Charles Russell Orcutt

Modelling was carried out using maximum entropy model (MaxEnt) to explore and predict the invasion potential of littleseed canarygrass (Phalaris minor Retz.) in India under current as well as future climatic conditions under Representative Concentration Pathways (RCPs) 4.5 and 8.5 for the years 2050 and 2070. Mutually least correlated 8 bioclimatic variables along with soil and elevation data were used for the modelling over 223 occurrence locations of the species. Jackknife test revealed the significance of temperature derived variables viz. temperature seasonality, annual mean temperature and minimum temperature of the coldest month in governing the potential distribution of P. minor. Currently, 21% of India’s area is either highly (9%) or moderately (12%) suitable as habitat for P. minor. Our model predicts approximately 90% contraction in the area considered to be highly or moderately suitable climatically between 2050 and 2070 under both moderate and high emissions scenarios. Thus, under future climate, a significant niche shift by the species and decreased suitability was observed compared to the current distribution. The present study is first of its kind in exploring the invasion potential of alien invasive weed P. minor under climate change scenarios which is a current threat to rice-wheat system in Indo-Gangetic plains of India.

Declining insect abundance is occurring around the world, and some management projects are aiming to utilize roadsides and other right-of-ways as insect conservation areas. In the US, the decline of the monarch butterfly (Danaus plexippus Linnaeus [Nymphalidae]) populations has led to multiple studies focusing on a small number of milkweed species (Asclepias [Apocynaceae]) that occur in the major flyways. Here we survey a poorly studied milkweed, bract milkweed (A. brachystephana Engelm. ex Torr.), to document where it grows, which organisms make use of the plants, seed production, and concentrations of milkweed toxins (cardenolides) and to investigate if this species is suitable for roadside or right-of-ways management projects. Our results show that the range of A. brachystephana includes the Chihuahuan Desert and neighboring ecoregions. Plant populations were also observed occurring on roadsides and right-of-ways, rarely spreading into neighboring habitats. We document a variety of native pollinators utilizing floral resources and a few herbivores feeding on plant tissue. Chemical analyses show wild plants produce higher concentrations of toxic cardenolide than many other milkweed species. These data suggest A. brachystephana should be considered for roadside and right-of-way plantings, restoration projects, or seeding throughout the Chihuahuan Desert and adjoining ecoregions.

Many studies have quantified ecological impacts of individual foundation species (FS). However, emerging data suggest that FS often co‐occur, potentially inhibiting or facilitating one another, thereby causing indirect, cascading effects on surrounding communities. Furthermore, global warming is accelerating, but little is known about how interactions between co‐occurring FS vary with temperature.Shallow aquatic sedimentary systems are often dominated by three types of FS: slower‐growing clonal angiosperms, faster‐growing solitary seaweeds, and shell‐forming filter‐ and deposit‐feeding bivalves. Here, we tested the impacts of one FS on another by analyzing manipulative interaction experiments from 148 papers with a global meta‐analysis.We calculated 1,942 (non‐independent) Hedges’ g effect sizes, from 11,652 extracted values over performance responses, such as abundances, growths or survival of FS, and their associated standard deviations and replication levels. Standard aggregation procedures generated 511 independent Hedges’ g that was classified into six types of reciprocal impacts between FS.We found that (i) seaweeds had consistent negative impacts on angiosperms across performance responses, organismal sizes, experimental approaches, and ecosystem types; (ii) angiosperms and bivalves generally had positive impacts on each other (e.g., positive effects of angiosperms on bivalves were consistent across organismal sizes and experimental approaches, but angiosperm effect on bivalve growth and bivalve effect on angiosperm abundance were not significant); (iii) bivalves positively affected seaweeds (particularly on growth responses); (iv) there were generally no net effects of seaweeds on bivalves (except for positive effect on growth) or angiosperms on seaweeds (except for positive effect on ‘other processes’); and (v) bivalve interactions with other FS were typically more positive at higher temperatures, but angiosperm‐seaweed interactions were not moderated by temperature.Synthesis: Despite variations in experimental and spatiotemporal conditions, the stronger positive interactions at higher temperatures suggest that facilitation, particularly involving bivalves, may become more important in a future warmer world. Importantly, addressing research gaps, such as the scarcity of FS interaction experiments from tropical and freshwater systems and for less studied species, as well as testing for density‐dependent effects, could better inform aquatic ecosystem conservation and restoration efforts and broaden our knowledge of FS interactions in the Anthropocene.

A diverse group of invasive grasses from tropical and subtropical Africa and Asia has spread throughout the Neotropics over the last decades. Despite their strong ecological impact, current and future distribution patterns of these grasses in the region according to climate change is poorly investigated. We chose ten high potential invasive grass species and used ecological niche modeling to project their geographic distribution within the Neotropics under four climate change scenarios (current, SSP1-2.6, SSP3-7.0 and SSP5-8.5 for 2100). Current climatically suitable areas for these invasive species were estimated to account for 51.3% of the Neotropics. Projections of future climatically suitable areas ranged between 47.0% and 57.6%, depending on the climate scenario. Range retractions are projected for Melinis repens and Urochloa decumbens regardless of the SSP scenario, while Arundo donax, Hyparrhenia rufa and Melinis minutiflora are expected to expand their range in all SSP scenarios. Currently, these ten invasive species have suitable areas that greatly overlap in dry regions of the Neotropics, mainly in the savannas of Central Brazil and Central America. However, a reduction in species overlap and a geographical expansion towards wetter regions is expected under the SSP1 and SSP3 scenarios, and towards drier regions under the SSP5 scenario.

Mexico harbors ~45% of world’s cacti species richness. Their biogeography and phylogenomics were integrated to elucidate the evolutionary history of the genera Coryphantha, Escobaria, Mammillaria, Mammilloydia, Neolloydia, Ortegocactus, and Pelecyphora (Mammilloid Clade). We analyzed 52 orthologous loci from 142 complete genomes of chloroplast (103 taxa) to generate a cladogram and a chronogram; in the latter, the ancestral distribution was reconstructed with the Dispersal-Extinction-Cladogenesis model. The ancestor of these genera arose ~7 Mya on the Mexican Plateau, from which nine evolutionary lineages evolved. This region was the site of 52% of all the biogeographical processes. The lineages 2, 3 and 6 were responsible for the colonization of the arid southern territories. In the last 4 Mya, the Baja California Peninsula has been a region of prolific evolution, particularly for lineages 8 and 9. Dispersal was the most frequent process and vicariance had relevance in the isolation of cacti distributed in the south of Mexico. The 70 taxa sampled as Mammillaria were distributed in six distinct lineages; one of these presumably corresponded to this genus, which likely had its center of origin in the southern part of the Mexican Plateau. We recommend detailed studies to further determine the taxonomic circumscription of the seven genera.

Mesoamerican mountains are important centers of endemism and diversity of epiphytes. The Sierra Madre of Chiapas in southeastern Mexico is a mountainous region of great ecological interest due to its high biological richness. We present the first checklist of epiphytes for this region based on a compilation of various information sources. In addition, we determined the conservation status for each species based on the Mexican Official Standard (NOM-059-SEMARNAT-2010), endemism based on geopolitical boundaries, spatial completeness with inventory completeness index, richness distribution with range maps, and the relationship between climatic variables (temperature and rainfall) with species richness using generalized additive models. Our dataset includes 9,799 records collected between 1896-2017. Our checklist includes 708 epiphytes within 160 genera and 26 families; the most species-rich family was Orchidaceae (355 species), followed by Bromeliaceae (82) and Polypodiaceae (79). There were 74 species within a category of risk and 59 species considered endemic. Completeness of epiphyte richness suggests that sampling is still largely incomplete, particularly in the lower parts of the mountain system. Species and family range maps show the highest richness at high elevations, while geographically richness increases towards the southeast. Epiphyte richness increases with increased rainfall, although a unimodal pattern was observed along the temperature gradient with a species richness peak between 16-20 C°. The Sierra Madre of Chiapas forms a refuge to more than 40% of all epiphytes reported for Mexico and its existing network of protected areas overlaps with the greatest epiphyte richness.

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.

Abstract Barriers to reproduction are often how progress in speciation is measured. Nonetheless, an unresolved question concerns the extent to which reproductive barriers diminish gene flow between incipient species. The Sierra Nevada foothill endemic Mimulus glaucescens and the widespread M. guttatus are considered distinct species based on striking differences in vegetative morphology, but barriers to reproduction have not been previously identified, nor has gene flow between species been characterized. Here, we examined 15 potential reproductive barriers within a Northern California area of broad sympatry. Most barriers, with the exception of ecogeographic isolation, were weak or absent, and total isolation for each species was incomplete. Population genomic analyses of range-wide and broadly sympatric accessions revealed extensive gene flow between these taxa, particularly in sympatry. Despite widespread introgression, Mimulus glaucescens, emerged as monophyletic and largely comprised a single ancestry that was found at intermediate frequency within M. guttatus. This result, along with observed ecological and phenotypic differentiation, suggests that natural selection may contribute to the maintenance of distinct phenotypic forms in the earliest stages of speciation. Integrating estimates of barrier strength with direct estimates of gene flow can strengthen a more nuanced interpretation of the process of speciation in natural communities.

Species climate niche models (CNMs) have been widely used for assessing climate change impact, developing conservation strategies and guiding assisted migration for adaptation to future climates. However, the CNMs built based on species occurrence data only reflect the species’ realized niche, which can overestimate the potential loss of suitable habitat of existing forests and underestimate the potential of assisted migration to mitigate climate change. In this study, we explored building a fundamental climate niche model using widely available species occurrence data with two important forest tree species, lodgepole pine (Pinus contorta Dougl. ex Loud.) and Douglas-fir (Pseudotsuga menziesii Franco.), which were introduced to many countries worldwide. We first compared and optimized three individual modeling techniques and their ensemble by adjusting the ratio of presence to absence (p/a) observations using an innovative approach to predict the realized climate niche of the two species. We then extended the realized climate niches to their fundamental niches by determining a new cut-off threshold based on species occurrence data beyond the native distributions. We found that the ensemble model comprising Random Forest and Maxent had the best performance and identified a common cut-off threshold of 0.3 for predicting the fundamental climate niches of the two species, which is likely applicable to other species. We then predicted the fundamental climate niches of the two species under current and future climate conditions. Our study demonstrated a novel approach for predicting species’ fundamental climate niche with high accuracy using only species occurrence data, including both presence and absence data points. It provided a new tool for assessing climate change impact on the future loss of existing forests and implementing assisted migration for better adapting to future climates.

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.