W. Hague Harrington

Understanding the factors affecting species distributions is a central topic in ecology and biogeography. However, most research on this topic has focused on species inhabiting terrestrial environments. At broad scales, abiotic variables consistently serve as primary determinants of species’ distributions. In this study, we investigated the explanatory power of different abiotic variables in determining the distribution patterns of sea snakes on a global scale. Additionally, as the boundaries of realized thermal niches have significant implications for the ecology of species and their geographic distributions, we evaluated the asymmetry of realized thermal limits (i.e., differences in variances between the upper and lower limits of the realized thermal niche). We obtained 10 marine environmental variables from global databases along with >5000 occurrence records for 51 sea snake species in 4 genera across the group’s entire known geographic range. Using these data, we employed correlative ecological niche modeling to analyze the influence of the individual variables in explaining species’ distributions. To estimate the realized thermal limits of each species, we extracted the mean, minimum, and maximum temperature values at four depths (superficial, mean benthic, minimum benthic, and maximum benthic) for each occurrence record of the species. We then evaluated the asymmetry of the realized thermal niche by measuring and comparing the variances in the upper and lower limits. Both analyses (the importance of variables and realized thermal limit asymmetry) were performed at three taxonomic levels (sea snakes as a lineage of marine-adapted elapids [true sea snakes + sea kraits], subfamily, and genus) and two spatial resolutions. Overall, we found that temperature, silicate, nitrate, salinity, and phosphate concentrations were the most influential factors in explaining the spatial distribution patterns of sea snakes, regardless of taxonomic level or spatial resolution. Similarly, we observed that the realized thermal limits were asymmetric, with a higher variance in the lower limits, and that asymmetry decreased as the taxonomic level and spatial resolution increased.

The genetic composition of founding populations is likely to play a key role in determining invasion success. Individual genotypes may differ in habitat preference and environmental tolerance, so their ability to colonize novel environments can be highly variable. Despite the importance of genetic variation on invasion success, its influence on the potential distribution of invaders is rarely investigated. Here, we integrate population genomics and ecological niche models (ENMs) into a single framework to predict the distribution of globally invasive common ragweed (Ambrosia artemisiifolia) in Australia. We identified three genetic clusters for ragweed and used these to construct cluster‐specific ENMs and characterize within‐species niche differentiation. The potential range of ragweed in Australia depended on the genetic composition and continent of origin of the introduced population. Invaders originating from warmer, wetter climates had a broader potential distribution than those from cooler, drier ones. By quantifying this change, we identified source populations most likely to expand the ragweed distribution. As prevention remains the most effective method of invasive species management, our work provides a valuable way of ranking the threat posed by different populations to better inform management decisions.

The threat of invasive species to biodiversity and ecosystem structure is exacerbated by the increasingly concerning outlook of predicted climate change and other human influences. Developing preventative management strategies for invasive plant species before they establish is crucial for effective management. To examine how climate change may impact habitat suitability, we modeled the current and future habitat suitability of two terrestrial species, Geranium lucidum and Pilosella officinarum , and two aquatic species, Butomus umbellatus and Pontederia crassipes , that are relatively new invasive plant species regionally, and are currently spreading in the Pacific Northwest (PNW, North America), an area of unique natural areas, vibrant economic activity, and increasing human population. Using North American presence records, downscaled climate variables, and human influence data, we developed an ensemble model of six algorithms to predict the potential habitat suitability under current conditions and projected climate scenarios RCP 4.5, 7.0, and 8.5 for 2050 and 2080. One terrestrial species ( P. officinarum ) showed declining habitat suitability in future climate scenarios (contracted distribution), while the other terrestrial species ( G. lucidum ) showed increased suitability over much of the region (expanded distribution overall). The two aquatic species were predicted to have only moderately increased suitability, suggesting aquatic plant species may be less impacted by climate change. Our research provides a template for regional-scale modelling of invasive species of concern, thus assisting local land managers and practitioners to inform current and future management strategies and to prioritize limited available resources for species with expanding ranges.

Determining whether the climatic ecological niche of an invasive alien plant is similar to that of the niche occupied by its native population (ecological niche conservatism) is essential for predicting the plant invasion process. Ragweed (Ambrosia artemisiifolia L.) usually poses serious threats to human health, agriculture, and ecosystems within its newly occupied range. We calculated the overlap, stability, unfilling, and expansion of ragweed’s climatic ecological niche using principal component analysis and performed ecological niche hypothesis testing. The current and potential distribution of A. artemisiifolia was mapped by ecological niche models to identify areas in China with the highest potential risk of A. artemisiifolia invasion. The high ecological niche stability indicates that A. artemisiifolia is ecologically conservative during the invasion. Ecological niche expansion (expansion = 0.407) occurred only in South America. In addition, the difference between the climatic and native niches of the invasive populations is mainly the result of unpopulated niches. The ecological niche model suggests that southwest China, which has not been invaded by A. artemisiifolia, faces an elevated risk of invasion. Although A. artemisiifolia occupies a climatic niche distinct from native populations, the climatic niche of the invasive population is only a subset of the native niche. The difference in climatic conditions is the main factor leading to the ecological niche expansion of A. artemisiifolia during the invasion. Additionally, human activities play a substantial role in the expansion of A. artemisiifolia. Alterations in the A. artemisiifolia niche would help explain why this species is so invasive in China.

Rubus (Rosaceae), one of the most complicated angiosperm genera, contains about 863 species, and is notorious for its taxonomic difficulty. The most recent (1910–1914) global taxonomic treatment of the genus was conducted by Focke, who defined 12 subgenera. Phylogenetic results over the past 25 years suggest that Focke's subdivisions of Rubus are not monophyletic, and large‐scale taxonomic revisions are necessary. Our objective was to provide a comprehensive phylogenetic analysis of the genus based on an integrative evidence approach. Morphological characters, obtained from our own investigation of living plants and examination of herbarium specimens are combined with chloroplast genomic data. Our dataset comprised 196 accessions representing 145 Rubus species (including cultivars and hybrids) and all of Focke's subgenera, including 60 endemic Chinese species. Maximum likelihood analyses inferred phylogenetic relationships. Our analyses concur with previous molecular studies, but with modifications. Our data strongly support the reclassification of several subgenera within Rubus. Our molecular analyses agree with others that only R. subg. Anoplobatus forms a monophyletic group. Other subgenera are para‐ or polyphyletic. We suggest a revised subgeneric framework to accommodate monophyletic groups. Character evolution is reconstructed, and diagnostic morphological characters for different clades are identified and discussed. Based on morphological and molecular evidence, we propose a new classification system with 10 subgenera: R. subg. Anoplobatus, R. subg. Batothamnus, R. subg. Chamaerubus, R. subg. Cylactis, R. subg. Dalibarda, R. subg. Idaeobatus, R. subg. Lineati, R. subg. Malachobatus, R. subg. Melanobatus, and R. subg. Rubus. The revised infrageneric nomenclature inferred from our analyses is provided along with synonymy and type citations. Our new taxonomic backbone is the first systematic and complete global revision of Rubus since Focke's treatment. It offers new insights into deep phylogenetic relationships of Rubus and has important theoretical and practical significance for the development and utilization of these important agronomic crops.

Paleoclimate reconstructions can provide a window into the environmental conditions in Earth history when atmospheric carbon dioxide concentrations were higher than today. In the eastern USA, paleoclimate reconstructions are sparse, because terrestrial sedimentary deposits are rare. Despite this, the eastern USA has the largest population and population density in North America, and understanding the effects of current and future climate change is of vital importance. Here, we provide terrestrial paleoclimate reconstructions of the eastern USA from Miocene fossil floras. Additionally, we compare proxy paleoclimate reconstructions from the warmest period in the Miocene, the Miocene Climatic Optimum (MCO), to those of an MCO Earth System Model. Reconstructed Miocene temperatures and precipitation north of 35°N are higher than modern. In contrast, south of 35°N, temperatures and precipitation are similar to today, suggesting a poleward amplification effect in eastern North America. Reconstructed Miocene rainfall seasonality was predominantly higher than modern, regardless of latitude, indicating greater variability in intra-annual moisture transport. Reconstructed climates are almost uniformly in the temperate seasonal forest biome, but heterogeneity of specific forest types is evident. Reconstructed Miocene terrestrial temperatures from the eastern USA are lower than modeled temperatures and coeval Atlantic sea surface temperatures. However, reconstructed rainfall is consistent with modeled rainfall. Our results show that during the Miocene, climate was most different from modern in the northeastern states, and may suggest a drastic reduction in the meridional temperature gradient along the North American east coast compared to today.

Cultivated plants provide food, fiber, and energy but they can escape, de-domesticate, colonize agroecosystems as weeds, and disrupt natural ecosystems as invasive species. Escape and invasion depend on traits of the species, type and rate of domestication, and cultivation context. Understanding this “de-domestication invasion process” is critical for managing conservation efforts to reduce unintended consequences of cultivated species in novel areas. Cannabis (Cannabis sativa L.) is an ideal case study to explore this process because it was one of the earliest plants to co-evolve with humans, has a crop to weed history, and has been introduced and cultivated globally. Moreover, recent liberalization of cannabis cultivation and use policies have raised concerns about invasion risk. Here, we synthesize knowledge on cannabis breeding, cultivation, and processing relevant to invasion risk and outline research and management priorities to help overcome the research deficit on the invasion ecology of the species. Understanding the transition of cannabis through the de-domestication-invasion process will inform policy and minimize agricultural and environmental risks associated with cultivation of domesticated species.

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).

Climate change is now a reality and is altering ecosystems, with Canada experiencing 2–4 times the global average rate of warming. This will have a critical impact on berry cultivation and horticulture. Enhancing our understanding of how wild and cultivated berries will perform under changing climates will be essential to mitigating impacts on ecosystems, culture and food security. Our objective was to predict the impact of climate change on habitat suitability of four berry producing Vaccinium species: two species with primarily northern distributions (V. uliginosum, V. vitis-idaea), one species with a primarily southern distribution (V. oxycoccos), and the commercially cultivated V. macrocarpon. We used the maximum entropy (Maxent) model and the CMIP6 shared socioeconomic pathways (SSPs) 126 and 585 projected to 2041–2060 and 2061–2080. Wild species showed a uniform northward progression and expansion of suitable habitat. Our modeling predicts that suitable growing regions for commercial cranberries are also likely to shift with some farms becoming unsuitable for the current varieties and other regions becoming more suitable for cranberry farms. Both V. macrocarpon and V. oxycoccos showed a high dependence on precipitation-associated variables. Vaccinium vitis-idaea and V. uliginosum had a greater number of variables with smaller contributions which may improve their resilience to individual climactic events. Future competition between commercial cranberry farms and wild berries in protected areas could lead to conflicts between agriculture and conservation priorities. New varieties of commercial berries are required to maintain current commercial berry farms.

Speciation through niche divergence often occurs as lineages of organisms colonize and adapt to new environments with novel ecological opportunities that facilitate the evolution of ecologically different phenotypes. In snakes, adaptive diversification may be driven by the evolution of traits relating to changes in their diets. Accordingly, habitatmediated differences in prey available to ancestral snakes as they colonized and occupied novel dynamic landscapes are likely to have been a strong selective agent behind the divergence and radiation of snakes across the globe. Using an ancestral reconstruction approach that considers the multivariate nature of ecological phenotypes while accounting for sampling variation between taxa, we explored how diet and macro-habitat use coevolved across a phylogeny of 67 species of Afro-Asian colubrine snakes. Our results show that the most recent common ancestor of this clade was likely a dietary generalist that occupied tropical forests in Asia. Deviations from this generalist diet to a variety of specialist diets each dominated by the utilization of single prey types repeatedly occurred as ancestral colubrines shifted from tropical forests to savanna and grassland habitats across Africa. We additionally found that dietary specialist species were on average smaller in maximum length than dietary generalists, congruent with established predator-size, preydiversity dynamics in snakes. We speculate that adaptive divergence in ancestral colubrines arose as a result of a selective regime that favored diets comprised of terrestrial prey, and that partitioning of different prey types led to the various forms of dietary specialization evident in these lineages today. Our findings provide new insights into the ecological correlates associated with the evolution of diet in snakes, thereby furthering our understanding of the driving forces behind patterns of snake diversification.