Speciation Events Research Articles

Drivers of diversification in Linum (Linaceae) by means of chromosome evolution: correlations with biogeography, breeding system and habit.

Chromosome evolution leads to hybrid dysfunction and recombination patterns and has thus been proposed as a major driver of diversification in all branches of the tree of life, including flowering plants. In this study we used the genus Linum (flax species) to evaluate the effects of chromosomal evolution on diversification rates and on traits that are important for sexual reproduction. Linum is a useful study group because it has considerable reproductive polymorphism (heterostyly) and chromosomal variation (n = 6-36) and a complex pattern of biogeographical distribution. We tested several traditional hypotheses of chromosomal evolution. We analysed changes in chromosome number across the phylogenetic tree (ChromEvol model) in combination with diversification rates (ChromoSSE model), biogeographical distribution, heterostyly and habit (ChromePlus model). Chromosome number evolved across the Linum phylogeny from an estimated ancestral chromosome number of n = 9. While there were few apparent incidences of cladogenesis through chromosome evolution, we inferred up to five chromosomal speciation events. Chromosome evolution was not related to heterostyly but did show significant relationships with habit and geographical range. Polyploidy was negatively correlated with perennial habit, as expected from the relative commonness of perennial woodiness and absence of perennial clonality in the genus. The colonization of new areas was linked to genome rearrangements (polyploidy and dysploidy), which could be associated with speciation events during the colonization process. Chromosome evolution is a key trait in some clades of the Linum phylogeny. Chromosome evolution directly impacts speciation and indirectly influences biogeographical processes and important plant traits.

New records of cave-dwelling populations of Rhamdia catfishes (Siluriformes, Heptapteridae) from Chiapas, Mexico

Dedicated ichthyological surveys in four active karstic caves in the Mexican state of Chiapas (Grijalva River drainage basin) resulted in the discovery of the same number of hypogean populations of Rhamdia catfishes assignable to two different species: R. laticauda and R. guatemalensis. The taxonomic identity of these populations was initially determined based on morphological traits and subsequently corroborated with molecular data in a phylogenetic framework. For the most part, these newly discovered populations exhibit partial and variable troglomorphism (vs. fixed), a pattern that has been observed in most other cave-dwelling species/populations of Mexican Rhamdia, and possibly caused by gene flow with and/or incipient speciation from epigean lineages. Since most hypogean forms of Mexican Rhamdia derive from/are part of a larger R. laticauda clade, our discovery of cave-dwelling populations assignable to R. guatemalensis is noteworthy and includes the very first record of a R. guatemalensis population with pronounced and widespread troglomorphism. Our discovery of hitherto unrecorded populations of hypogean Rhamdia highlights the continued importance of exploration in the process of documenting subterranean biodiversity, particularly in regions of the world rich with cave systems. Our findings corroborate the notion that, among Neotropical fishes, the catfish genus Rhamdia is one of the most prone and effective at colonizing subterranean habitats and establishing viable hypogean populations.

Chromosomal Rearrangements and Satellite DNAs: Extensive Chromosome Reshuffling and the Evolution of Neo-Sex Chromosomes in the Genus Pyrrhulina (Teleostei; Characiformes).

Chromosomal rearrangements play a significant role in the evolution of fish genomes, being important forces in the rise of multiple sex chromosomes and in speciation events. Repetitive DNAs constitute a major component of the genome and are frequently found in heterochromatic regions, where satellite DNA sequences (satDNAs) usually represent their main components. In this work, we investigated the association of satDNAs with chromosome-shuffling events, as well as their potential relevance in both sex and karyotype evolution, using the well-known Pyrrhulina fish model. Pyrrhulina species have a conserved karyotype dominated by acrocentric chromosomes present in all examined species up to date. However, two species, namely P. marilynae and P. semifasciata, stand out for exhibiting unique traits that distinguish them from others in this group. The first shows a reduced diploid number (with 2n = 32), while the latter has a well-differentiated multiple X1X2Y sex chromosome system. In addition to isolating and characterizing the full collection of satDNAs (satellitomes) of both species, we also in situ mapped these sequences in the chromosomes of both species. Moreover, the satDNAs that displayed signals on the sex chromosomes of P. semifasciata were also mapped in some phylogenetically related species to estimate their potential accumulation on proto-sex chromosomes. Thus, a large collection of satDNAs for both species, with several classes being shared between them, was characterized for the first time. In addition, the possible involvement of these satellites in the karyotype evolution of P. marilynae and P. semifasciata, especially sex-chromosome formation and karyotype reduction in P. marilynae, could be shown.

Thermal niche breadth and their relationship with sturnira bat species diversification

The interaction between climatic conditions and the ability of organisms to maintain homeostasis regulates the distribution of species on the planet. However, its influence on macroevolutionary dynamics is not well understood. It has been suggested that diversification rates will be different in lineages with narrow thermal niches (specialists) to diversification rates in generalist lineages, but the evidence for this is elusive. Here, we tested this hypothesis by using the most diverse (in species richness and geographic range variation) tropical bat genus within the Phyllostomidae family. We estimated the realized thermal niche breadth of Sturnira species from their geographic range and categorized them as generalists, cold specialists, or warm specialists. We compared dynamic evolutionary models that differ in 1) niche breadth evolution, 2) parental niche breadth inheritance, and 3) whether niche breadth evolution is associated with shifts in diversification rates. Our best-performing model indicates that most Sturnira species arose as specialists in warm climates and that over time, their niche breadth broadens, and just a subset of those species becomes specialists in cold environments. We found that the evolution of realized thermal niche breadth causes fluctuations in per-lineage rates of diversification, where warm specialists boast the highest speciation rates. However, we found no evidence of these changes in niche neither triggering nor being a result of speciation events themselves; this suggests that diversification events in Sturnira could instead depend on allopatric speciation processes such as the development of geographic barriers.

Genomic inference of a severe human bottleneck during the Early to Middle Pleistocene transition.

Population size history is essential for studying human evolution. However, ancient population size history during the Pleistocene is notoriously difficult to unravel. In this study, we developed a fast infinitesimal time coalescent process (FitCoal) to circumvent this difficulty and calculated the composite likelihood for present-day human genomic sequences of 3154 individuals. Results showed that human ancestors went through a severe population bottleneck with about 1280 breeding individuals between around 930,000 and 813,000 years ago. The bottleneck lasted for about 117,000 years and brought human ancestors close to extinction. This bottleneck is congruent with a substantial chronological gap in the available African and Eurasian fossil record. Our results provide new insights into our ancestry and suggest a coincident speciation event.

Local adaptation to hummingbirds and bees in Salvia stachydifolia: insights into pollinator shifts in a Southern Andean sage.

Differences among populations in pollinator assemblages can lead to local adaptation mosaics in which plants evolve different floral morphologies and attractive traits. Mountain habitats may promote local adaptation because of differences in environmental conditions with altitude, causing changes in pollinators, and because mountaintops can act as isolated habitats. We studied if the differences in floral shape, size and nectar traits in Salvia stachydifolia can be attributed to variations in the relative contribution of hummingbirds and insects. We studied eight populations of S. stachydifolia in natural and under common garden conditions, to assess whether population differences have a genetic component. We recorded pollinators, their behaviour and visitation rates, and characterized pollinator assemblages. In addition, we measured nectar volume and concentration, and collected flowers to describe floral shape and size variation using geometric morphometric methods. We then applied an unsupervised learning algorithm to identify ecotypes based on morphometric traits. Finally, we explored whether populations with different pollinator assemblages had different climatic and/or elevation preferences. We found that variation in the identity of the main pollinators was associated with differences among populations in all traits, as expected under a local adaptation scenario. These differences persisted in the common garden, suggesting that they were not due to phenotypic plasticity. We found S. stachydifolia populations were pollinated either by bees, by hummingbirds or had mixed pollination. We identified two ecotypes that correspond to the identity of the main pollinator guilds, irrespective of climate or altitude. Variation in S. stachydifolia floral traits did not follow any evident association with bioclimatic factors, suggesting that populations may have diverged as the product of historical isolation on mountaintops. We suggest that differences among populations point to incipient speciation and an ongoing pollinator shift.

RNA processing and degradation mechanisms shaping the mitochondrial transcriptome of budding yeasts.

Yeast mitochondrial genes are expressed as polycistronic transcription units that contain RNAs from different classes and show great evolutionary variability. The promoters are simple, and transcriptional control is rudimentary. Posttranscriptional mechanisms involving RNA maturation, stability, and degradation are thus the main force shaping the transcriptome and determining the expression levels of individual genes. Primary transcripts are fragmented by tRNA excision by RNase P and tRNase Z, additional processing events occur at the dodecamer site at the 3' end of protein-coding sequences. groups I and II introns are excised in a self-splicing reaction that is supported by protein splicing factors encoded by the nuclear genes, or by the introns themselves. The 3'-to-5' exoribonucleolytic complex called mtEXO is the main RNA degradation activity involved in RNA turnover and processing, supported by an auxiliary 5'-to-3' exoribonuclease Pet127p. tRNAs and, to a lesser extent, rRNAs undergo several different base modifications. This complex gene expression system relies on the coordinated action of mitochondrial and nuclear genes and undergoes rapid evolution, contributing to speciation events. Moving beyond the classical model yeast Saccharomyces cerevisiae to other budding yeasts should provide important insights into the coevolution of both genomes that constitute the eukaryotic genetic system.

How Important Is Budding Speciation for Comparative Studies?

The acknowledgment of evolutionary dependence among species has fundamentally changed how we ask biological questions. Phylogenetic models became the standard approach for studies with 3 or more lineages, in particular those using extant species. Most phylogenetic comparative methods (PCMs) translate relatedness into covariance, meaning that evolutionary changes before lineages split should be interpreted together whereas after the split lineages are expected to change independently. This clever realization has shaped decades of research. Here, we discuss one element of the comparative method often ignored or assumed as unimportant: if nodes of a phylogeny represent the dissolution of the ancestral lineage into two new ones or if the ancestral lineage can survive speciation events (i.e., budding). Budding speciation is often reported in paleontological studies, due to the nature of the evidence for budding in the fossil record, but it is surprisingly absent in comparative methods. Here, we show that many PCMs assume that divergence happens as a symmetric split, even if these methods do not explicitly mention this assumption. We discuss the properties of trait evolution models for continuous and discrete traits and their adequacy under a scenario of budding speciation. We discuss the effects of budding speciation under a series of plausible evolutionary scenarios and show when and how these can influence our estimates. We also propose that long-lived lineages that have survived through a series of budding speciation events and given birth to multiple new lineages can produce evolutionary patterns that challenge our intuition about the most parsimonious history of trait changes in a clade. We hope our discussion can help bridge comparative approaches in paleontology and neontology as well as foster awareness about the assumptions we make when we use phylogenetic trees.

DrosOMA: the Drosophila Orthologous Matrix browser

Background: Comparative genomic analyses to delineate gene evolutionary histories inform the understanding of organismal biology by characterising gene and gene family origins, trajectories, and dynamics, as well as enabling the tracing of speciation, duplication, and loss events, and facilitating the transfer of gene functional information across species. Genomic data are available for an increasing number of species from the genus Drosophila, however, a dedicated resource exploiting these data to provide the research community with browsable results from genus-wide orthology delineation has been lacking. Methods: Using the OMA Orthologous Matrix orthology inference approach and browser deployment framework, we catalogued orthologues across a selected set of Drosophila species with high-quality annotated genomes. We developed and deployed a dedicated instance of the OMA browser to facilitate intuitive exploration, visualisation, and downloading of the genus-wide orthology delineation results. Results: DrosOMA - the Drosophila Orthologous Matrix browser, accessible from https://drosoma.dcsr.unil.ch/ - presents the results of orthology delineation for 36 drosophilids from across the genus and four outgroup dipterans. It enables querying and browsing of the orthology data through a feature-rich web interface, with gene-view, orthologous group-view, and genome-view pages, including comprehensive gene name and identifier cross-references together with available functional annotations and protein domain architectures, as well as tools to visualise local and global synteny conservation. Conclusions: The DrosOMA browser demonstrates the deployability of the OMA browser framework for building user-friendly orthology databases with dense sampling of a selected taxonomic group. It provides the Drosophila research community with a tailored resource of browsable results from genus-wide orthology delineation.

An economic model and evidence of the evolution of human intelligence in the Middle Pleistocene: Climate change and assortative mating.

A main objective of this paper is to provide the first model of how climate change, working through sexual selection, could have led to dramatic increases in hominin brain size, and presumably intelligence, in the Middle Pleistocene. The model is built using core elements from the field of family economics, including assortative mating and specialization and complementarities between mates. The main assumptions are that family public goods (e.g., conversation, shelter, fire) were particularly cognitively intensive to produce and became increasingly important for child survival during glacial phases. Intermediate climates (e.g., not the depths of severe glacial phases) create the largest gains from specialization, encouraging negative assortative mating. In contrast, severe glacial phases encourage positive assortative mating because of the rising importance of family public goods. One testable hypothesis is that absence of severe glacial phases should have led to stasis in brain size. Two other testable hypotheses are that severe glacial phases should have led to speciation events, as well as increases in brain size. The evidence shows that there was a million-year stasis in cranial size prior to the start of the severe glacial phases. This stasis is broken by a speciation event (Homo heidelbergensis), with the oldest fossil evidence dated near the close of the first severe glacial phase. In the next 300 kyr, there are two additional severe glacial phases, accompanied by considerable increases in cranial capacity. The last speciation event is Homo sapiens, with the earliest fossils dated near the end of the last of these two glacial phases.

Sexual signal evolution and patterns of assortative mating across an intraspecific contact zone.

Contact zones provide important insights into the evolutionary processes that underlie lineage divergence and speciation. Here, we use a contact zone to ascertain speciation potential in the red-eyed treefrog (Agalychnis callidryas), a brightly coloured and polymorphic frog that exhibits unusually high levels of intraspecific variation. Populations of A. callidryas differ in a number of traits, several of which are known sexual signals that mediate premating reproductive isolation in allopatric populations. Along the Caribbean coast of Costa Rica, a ~100 km contact zone, situated between two phenotypically and genetically divergent parent populations, contains multiple colour pattern phenotypes and late-generation hybrids. This contact zone provides the opportunity to examine processes that are important in the earliest stages of lineage divergence. We performed analyses of colour pattern variation in five contact zone sites and six parental sites and found complex, continuous colour variation along the contact zone. We found discordance between the geographic distribution of colour pattern and previously described genomic population structure. We then used a parental site and contact zone site to measure assortative mating and directional selection from naturally-occurring amplectant mating pairs. We found assortative mating in a parental population, but no assortative mating in the contact zone. Furthermore, we uncovered evidence of directional preference towards the adjacent parental phenotype in the contact zone population, but no directional preference in the parent population. Combined, these data provide insights into potential dynamics at the contact zone borders and indicate that incipient speciation between parent populations will be slowed.

Introgression between highly divergent fungal sister species.

To understand how species evolve and adapt to changing environments, it is important to study gene flow and introgression due to their influence on speciation and radiation events. Here, we apply a novel experimental system for investigating these mechanisms using natural populations. The system is based on two fungal sister species with morphological and ecological similarities occurring in overlapping habitats. We examined introgression between these species by conducting whole genome sequencing of individuals from populations in North America and Europe. We assessed genome-wide nucleotide divergence and performed crossing experiments to study reproductive barriers. We further used ABBA-BABA statistics together with a network analysis to investigate introgression, and conducted demographic modelling to gain insight into divergence times and introgression events. The results revealed that the species are highly divergent and incompatible in vitro. Despite this, small regions of introgression were scattered throughout the genomes and one introgression event likely involves a ghost population (extant or extinct). This study demonstrates that introgression can be found among divergent species and that population histories can be studied without collections of all the populations involved. Moreover, the experimental system is shown to be a useful tool for research on reproductive isolation in natural populations.

A 14th century CE Brucella melitensis genome and the recent expansion of the Western Mediterranean clade.

Brucellosis is a disease caused by the bacterium Brucella and typically transmitted through contact with infected ruminants. It is one of the most common chronic zoonotic diseases and of particular interest to public health agencies. Despite its well-known transmission history and characteristic symptoms, we lack a more complete understanding of the evolutionary history of its best-known species-Brucella melitensis. To address this knowledge gap we fortuitously found, sequenced and assembled a high-quality ancient B. melitensis draft genome from the kidney stone of a 14th-century Italian friar. The ancient strain contained fewer core genes than modern B. melitensis isolates, carried a complete complement of virulence genes, and did not contain any indication of significant antimicrobial resistances. The ancient B. melitensis genome fell as a basal sister lineage to a subgroup of B. melitensis strains within the Western Mediterranean phylogenetic group, with a short branch length indicative of its earlier sampling time, along with a similar gene content. By calibrating the molecular clock we suggest that the speciation event between B. melitensis and B. abortus is contemporaneous with the estimated time frame for the domestication of both sheep and goats. These results confirm the existence of the Western Mediterranean clade as a separate group in the 14th CE and suggest that its divergence was due to human and ruminant co-migration.

The meso-octoploid Heliophila variabilis genome sheds a new light on the impact of polyploidization and diploidization on the diversity of the Cape flora.

Although the South African Cape flora is one of the most remarkable biodiversity hotspots, its high diversity has not been associated with polyploidy. Here, we report the chromosome-scale genome assembly of an ephemeral cruciferous species Heliophila variabilis (~334 Mb, n = 11) adapted to South African semiarid biomes. Two pairs of differently fractionated subgenomes suggest an allo-octoploid origin of the genome at least 12 million years ago. The ancestral octoploid Heliophila genome (2n = 8x = ~60) has probably originated through hybridization between two allotetraploids (2n = 4x = ~30) formed by distant, intertribal, hybridization. Rediploidization of the ancestral genome was marked by extensive reorganization of parental subgenomes, genome downsizing, and speciation events in the genus Heliophila. We found evidence for loss-of-function changes in genes associated with leaf development and early flowering, and over-retention and sub/neofunctionalization of genes involved in pathogen response and chemical defense. The genomic resources of H. variabilis will help elucidate the role of polyploidization and genome diploidization in plant adaptation to hot arid environments and origin of the Cape flora. The sequenced H. variabilis represents the first chromosome-scale genome assembly of a meso-octoploid representative of the mustard family.

Diversification within Lycianthes moziniana (Capsiceae, Solanaceae)

Background: Lycianthes moziniana (Capsiceae, Solanaceae) is an endemic and widespread species in Mexico. Morphological and molecular evidence suggested three varieties (L. moziniana var. margaretiana, L. moziniana var. moziniana and L. moziniana var. oaxacana).
 Hypotheses: Lycianthes moziniana is integrated by differentiated lineages corresponding to the three varieties identified.
 Studied species: Lycianthes moziniana (Dunal) Bitter.
 Study sites and dates: Mexico from 2017 to 2021.
 Methods: We measured 11 morphological characters based on 207 herbarium specimens. Discriminant Canonical Analysis (DCA), Mahalanobis Square Distance (MD) and Canonical Classificatory Analysis (CCA) were used to uncover the differences among varieties. For geographic and climatic preferences and divergence, we used 288 records and four climatic layers.
 Results: Two canonical functions explained 100 % of the morphological variation and seven characters had the highest discriminatory power. In addition, MD was statistically significant. Meanwhile, the CCA recovered three groups at 77 %. The morphological evidence demonstrated the distinctiveness of L. moziniana var. moziniana. In contrast, L. moziniana var. margaretiana and L. moziniana var. oaxacana were morphologically similar. The identity test showed significant differences among Ecological Niche Models (ENMs). The evidence indicates geographic and climatic isolation among the varieties. Lycianthes moziniana var. moziniana is widespread and has intermediate overlap with the other two varieties. Lycianthes moziniana var. margaretiana and L. moziniana var. oaxacana were isolated in different biogeographical provinces and showed the lowest overlap.
 Conclusions: Morphological and geographic data indicates incipient speciation is occurring.

Phylotranscriptomic discordance is best explained by incomplete lineage sorting within Allium subgenus Cyathophora and thus hemiplasy accounts for interspecific trait transition

The transition of traits between genetically related lineages is a fascinating topic that provides clues to understanding the drivers of speciation and diversification. Much can be learned about this process from phylogeny-based trait evolution. However, such inference is often plagued by genome-wide gene-tree discordance (GTD), mostly due to incomplete lineage sorting (ILS) and/or introgressive hybridization, especially when the genes underlying the traits appear discordant. Here, by collecting transcriptomes, whole chloroplast genomes (cpDNA), and population genetic datasets, we used the coalescent model to turn GTD into a source of information for ILS and employed hemiplasy to explain specific cases of apparent “phylogenetic discordance” between different morphological traits and probable species phylogeny in the Allium subg. Cyathophora. Both concatenation and coalescence methods consistently showed the same phylogenetic topology for species tree inference based on single-copy genes (SCGs), as supported by the KS distribution. However, GTD was high across the genomes of subg. Cyathophora: ∼27%–38.9% of the SCG trees were in conflict with the species tree. Plasmid and nuclear incongruence was also present. Our coalescent simulations indicated that such GTD was mainly a product of ILS. Our hemiplasy risk factor calculations supported that random fixation of ancient polymorphisms in different populations during successive speciation events along the subg. Cyathophora phylogeny may have caused the character transition, as well as the anomalous cpDNA tree. Our study exemplifies how phylogenetic noise can be transformed into evolutionary information for understanding character state transitions along species phylogenies.

Rearranging and completing the puzzle: Phylogenomic analysis of bark beetles Dendroctonus reveals new hypotheses about genus diversification

Studies carried out on bark beetles within Dendroctonus have been extensive and revealed diverse information in different areas of their natural history, taxonomy, evolution, and interactions, among others. Despite these efforts, phylogenetic hypotheses have remained obscured mainly due to limited information analyzed (taxonomic, gene sampling, or both) in studies focused on obtaining evolutionary hypotheses for this genus. With the aim of filling these gaps in the evolutionary history for Dendroctonus, we analyzed ∼1800 loci mapped to a reference genome obtained for 20 of the 21 species recognized to date, minimizing the impact of missing information and improving the assumption of orthology in a phylogenomic framework. We obtained congruent phylogenetic topologies from two phylogenomic inference strategies: loci concatenation (ML framework) and a multispecies coalescent model (MSC) through the analysis of site pattern frequencies (SNPs). Dendroctonus is composed of two major clades (A and B), each containing five and four subclades, respectively. According to our divergence dating analysis, the MRCA for Dendroctonus dates back to the early Eocene, while the MRCA for each major clade diverged in the mid-Eocene. Interestingly, most of the speciation events of extant species occurred during the Miocene, which could be correlated with the diversification of pine trees (Pinus). The MRCA for Dendroctonus inhabited large regions of North America, with all ancestors and descendants of clade A having diversified within this region. The Mexican Transition Zone is important in the diversification processes for the majority of clade A species. For clade B, we identified two important colonization events to the Old World from America: the first in the early Oligocene from the Arctic to Asia (via Beringia), and the second during the Miocene from the Arctic-Western-Alleghany region to Europe and Siberia (also via Beringia). Our genomic analyses also supported the existence of hidden structured lineages within the frontalis complex, and also that D. beckeri represent a lineage independent from D. valens, as previously suggested. The information presented here updates the knowledge concerning the diversification of a genus with remarkable ecological and economic importance.

Crowd-sourced observations of a polyphagous moth reveal evidence of allochronic speciation varying along a latitudinal gradient.

Allochronic speciation, where reproductive isolation between populations of a species is facilitated by a difference in reproductive timing, depends on abiotic factors such as seasonality and biotic factors such as diapause intensity. These factors are strongly influenced by latitudinal trends in climate, so we hypothesized that there is a relationship between latitude and divergence among populations separated by life history timing. Hyphantria cunea (the fall webworm), a lepidopteran defoliator with red and black colour morphs, is hypothesized to be experiencing an incipient allochronic speciation. However, given their broad geographic range, the strength of allochronic speciation may vary across latitude. We annotated >11,000 crowd-sourced observations of fall webworm to model geographic distribution, phenology, and differences in colour phenotype between morphs across North America. We found that red and black morph life history timing differs across North America, and the phenology of morphs diverges more in warmer climates at lower latitudes. We also found some evidence that the colour phenotype of morphs also diverges at lower latitudes, suggesting reduced gene flow between colour morphs. Our results demonstrate that seasonality in lower latitudes may increase the strength of allochronic speciation in insects, and that the strength of sympatric speciation can vary along a latitudinal gradient. This has implications for our understanding of broad-scale speciation events and trends in global biodiversity.

COI barcoding provides reliable species identification and pinpoints cryptic diversity in Western Palearctic amphibians

Abstract Assembling DNA barcode reference libraries for various taxonomic groups allows researchers to use metabarcoding or environmental DNA approaches to gain a rapid understanding of diversity in given environments. However, our ability to use reference libraries depends on how accurately DNA barcodes are able to recover taxonomic boundaries and identify species, which is rarely considered. We constructed an extensive COI barcoding library for amphibians of the Western Palearctic and successfully recovered barcodes from 60 urodele and 73 anuran species (representing 94% and 98% of the nominal anuran and urodele species in the Western Palearctic, respectively), covering the intraspecific diversity of the majority of species in this region. We tested the effectiveness of our assembled DNA barcode dataset for species identification using barcoding gap, efficiency analyses, and two phylogenetic species delimitation methods. We obtained DNA barcodes for 1251 specimens (691 anurans and 560 urodeles) with a high success rate (92-96%) of species identification. The absence of a barcoding gap in a number of samples was linked to species misidentifications, which suggest incipient speciation or cryptic diversity, or previously described mitochondrial introgression events. The phylogenetic species delimitation methods resulted in substantial oversplitting of currently accepted taxonomy. This COI barcoding library provides an almost complete and reliable reference library for Western Palearctic amphibians. We highlight the importance of generating comprehensive and well curated reference libraries that include intra- and interspecific genetic variability and the need of detailed taxonomic revision when ambiguous or incorrect DNA barcodes exist.

Common juniper, an overlooked conifer with high invasion potential in protected areas of Patagonia

The benefits of early detection of biological invasions are widely recognized, especially for protected areas (PAs). However, research on incipient invasive plant species is scarce compared to species with a recognized history of invasion. Here, we characterized the invasion status of the non-native conifer Juniperus communis in PAs and interface areas of Andean Patagonia, Argentina. We mapped its distribution and described both the invasion and the environments this species inhabits through field studies, a literature review, and a citizen science initiative. We also modeled the species’ potential distribution by comparing the climatic characteristics of its native range with those of the introduced ranges studied. The results show that J. communis is now widely distributed in the region, occurring naturally in diverse habitats, and frequently within and close to PAs. This species can be considered an incipient invader with a high potential for expansion in its regional distribution range, largely due to its high reproductive potential and the high habitat suitability of this environment. Early detection of a plant invasion affords a valuable opportunity to inform citizens of the potential risks to high conservation value ecosystems before the invader is perceived as a natural component of the landscape.