William Alfred Weber

Island ecosystems have significant conservation value owing to their higher endemic biotas. Moreover, studies of regional communities that compare differences in species composition (species dissimilarity) among islands and the mainland suggest that community assembly on islands is different from that on the mainland. However, the uniqueness of island biotic assembly has been little studied at the global scale, nor have phylogenetic information or alien species been considered in these patterns. We evaluate taxonomic and phylogenetic change from one community to the next, focusing on differences in species composition between mainland-mainland (M-M) pairs compared to differences between mainland-island pairs (M-I) and between island-island pairs (I-I), using herpetofauna on islands and adjacent mainland areas worldwide. Our analyses detect greater taxonomic and phylogenetic dissimilarity for M-I and I-I comparisons than predicted by M-M model, indicating different island herpetofauna assembly patterns compared with mainland counterparts across the world. However, this higher M-I dissimilarity has been significantly decreased after considering alien species. Our results provide global evidence on the importance of island biodiversity conservation from the aspect of both the taxonomic and phylogenetic uniqueness of island biotic assembly.

AbstractInvasive alien plants cause severe global problems; therefore, determining the factors that lead to the success or failure of invasion is a critical question in the field of invasion ecology. In this study, we aimed to determine the factors underlying differences in the distribution range of alien plants in Japan by investigating why Loliummultiflorum thrives in a wide range of habitats while L.rigidum is mainly distributed on sandy beaches. We initially evaluated environmental niche suitability through species distribution modelling and subsequently examined whether species traits influence the differences in range expansion between the two species. We used MaxEnt modelling to identify potential environmental niches for both species. The analysis revealed that L.rigidum was considerably less suited to the Japanese climate compared to L.multiflorum, with high summer precipitation in Japan identified as one of the climatic factors limiting the distribution of L.rigidum. Given that these winter annual plants remain dormant as seeds during summer, in subsequent experiments, we buried seeds in paddy field soil and sandy beach sand during summer and evaluated their survival rate in autumn. The survival rate of L.rigidum seeds was significantly lower than that of L.multiflorum, particularly in paddy soil. Factors contributing to seed mortality may include the decay or early germination of L.rigidum seeds under Japan’s high rainfall conditions. This study emphasises the importance of considering local environmental factors alongside climate niche modelling in the risk assessment of invasive species. Moreover, the integration of species distribution modelling for large-scale evaluations and manipulation experiments for fine-scale assessments proved effective in identifying climatic conditions and species traits influencing the success or failure of alien species invasion.

Abstract  Background and aims Crop wild relatives, exposed to strong natural selection, exhibit effective tolerance traits against stresses. While an aggressive root proliferation phenotype has long been considered advantageous for a range of stresses, it appears to be counterproductive under drought due to its high metabolic cost. Recently, a parsimonious root phenotype, metabolically more efficient, has been suggested to be better adapted to semiarid environments, although it is not clear that this phenotype is a trait exhibited by crop wild relatives. Methods Firstly, we analysed the root phenotype and carbon metabolism in four Medicago crop wild relatives adapted to a semiarid environment and compared them with the cultivated M. truncatula Jemalong (A17). Secondly, we exposed the cultivated (probably the least adapted genotype to aridity) and the wild (the most common one in arid zones) M. truncatula genotypes to water deficit. The carbon metabolism response in different parts of their roots was analysed. Results A reduced carbon investment per unit of root length was a common trait in the four wild genotypes, indicative of an evolution towards a parsimonious root phenotype. During the water deficit experiment, the wild M. truncatula showed higher tolerance to drought, along with a superior ability of its taproot to partition sucrose and enhanced capacity of its fibrous roots to maintain sugar homeostasis. Conclusion A parsimonious root phenotype and the spatial specialization of root carbon metabolism represent two important drought tolerance traits. This work provides relevant findings to understand the response of Medicago species roots to water deficit.

The use of non-pollen palynomorphs (NPP), particularly fossil fungi and algae, as palaeobiological proxies for Late Cretaceous palaeoenvironmental and palaeoclimatic reconstructions of warm-to-hot greenhouse conditions, can enhance our understanding of climate change impacts on modern Patagonian environments. This study aimed to reconstruct the Maastrichtian palaeoenvironment and palaeoclimate in the Cañadón Asfalto Basin (CAB, Chubut Province) by testing these NPPs as proxies using the Nearest Living Relative method (NLR). Moreover, using modern ecological requirements from open-source databases, such as GBIF and processing it with an open-source, cross-platform tool like QGIS, linked with Köppen-Geiger shapefiles, provided evidence of climate-driven palaeo-distribution patterns of fungal and algal diversity at CAB. Applying modern ecological requirements and biogeographic distribution data, we reconstructed the palaeoclimate as temperate with evenly distributed precipitation and warm summers, corresponding to the Cfb climate zone in Köppen-Geiger classifications. Additionally, our methodology produced reliable results regarding Cenozoic floras’ physiognomies based on fossil fungi, revealing a transition from sparsely wooded areas with palms and prairies to complex forest ecosystems with palms, deciduous trees, and shrubland. Furthermore, testing Cretaceous algae with the NLR method, for the first time, provided comprehensive insights into past water body characteristics, including trophic state and water quality.

Abstract After many decades of effective control of stem rust caused by the Puccinia graminis f.sp. tritici, (hereafter Pgt) the reported emergence of race TTKSK/Ug99 of Pgt in Uganda reignited concerns about epidemics worldwide because ∼90% of world wheat cultivars had no resistance to the new race. Since it was initially detected in Uganda in 1998, Ug99 variants have now been identified in thirteen countries in Africa and the Middle East. Stem rust has been a major problem in the past, and concern is increasing about the risk of return to Central and East Asia. Whilst control programs in North America and Europe relied on the use of resistant cultivars in combination with eradication of barberry (Berberis spp.), the alternate host required for the stem rust pathogen to complete its full lifecycle, the focus in East Asia was principally on the use of resistant wheat cultivars. Here, we investigate potential airborne transmission pathways for stem rust outbreaks in the Middle East to reach East Asia using an integrated modelling framework combining estimates of fungal spore deposition from an atmospheric dispersion model, environmental suitability for spore germination, and crop calendar information. We consider the role of mountain ranges in restricting transmission pathways, and we incorporate a representation of a generic barberry species into the lifecycle. We find viable transmission pathways to East Asia from the Middle East to the north via Central Asia and to the south via South Asia and that an initial infection in the Middle East could persist in East Asia for up to three years due to the presence of the alternate host. Our results indicate the need for further assessment of barberry species distributions in East Asia and appropriate methods for targeted surveillance and mitigation strategies should stem rust incidence increase in the Middle East region.

Pinyon–juniper (PJ) woodlands are among the most widespread ecosystems in rangelands of western North America, supporting diverse wildlife habitat, recreation, grazing, and cultural/spiritual enrichment. Anticipating future distribution shifts under changing climate will be critical to climate adaptation and conservation efforts in these ecosystems. Here, we evaluate drivers of PJ tree species’ distributions and project changes in response to future climate change. We developed species distribution models with dryland-focused predictors to project environmental suitability changes across the entirety of three pinyon and six juniper species ranges. We identify areas of robust suitability change by combining suitability projections from multiple emissions scenarios and time periods. PJ species’ suitabilities respond to many temperature and moisture covariates expected to change in the future. Projected responses among PJ species are highly variable, ranging from modest declines with concurrent gains for overall little net change to wide-ranging declines with no gains for overall range contractions. Environmental suitability is projected to decline broadly across the arid United States Southwest and remain relatively stable across the northern Great Basin and Colorado Plateau. Our results suggest unique responses of PJ species to future climate change. We found that species were projected to experience more losses than gains in suitability, for overall range shrinks rather than shifts. Land managers have the capacity to increase woodland resilience to drought, and our results can inform rangeland-wide management planning and conservation efforts in PJ woodlands.

Nonnative invasive plants (weeds) negatively impact native ecosystems, and their effects are likely to increase with continuing global trade. Biological weed control has been employed as a cost-effective and sustainable management option for weeds in the USA since 1902. Biological control programs require careful prioritization of target weeds to ensure the most appropriate targets are selected to obtain the greatest beneficial outcomes with available resources. The Biological Control Target Selection (BCTS) system was developed by researchers in South Africa as an objective, transparent approach to prioritizing new weed biological control targets. The BCTS system was recently modified and applied to 295 state-regulated weeds in the western USA for which no biological control agents have yet been released. This paper presents the results of that application, identifying the most suitable candidates for new biological control programs as well as problematic weeds for which the likelihood of successful biological control is low.Top-ranked species in the western USA are biennial or perennial weeds that occur in stable habitats, are established in more than one state, have traits deemed difficult to control with conventional methods, have large negative impacts and no conflicts of interest outside of the horticultural industry, and have substantial information available on potential biocontrol agents. Fifteen of the 20 top-ranked species are already targets of ongoing biological control programs in the USA. When species with current programs are excluded from the analysis, the next 20 top-ranked species largely differ by having less information available on potential biological control agents and having native or economically important congeners in the USA. Results from this framework provide valuable insights to the prioritization of current and future biocontrol research programs in the western USA.

Saussurea is one of the largest and most rapidly evolving genera within the Asteraceae, comprising approximately 520 species from the Northern Hemisphere. A comprehensive infrageneric classification, supported by robust phylogenetic trees and corroborated by morphological and other data, has not yet been published. For the first time, we recovered a well-resolved nuclear phylogeny of Saussurea consisting of four main clades, which was also supported by morphological data. Our analyses show that ancient hybridization is the most likely source of deep cytoplasmic-nuclear conflict in Saussurea, and a phylogeny based on nuclear data is more suitable than one based on chloroplast data for exploring the infrageneric classification of Saussurea. Based on the nuclear phylogeny obtained and morphological characters, we proposed a revised infrageneric taxonomy of Saussurea, which includes four subgenera and 13 sections. Specifically, 1) S. sect. Cincta, S. sect. Gymnocline, S. sect. Lagurostemon, and S. sect. Strictae were moved from S. subg. Saussurea to S. subg. Amphilaena, 2) S. sect. Pseudoeriocoryne was moved from S. subg. Eriocoryne to S. subg. Amphilaena, and 3) S. sect. Laguranthera was moved from S. subg. Saussurea to S. subg. Theodorea.

As an invasive plant, Solanum elaeagnifolium has posed a serious threat to agriculture and natural ecosystems worldwide. In order to better manage and limit its spread, we established niche models by combining distribution information and climate data from the native and invasive ranges of S. elaeagnifolium to analyze its niche changes during its colonization. Additionally, we evaluated its global invasion risk. Our results showed that the distribution of S. elaeagnifolium is affected by temperature, precipitation, altitude, and human activities. Solanum elaeagnifolium exhibits different degrees of niche conservatism and niche shift in different invasion ranges.During the global invasion of S. elaeagnifolium, both the niche shift and conservatism were observed, however, niche shift was particularly significant due to the presence of unoccupied niches (niche unfilling). Solanum elaeagnifolium generally occupied a relatively stable niche. However, a notable expansion was observed primarily in Europe and China. In Australia and Africa, its niche largely remains a subset of its native niche. Compared to the niche observed in its native range, its realized niche in China and Europe has shifted toward lower temperature and higher precipitation levels. Conversely, in Africa, the niche has shifted toward lower precipitation levels, while in Australia, it has shifted toward higher temperature. Our model predicted that S. elaeagnifolium has high invasion potential in many countries and regions. The populations of S. elaeagnifolium in China and Africa have reached the adapted stage, while the populations in Australia and Europe are currently in the stabilization stage. In addition, our research suggests that the potential distribution of S. elaeagnifolium will expand further in the future as the climate warms. All in all, our study suggests that S. elaeagnifolium has high potential to invade globally. Due to its high invasive potential, global surveillance and preventive measures are necessary to address its spread.

We assessed changes in fundamental climate‐niche space for lizard and snake species in western North America under modeled climate scenarios to inform natural resource managers of possible shifts in species distributions. We generated eight distribution models for each of 130 snake and lizard species in western North America under six time‐by‐climate scenarios. We combined the highest‐performing models per species into a single ensemble model for each scenario. Maps were generated from the ensemble models to depict climate‐niche space for each species and scenario. Patterns of species richness based on climate suitability and niche shifts were calculated from the projections at the scale of the entire study area and individual states and provinces, from Canada to Mexico. Squamate species' climate‐niche space for the recent‐time climate scenario and published known ranges were highly correlated (r = 0.81). Overall, reptile climate‐niche space was projected to move northward in the future. Sixty‐eight percent of species were projected to expand their current climate‐niche space rather than to shift, contract, or remain stable. Only 8.5% of species were projected to lose climate‐niche space in the future, and these species primarily occurred in Mexico and the southwestern U.S. We found few species were projected to lose all suitable climate‐niche space at the state or province level, although species were often predicted to occupy novel areas, such as at higher elevations. Most squamate species were projected to increase their climate‐niche space in future climate scenarios. As climate niches move northward, species are predicted to cross administrative borders, resulting in novel conservation issues for local landowners and natural resource agencies. However, information on species dispersal abilities, landscape connectivity, biophysical tolerances, and habitat suitability is needed to contextualize predictions relative to realized future niche expansions.