Science Enabled by Specimen Data

Smith, A. B., S. J. Murphy, D. Henderson, and K. D. Erickson. 2023. Including imprecisely georeferenced specimens improves accuracy of species distribution models and estimates of niche breadth. Global Ecology and Biogeography. https://doi.org/10.1111/geb.13628

Aim Museum and herbarium specimen records are frequently used to assess the conservation status of species and their responses to climate change. Typically, occurrences with imprecise geolocality information are discarded because they cannot be matched confidently to environmental conditions and are thus expected to increase uncertainty in downstream analyses. However, using only precisely georeferenced records risks undersampling of the environmental and geographical distributions of species. We present two related methods to allow the use of imprecisely georeferenced occurrences in biogeographical analysis. Innovation Our two procedures assign imprecise records to the (1) locations or (2) climates that are closest to the geographical or environmental centroid of the precise records of a species. For virtual species, including imprecise records alongside precise records improved the accuracy of ecological niche models projected to the present and the future, especially for species with c. 20 or fewer precise occurrences. Using only precise records underestimated loss of suitable habitat and overestimated the amount of suitable habitat in both the present and the future. Including imprecise records also improves estimates of niche breadth and extent of occurrence. An analysis of 44 species of North American Asclepias (Apocynaceae) yielded similar results. Main conclusions Existing studies examining the effects of spatial imprecision typically compare outcomes based on precise records against the same records with spatial error added to them. However, in real-world cases, analysts possess a mix of precise and imprecise records and must decide whether to retain or discard the latter. Discarding imprecise records can undersample the geographical and environmental distributions of species and lead to mis-estimation of responses to past and future climate change. Our method, for which we provide a software implementation in the enmSdmX package for R, is simple to use and can help leverage the large number of specimen records that are typically deemed “unusable” because of spatial imprecision in their geolocation.

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. https://doi.org/10.1371/journal.pone.0275744

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.

Tackett, M., C. Berg, T. Simmonds, O. Lopez, J. Brown, R. Ruggiero, and J. Weber. 2022. Breeding system and geospatial variation shape the population genetics of Triodanis perfoliata. Ecology and Evolution 12. https://doi.org/10.1002/ece3.9382

Both intrinsic and extrinsic forces work together to shape connectivity and genetic variation in populations across the landscape. Here we explored how geography, breeding system traits, and environmental factors influence the population genetic patterns of Triodanis perfoliata, a widespread mix‐mating annual plant in the contiguous US. By integrating population genomic data with spatial analyses and modeling the relationship between a breeding system and genetic diversity, we illustrate the complex ways in which these forces shape genetic variation. Specifically, we used 4705 single nucleotide polymorphisms to assess genetic diversity, structure, and evolutionary history among 18 populations. Populations with more obligately selfing flowers harbored less genetic diversity (π: R2 = .63, p = .01, n = 9 populations), and we found significant population structuring (FST = 0.48). Both geographic isolation and environmental factors played significant roles in predicting the observed genetic diversity: we found that corridors of suitable environments appear to facilitate gene flow between populations, and that environmental resistance is correlated with increased genetic distance between populations. Last, we integrated our genetic results with species distribution modeling to assess likely patterns of connectivity among our study populations. Our landscape and evolutionary genetic results suggest that T. perfoliata experienced a complex demographic and evolutionary history, particularly in the center of its distribution. As such, there is no singular mechanism driving this species' evolution. Together, our analyses support the hypothesis that the breeding system, geography, and environmental variables shape the patterns of diversity and connectivity of T. perfoliata in the US.

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.

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. https://doi.org/10.1111/mec.16715

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. 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.

Ward, S. F., E. G. Brockerhoff, R. M. Turner, T. Yamanaka, L. Marini, S. Fei, and A. M. Liebhold. 2022. Prevalence and drivers of a tree-killing bark beetle, Ips typographus (Coleoptera, Scolytinae), in international invasion pathways into the USA. Journal of Pest Science. https://doi.org/10.1007/s10340-022-01559-4

The unintentional transport of insects beyond their native ranges has greatly increased with globalization over the past century, leading to higher propagule pressure in non-native ranges of many species. Knowledge about the prevalence of a species in international invasion pathways is important for predicting invasions and taking appropriate biosecurity measures. We investigated the spatiotemporal patterns and drivers of interceptions—detections of at least one individual with imported goods that potentially serve as a proxy for arrival rates—for a tree-killing bark beetle, the European spruce bark beetle ( Ips typographus L.; Coleoptera: Curculionidae: Scolytinae), in the USA from 1914 to 2008. Across the study period, there were 505 interceptions of I. typographus with shipments originating from > 25 countries at ports in 22 US states. Interceptions first occurred in 1938, peaked at 33 and 25 in 1984 and 1996, respectively, and declined after the mid-1990s. Interceptions of I. typographus did not have a statistically detectable relationship with outbreak levels in the native range, were inversely related to annual import volume (an artifact likely driven by changes in inspection policies), and were more frequent during the winter. Thus, while interceptions of I. typographus are challenging to predict, we found evidence that (i) biosecurity practices against this beetle could be increased during winter but not in response to outbreaks in source regions and (ii) the overall abundance of this beetle in invasion pathways has recently decreased, probably because strengthened phytosanitary protocols have reduced contamination levels and/or decreased the perceived need for inspections.

Ding, W., H. Li, and J. Wen. 2022. Response of the invasive plant Ailanthus altissima (Mill.) Swingle and its two important natural enemies (Eucryptorrhynchus scrobiculatus (Motschulsky) and E. brandti (Harold)) to climate change. Ecological Indicators 143: 109408. https://doi.org/10.1016/j.ecolind.2022.109408

Invasive species Tree-of-heaven (Ailanthus altissima (Mill.) Swingle) caused serious damage on ecosystem, economy, and public health in the United States and Europe. Two weevils (Eucryptorrhynchus scrobiculatus (Motschulsky) and E. brandti (Harold)) are considered to be potential enemies for biological control. In this study, we integrated potential distribution, bioclimatic suitability shifts and niche overlap to assess the global invasion risk of A. altissima under climate change and the possibility of E. scrobiculatus and E. brandti as potential natural enemies. Suitable area of A. altissima will be expanded under SSP 585. The future climate conditions do not seem to be suitable for the growth of E. scrobiculatus, but are conducive to E. brandti. We found that the suitable area of A. altissima would spread to the south and north, while two weevils spread mainly to the central and northern parts in the United States. The mean temperature of the coldest quarter (BIO11, 43.3%) was the most important bioclimatic variable in the forecasts for A. altissima and E. brandti. The wettest quarter’s mean temperature (BIO8, 35.7%) had the strongest influence on predictions for E. scrobiculatus. Our findings can provide a theoretical basis for preventing A. altissima from continuing to invade other areas. At the same time, it explained one reason why E. scrobiculatus and E. brandti could not effectively control A. altissima, and evaluated its feasibility as a potential natural enemy under future climatic conditions.

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).

Contreras-Medina, R., M. Santiago-Alvarado, D. Espinosa, G. Rivas, and I. Luna-Vega. 2022. Distributional patterns and conservation of the genus Habromys (Rodentia: Cricetidae) in Mesoamerica. Studies on Neotropical Fauna and Environment: 1–17. https://doi.org/10.1080/01650521.2022.2085071

We analyzed the geographical distribution of Habromys species based on distributional data from museum specimens, web databases, and literature. We recorded species-presence data of each species in 0.5° × 0.5° grid cells and biogeographic provinces in Mexico and Central America. We analyzed the association between vegetation types and land use. We carried out species distribution models of most species of Habromys and those tree species frequently harboring these mice, finding a high distributional congruence among mice and trees. Species of Habromys occur throughout the montane systems of Mexico and northern Central America, so they can be considered characteristic elements of the Neotropical montane cloud forests. All species of the genus occur in Mexico, whereas Guatemala and El Salvador have only one species. Although all species of Habromys are highly restricted and considered rare species, only one (H. simulatus) is currently protected by Mexican laws. We assigned two species to a high and four to the critical conservation risk. Habromys species contribute to the recognition of Mesoamerica as a biodiversity hotspot.