Walter Jacob Eyerdam

Abstract The Neotropics have been host to a myriad of geological and climatic events that have shaped the biodiversity present in the region. Bromeliaceae forms one of the most prominent components of the Neotropical flora, being considered the largest group nearly exclusive to the Americas, with almost 4000 species divided into eight subfamilies. Here, we utilize a new time-calibrated molecular phylogeny including 1268 bromeliad taxa and integrate habitat and morphological data to answer the following questions: (i) Are bromeliad subfamilies monophyletic, and did Neogene and Quaternary events in South America coincide with their divergence? (ii) Did naked seeds of berry-fruited species, epiphytic growth, and climatic factors increase bromeliad diversification? Our analysis reconstructed a new topology concerning some recently diverged lineages, with the genus Bromelia emerging as the sister group of a clade including all remaining Bromelioideae lineages + Puyoideae. Miocene events possibly triggered the diversification of bromeliads after a long period of stasis during the Palaeogene. We hypothesize that the morphological shift between Bromelia and Bromelioideae (except Bromelia) is related to the colonization of a new high-elevation environment by Puyoideae in the Andes. Additionally, our results show that naked seeds and the epiphytic growth form positively influence diversification rate, while precipitation, temperature, and elevation have a negative influence. We emphasize the importance of considering a variety of morphological and ecological features to enhance our understanding of bromeliad evolution.

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 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.

To address the remaining knowledge gap regarding the distribution of seagrasses in Ireland, this study aimed a) to create an updated seagrass (Zostera spp.) distribution map, and b) to evaluate the environmental quality to which seagrass meadows are exposed. To achieve the first objective, we (i) combined the available data on seagrass distribution published to date, and (ii) mapped additional meadows by implementing an integrated method based on species distribution models, satellite-derived images, and snorkelling-based surveys. We mapped 209 new seagrass meadows (14.98 km2), representing a 37.03 % increase over previously reported extents. Consequently, the total extent of Irish seagrass meadows is estimated to be at least 54.85 km2. To address the second objective, we assessed the level of anthropogenic pressure of seagrass meadows based on the index provided by the Water Framework Directive of the European Environment Agency. This study demonstrates that Irish meadows are primarily located in areas with ‘HIGH’ and ‘GOOD’ water status.

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.

In this study, we explored the distributions of grass genera in the Southern Cone (SC) of South America, applying several phylogenetic diversity (PD) metrics and randomization tests. Grasses appear to have been present in South America since their early evolution as tropical understory species more than 60 Ma. During the course of evolution, grasses have adapted to all terrestrial biomes and become one of the most successful plant families on earth. At present, the SC contains nearly all terrestrial biomes and a wide range of humid to arid ecoregions. Analyzing 126.514 point occurrences and four plastid markers for 148 genera (91% of the native grass genera), we found that tropical humid regions hold the highest PD, with no observed bias in branch lengths. These results indicate that niche conservatism dominates the diversity pattern of grasses in the SC. We found significantly low PD in the Dry Chaco and in the Patagonian Steppe, which suggest ecological filtering in both warm and cold arid regions. The Patagonian Steppe also holds significantly longer branches than expected by chance, as the native grass flora is mainly composed of distantly related Pooideae genera with a northern hemisphere origin. Short branches are found in the Uruguayan Savanna, suggesting that these grasslands could be a cradle for grass diversity within the SC. The dated phylogeny supported the current view of a relatively recent evolution of the family within the SC, with most diversification taking place from the middle Miocene and onwards.

Non‐native annual grasses can dramatically alter fire frequency and reduce forage quality and biodiversity in the ecosystems they invade. Effective management techniques are needed to reduce these undesirable invasive species and maintain ecosystem services. Well‐timed management strategies, such as grazing, that are applied when invasive grasses are active prior to native plants can control invasive species spread and reduce their impact; however, anticipating the timing of key phenological stages that are susceptible to management over vast landscapes is difficult, as the phenology of these species can vary greatly over time and space. To address this challenge, we created range‐wide phenology forecasts for two problematic invasive annual grasses: cheatgrass (Bromus tectorum), and red brome (Bromus rubens). We tested a suite of 18 mechanistic phenology models using observations from monitoring experiments, volunteer science, herbarium records, timelapse camera imagery, and downscaled gridded climate data to identify the models that best predicted the dates of flowering and senescence of the two invasive grass species. We found that the timing of flowering and senescence of cheatgrass and red brome were best predicted by photothermal time models that had been adjusted for topography using gridded continuous heat‐insolation load index values. Phenology forecasts based on these models can help managers make decisions about when to schedule management actions such as grazing to reduce undesirable invasive grasses and promote forage production, quality, and biodiversity in grasslands; to predict the timing of greatest fire risk after annual grasses dry out; and to select remote sensing imagery to accurately map invasive grasses across topographic and latitudinal gradients. These phenology models also have the potential to be operationalized for within‐season or within‐year decision support.