization process, this plant should be considered the object of a control programme and its use should be legally prohibited in Spain, and more largely in European Mediterranean areas.

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.

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.