John William Harshberger

Prunus persica (peach), a well-known fruit species belonging to the family Rosaceae, has a long history of human consumption. Its hard and easily preserved fruitstones (endocarps) have often been found at archaeological sites in many parts of the world. However, there are several species within Prunus subg. Prunus sect. Persica with similar stone morphologies. In order to correctly identify the stones of P. persica and related taxa, we first sampled, described and analysed the stone morphological characteristics of all five species in sect. Persica , together with the related taxa P . armeniaca , P . mume and P . salicina . Then detailed fruitstone descriptions and measurements were made together with an illustrated key to the various species, to enable the identification of peaches at species level and to explore and understand the processes of domestication, cultivation and distribution of P. persica and its allies.

AbstractPremiseBiotic disjunctions have attracted scientific attention for the past 200 years. Despite being represented in many familiar plants (such as bald cypress, flowering dogwood, sweetgum, partridgeberry, etc.), the eastern North American (ENA)–Mexican (M) disjunction remains poorly understood. Major outstanding questions include the divergence times of taxa exhibiting the disjunction and environmental/geological processes that may underlie the disjunction. Symphyotrichum Nees (Asteraceae), one of the most diverse genera in the eastern USA, displays several examples of disjunct ENA–M taxa.MethodsWe generated target capture data using the Angiosperms353 baitset and generated the first well‐sampled phylogenomic hypothesis for Symphyotrichum and its close relatives. Focusing on S. subgenus Virgulus, we used MCMCTREE to perform divergence time estimation and the R package BioGeoBEARS to infer ancestral regions and biogeographic transitions between North America and Mexico. Finally, we used the ancestral niche reconstruction method Utremi to test for a role of historical aridification in generating the disjunction.ResultsOur molecular data suggest a recent radiation of Symphyotrichum at the Plio‐Pleistocene boundary (~2.5 mya), with early connections to Mexico in ancestral lineages that closed off shortly after and were followed by vicariance across this region. Except for some present‐day broadly distributed species, there is a complete lack of movement between ENA and M after ~0.5 mya.ConclusionsA reconstructed disjunct distribution of suitable habitat in Pleistocene climatic models corroborates results from biogeographic modeling and confirms glacial cycles are more likely to be associated with the breakup of ENA–M biogeographic connections.

The family Onocleaceae represents a small family of terrestrial ferns, with four genera and around five species. It has a circumboreal to north temperate distribution, and exhibits a disjunct distribution between Eurasia and North America, including Mexico. Historically, the taxonomy and classification of this family has been subject to debate and contention among scholars, leading to contradictory classifications and disagreements on the number of genera and species within the family. Furthermore, due to this disjunct intercontinental distribution and the lack of detailed study across its wide range, this family merits further study to clarify its distributional pattern. Maximum likelihood and Bayesian phylogenetic reconstructions were based on a concatenated sequence dataset for 17 plastid loci and one nuclear locus, which were generated from 106 ingroup and six outgroup taxa from three families. Phylogenetic analyses support that Onocleaceae is composed of four main clades, and Pentarhizidium was recovered as the first branching lineages in Onocleaceae. Molecular dating and ancestral area reconstruction analyses suggest that the stem group of Onocleaceae originated in Late Cretaceous, with subsequent diversification and establishment of the genera Matteuccia, Onoclea, Onocleopsis, and Pentarhizidium during the Paleogene and Neogene. The ancestors of Matteuccia, Onoclea, and Onocleopsis could have migrated to North America via the Beringian land bridge or North Atlantic land bridge which suggests that the diversification of Matteuccia + Onoclea + Onocleopsis closely aligns with the Paleocene-Eocene Thermal Maximum (PETM). In addition, these results suggest that Onocleaceae species diversity peaks during the late Neogene to Quaternary. Studies such as this enhance our understanding of the mechanisms and climatic conditions shaping disjunct distribution in ferns and lycophytes of eastern Asia, North America, and Mexico and contribute to a growing body of evidence from other taxa, to advance our understanding of the origins and migration of plants across continents.

Understanding the drivers of species richness patterns is a major goal of ecology and evolutionary biology, and the drivers vary across regions and taxa. Here, we assessed the influence of environmental factors and evolutionary history on the pattern of species richness in the genus Sorbus (110 species). We mapped the global species richness pattern of Sorbus at a spatial resolution of 200 × 200 km, using 10,652 specimen records. We used stepwise regression to assess the relationship between 23 environmental predictors and species richness and estimated the diversification rate of Sorbus based on chloroplast genome data. The effects of environmental factors were explained by adjusted R2, and evolutionary factors were inferred based on differences in diversification rates. We found that the species richness of Sorbus was highest in the Hengduan Mountains (HDM), which is probably the center of diversity. Among the selected environmental predictors, the integrated model including all environmental predictors had the largest explanatory power for species richness. The determinants of species richness show regional differences. On the global and continental scale, energy and water availability become the main driving factors. In contrast, climate seasonality is the primary factor in the HDM. The diversification rate results showed no significant differences between HDM and non-HDM, suggesting that evolutionary history may have limited impact on the pattern of Sorbus species richness. We conclude that environmental factors play an important role in shaping the global pattern of Sorbus species richness, while diversification rates have a lesser impact.

This study assesses the potential effects of climate change on the distribution of the Drosera genus, which is a carnivorous plant group widely distributed in South America. The Drosera species act as adequate biological indicators, with their fitness performance reflecting the health of ecosystems. Through the application of species distribution models and the analysis of bioclimatic variables, the adaptability of 39 Drosera species to evolving climatic conditions was assessed, revealing their capacity to thrive in diverse habitats, from nutrient-deficient soils to regions with high atmospheric CO2 concentrations. While many species show adaptability, environmental forecasts using two General Circulation Models indicate a decrease in favorable habitats by 2050 and 2070. It is expected that about 71.79 % of species will encounter shrinking habitat suitability, while 28.21 % may see an increase in habitat suitability. This anticipated habitat loss underscores the critical need for proactive conservation measures, including habitat preservation, ecological restoration, assisted migration, and genetic conservation efforts, to counteract the adverse effects of climate change. Additionally, the study highlights the importance of refining species distribution models and deepening our understanding of the ecological dynamics of Drosera species in response to environmental changes. By offering insights into the challenges and opportunities for conserving Drosera species in a changing climate, this work lays a solid groundwork for future ecological research and conservation initiatives. It calls for an integrated approach that combines scientific inquiry with strategic conservation actions to ensure the survival of these unique plant group and ecological integrity during global environmental shifts.

Cold tolerance strategies in plants vary from structural to biochemical permitting many plants to survive and grow on sites that experience freezing conditions intermittently. Although tree ferns occur predominantly across the tropics, they also occur in temperate zones and occasionally in areas that experience sub‐zero temperatures, and how these large ferns survive freezing conditions is unknown. Many temperate tree fern taxa are marcescent – retaining whorls of dead fronds encircling the upper trunk – or develop short or prostrate trunks, possibly to insulate against frost damage to their trunks and growing crowns. We asked the following questions: 1) do global growth patterns and traits of tree ferns respond to freezing conditions associated with latitude and elevation, 2) do growth patterns of tree ferns in New Zealand vary along a temperature‐related gradient, and 3) do marcescent tree fern skirts insulate the growing crown from sub‐zero temperatures? To establish what morphological adaptations permitted the Cyatheales to occur in biomes that experience intermittent sub‐zero temperatures and frost, we 1) reviewed the global distributions of these structural and morphological traits within the tree ferns (Cyatheales); 2) assessed the patterns of tree fern marcescence, and other traits potentially associated with cold tolerance (no trunk, prostrate, short‐trunked) of nine taxa of the Cyatheales along environmental gradients across New Zealand; and 3) conducted a field experiment to assess the thermal insulation properties of tree fern marcescent skirts. We identified significant trends among growth forms, marcescence, and environmental gradients consistent with our hypothesis that these are adaptations to tolerate cold. Our field experiments provide quantitative evidence that marcescent skirts have a strong insulating effect on tree fern trunks. The Cyatheales have evolved several strategies to protect the pith cores of their trunks from extreme cold temperatures in temperate forests allowing them to capture niche space in environments beyond the tropics.

Background Hybridisation is one of the processes that influence the evolutionary history of plants, including shifts in their distribution. It occurs unevenly across families, and the Cactaceae is an outstanding case displaying many natural hybrids. Aims This study evaluated the current geographical distributions of hybrids within the family and compared the potential ranges of established hybrids with those of their parental species. Methods We gathered georeferenced data of putative cactus hybrids to map their known distributions and employed ecological niche-based models (ENMs) to predict the potential ranges of established hybrids and those of their parental species. Results While hybrids in the subfamily Cactoideae were distributed broad throughout the New World, the hybrids in the subfamily Opuntioideae were present only in North America and northern South America. ENMs showed overall resemblance between potential ranges of hybrids and parental species, except for two cases, Cylindropuntia prolifera and Selenicereus setaceus, which both had lower levels of potential range overlap and significant dissimilarities compared to parental ranges. Conclusion Cactaceae should be considered a model for studying the evolutionary consequences of hybridisation by investigating physiological constraints of hybrids to colonise new habitats as well as the role that polyploidy has played in range shifts.

Salvinia minima (Salviniaceae) is here reported as a new non-native species to the flora of the Iberian Peninsula. A population was recently found in the Besòs river (Barcelona province) and a sample collected in 1999 at the Ebro Delta (Tarragona province) would also be referable to this species.

Studies on climate change need to make projections based on predicted scenarios. One source of variability in these projections is the choice of general circulation models (GCMs). There is a lack of consensus on how to choose the GCMs. This is particularly notorious in species distribution modeling (SDM) studies. An ideal approach would be to encompass all GCMs, but this is exceedingly costly in terms of computational requirements. We propose a methodological framework, which allows the researcher to evaluate the variation in GCMs. The framework has been implemented in an R package, being an easily accessible tool. The proof of concept using SDMs returned an output correlation > 0.9 with the baseline, saving > 79% of computation time and allowing a broader range of hardware to perform robust projections. The chooseGCM package provides a set of functions to download and analyze GCM data, while also providing a wrapper function, helping both experienced and novice modelers. It facilitates the application and calculation of clusterization, correlation, distances, and exploratory information and can help researchers from different backgrounds since it relies solely on the availability of GCMs projections.

We report the first record of Tarenaya spinosa (Jacq.) Raf. (spiny spider flower) as a new addition to the naturalized alien flora of Iran. Spiny spider flower is native to South and Central America and widely naturalized in the paleo-tropics (south Africa and Asia). This species was intentionally introduced to Iran in the last decade of the XX century and cultivated as an ornamental plant due to its large, peculiar, and colorful flowers. It escaped from cultivation and gradually increased its alien range in the surrounding areas, by seeds, without any direct human intervention. The UNESCOworld-heritage site Hyrcanian forests (northern Iran) includes a unique forest ecosystem which is potentially threatened by the naturalization of many alien and invasive species including this new recorded alien. Considering the potential negative impacts of this new alien species on the native biodiversity and its high reproductive potential and spread capacity, we highlight the importance of preventing new introductions, and prioritizing practices for eradication and control before it could become widespread and unmanageable.