High-resolution maps show that rubber causes substantial deforestation.

Understanding the effects of cash crop expansion on natural forest is of fundamental importance. However, for most crops there are no remotely sensed global maps1, and global deforestation impacts are estimated using models and extrapolations. Natural rubber is an example of a principal commodity for which deforestation impacts have been highly uncertain, with estimates differing more than fivefold1-4. Here we harnessed Earth observation satellite data and cloud computing5 to produce high-resolution maps of rubber (10 m pixel size) and associated deforestation (30 m pixel size) for Southeast Asia. Our maps indicate that rubber-related forest loss has been substantially underestimated in policy, by the public and in recent reports6-8. Our direct remotely sensed observations show that deforestation for rubber is at least twofold to threefold higher than suggested by figures now widely used for setting policy4. With more than 4 million hectares of forest loss for rubber since 1993 (at least 2 million hectares since 2000) and more than 1 million hectares of rubber plantations established in Key Biodiversity Areas, the effects of rubber on biodiversity and ecosystem services in Southeast Asia could be extensive. Thus, rubber deserves more attention in domestic policy, within trade agreements and in incoming due-diligence legislation.

Genetic factors predict hybrid formation in the British flora.

Natural hybridization can have a profound evolutionary impact, with consequences ranging from the extinction of rare taxa to the origin of new species. Natural hybridization is particularly common in plants; however, our understanding of the general factors that promote or prevent hybridization is hampered by the highly variable outcomes in different lineages. Here, we quantify the influence of different predictors on hybrid formation across species from an entire flora. We combine estimates of hybridization with ecological attributes and a new species-level phylogeny for over 1,100 UK flowering plant species. Our results show that genetic factors, particularly parental genetic distance, as well as phylogenetic position and ploidy, are key determinants of hybrid formation, whereas many other factors such as range overlap and genus size explain much less variation in hybrid formation. Overall, intrinsic genetic factors shape the evolutionary and ecological consequences of natural hybridization across species in a flora.

DNA barcoding identifies cryptic animal tool materials.

Some animals fashion tools or constructions out of plant materials to aid foraging, reproduction, self-maintenance, or protection. Their choice of raw materials can affect the structure and properties of the resulting artifacts, with considerable fitness consequences. Documenting animals' material preferences is challenging, however, as manufacture behavior is often difficult to observe directly, and materials may be processed so heavily that they lack identifying features. Here, we use DNA barcoding to identify, from just a few recovered tool specimens, the plant species New Caledonian crows (Corvus moneduloides) use for crafting elaborate hooked stick tools in one of our long-term study populations. The method succeeded where extensive fieldwork using an array of conventional approaches-including targeted observations, camera traps, radio-tracking, bird-mounted video cameras, and behavioral experiments with wild and temporarily captive subjects-had failed. We believe that DNA barcoding will prove useful for investigating many other tool and construction behaviors, helping to unlock significant research potential across a wide range of study systems.

Resolution, conflict and rate shifts: insights from a densely sampled plastome phylogeny for Rhododendron (Ericaceae).

BACKGROUND AND AIMS: Rhododendron is a species-rich and taxonomically challenging genus due to recent adaptive radiation and frequent hybridization. A well-resolved phylogenetic tree would help to understand the diverse history of Rhododendron in the Himalaya-Hengduan Mountains where the genus is most diverse. METHODS: We reconstructed the phylogeny based on plastid genomes with broad taxon sampling, covering 161 species representing all eight subgenera and all 12 sections, including ~45 % of the Rhododendron species native to the Himalaya-Hengduan Mountains. We compared this phylogeny with nuclear phylogenies to elucidate reticulate evolutionary events and clarify relationships at all levels within the genus. We also estimated the timing and diversification history of Rhododendron, especially the two species-rich subgenera Rhododendron and Hymenanthes that comprise >90 % of Rhododendron species in the Himalaya-Hengduan Mountains. KEY RESULTS: The full plastid dataset produced a well-resolved and supported phylogeny of Rhododendron. We identified 13 clades that were almost always monophyletic across all published phylogenies. The conflicts between nuclear and plastid phylogenies suggested strongly that reticulation events may have occurred in the deep lineage history of the genus. Within Rhododendron, subgenus Therorhodion diverged first at 56 Mya, then a burst of diversification occurred from 23.8 to 17.6 Mya, generating ten lineages among the component 12 clades of core Rhododendron. Diversification in subgenus Rhododendron accelerated c. 16.6 Mya and then became fairly continuous. Conversely, Hymenanthes diversification was slow at first, then accelerated very rapidly around 5 Mya. In the Himalaya-Hengduan Mountains, subgenus Rhododendron contained one major clade adapted to high altitudes and another to low altitudes, whereas most clades in Hymenanthes contained both low- and high-altitude species, indicating greater ecological plasticity during its diversification. CONCLUSIONS: The 13 clades proposed here may help to identify specific ancient hybridization events. This study will help to establish a stable and reliable taxonomic framework for Rhododendron, and provides insight into what drove its diversification and ecological adaption. Denser sampling of taxa, examining both organelle and nuclear genomes, is needed to better understand the divergence and diversification history of Rhododendron.

Plastid phylogenomic insights into relationships of all flowering plant families.

BACKGROUND: Flowering plants (angiosperms) are dominant components of global terrestrial ecosystems, but phylogenetic relationships at the familial level and above remain only partially resolved, greatly impeding our full understanding of their evolution and early diversification. The plastome, typically mapped as a circular genome, has been the most important molecular data source for plant phylogeny reconstruction for decades. RESULTS: Here, we assembled by far the largest plastid dataset of angiosperms, composed of 80 genes from 4792 plastomes of 4660 species in 2024 genera representing all currently recognized families. Our phylogenetic tree (PPA II) is essentially congruent with those of previous plastid phylogenomic analyses but generally provides greater clade support. In the PPA II tree, 75% of nodes at or above the ordinal level and 78% at or above the familial level were resolved with high bootstrap support (BP ≥ 90). We obtained strong support for many interordinal and interfamilial relationships that were poorly resolved previously within the core eudicots, such as Dilleniales, Saxifragales, and Vitales being resolved as successive sisters to the remaining rosids, and Santalales, Berberidopsidales, and Caryophyllales as successive sisters to the asterids. However, the placement of magnoliids, although resolved as sister to all other Mesangiospermae, is not well supported and disagrees with topologies inferred from nuclear data. Relationships among the five major clades of Mesangiospermae remain intractable despite increased sampling, probably due to an ancient rapid radiation. CONCLUSIONS: We provide the most comprehensive dataset of plastomes to date and a well-resolved phylogenetic tree, which together provide a strong foundation for future evolutionary studies of flowering plants.

A transcriptome-based resolution for a key taxonomic controversy in Cupressaceae.

Background and Aims: Rapid evolutionary divergence and reticulate evolution may result in phylogenetic relationships that are difficult to resolve using small nucleotide sequence data sets. Next-generation sequencing methods can generate larger data sets that are better suited to solving these puzzles. One major and long-standing controversy in conifers concerns generic relationships within the subfamily Cupressoideae (105 species, approx. 1/6 of all conifers) of Cupressaceae, in particular the relationship between Juniperus, Cupressus and the Hesperocyparis-Callitropsis-Xanthocyparis (HCX) clade. Here we attempt to resolve this question using transcriptome-derived data. Methods: Transcriptome sequences of 20 species from Cupressoideae were collected. Using MarkerMiner, single-copy nuclear (SCN) genes were extracted. These were applied to estimate phylogenies based on concatenated data, species trees and a phylogenetic network. We further examined the effect of alternative backbone topologies on downstream analyses, including biogeographic inference and dating analysis. Results: Based on the 73 SCN genes (>200 000 bp total alignment length) we considered, all tree-building methods lent strong support for the relationship (HCX, (Juniperus, Cupressus)); however, strongly supported conflicts among individual gene trees were also detected. Molecular dating suggests that these three lineages shared a most recent common ancestor approx. 60 million years ago (Mya), and that Juniperus and Cupressus diverged about 56 Mya. Ancestral area reconstructions (AARs) suggest an Asian origin for the entire clade, with subsequent dispersal to North America, Europe and Africa. Conclusions: Our analysis of SCN genes resolves a controversial phylogenetic relationship in the Cupressoideae, a major clade of conifers, and suggests that rapid evolutionary divergence and incomplete lineage sorting probably acted together as the source for conflicting phylogenetic inferences between gene trees and between our robust results and recently published studies. Our updated backbone topology has not substantially altered molecular dating estimates relative to previous studies; however, application of the latest AAR approaches has yielded a clearer picture of the biogeographic history of Cupressoideae.

Development of polymorphic microsatellite markers for tree peony Paeonia delavayi (Paeoniaceae) using ddRAD-seq data.

Microsatellite markers were developed for the tree peony Paeonia delavayi to investigate fine scale population genetics of this species. Using ddRAD-seq data from twenty individuals of P. delavayi, we identified 529 polymorphic microsatellite loci, of which 195 were suitable for designing microsatellite primers. Of the 120 microsatellite loci selected for validation, 20 were successfully amplified with clear peaks and displayed polymorphism. Three populations were genotyped using the 20 polymorphic microsatellites. The number of alleles per locus ranged from two to thirteen. Observed and expected heterozygosity ranged from 0 to 0.941 and 0 to 0.834 respectively. The cross-species amplification test using five individuals from a population of P. ludlowii showed that 15 of the 20 polymorphic loci were successfully amplified, and four loci showed polymorphism. Among the 22 alleles occurring in P. ludlowii across fifteen loci, eight alleles across five loci were exclusive to P. ludlowii. The results demonstrate that ddRAD-seq is an efficient method for the development of microsatellite markers for non-model organisms with large genomes. The newly developed markers will be valuable tools to investigate the genetic diversity, genetic structure, and gene flow of P. delavayi from local to regional spatial scales.

China's fight to halt tree cover loss.

China is investing immense resources for planting trees, totalling more than US$ 100 billion in the past decade alone. Every year, China reports more afforestation than the rest of the world combined. Here, we show that China's forest cover gains are highly definition-dependent. If the definition of 'forest' follows FAO criteria (including immature and temporarily unstocked areas), China has gained 434 000 km2 between 2000 and 2010. However, remotely detectable gains of vegetation that non-specialists would view as forest (tree cover higher than 5 m and minimum 50% crown cover) are an order of magnitude less (33 000 km2). Using high-resolution maps and environmental modelling, we estimate that approximately 50% of the world's forest with minimum 50% crown cover has been lost in the past approximately 10 000 years. China historically lost 1.9-2.7 million km2 (59-67%), and substantial losses continue. At the same time, most of China's afforestation investment targets environments that our model classes as unsuitable for trees. Here, gains detectable via satellite imagery are limited. Conversely, the regions where modest gains are detected are environmentally suitable but have received little afforestation investment due to conflicting land-use demands for agriculture and urbanization. This highlights the need for refined forest monitoring, and greater consideration of environmental suitability in afforestation programmes.

International Barcode of Life: Focus on big biodiversity in South Africa.

Participants in the 7th International Barcode of Life Conference (Kruger National Park, South Africa, 20-24 November 2017) share the latest findings in DNA barcoding research and its increasingly diversified applications. Here, we review prevailing trends synthesized from among 429 invited and contributed abstracts, which are collated in this open-access special issue of Genome. Hosted for the first time on the African continent, the 7th Conference places special emphasis on the evolutionary origins, biogeography, and conservation of African flora and fauna. Within Africa and elsewhere, DNA barcoding and related techniques are being increasingly used for wildlife forensics and for the validation of commercial products, such as medicinal plants and seafood species. A striking trend of the conference is the dramatic rise of studies on environmental DNA (eDNA) and on diverse uses of high-throughput sequencing techniques. Emerging techniques in these areas are opening new avenues for environmental biomonitoring, managing species-at-risk and invasive species, and revealing species interaction networks in unprecedented detail. Contributors call for the development of validated community standards for high-throughput sequence data generation and analysis, to enable the full potential of these methods to be realized for understanding and managing biodiversity on a global scale.

From barcodes to genomes: extending the concept of DNA barcoding.

DNA barcoding has had a major impact on biodiversity science. The elegant simplicity of establishing massive scale databases for a few barcode loci is continuing to change our understanding of species diversity patterns, and continues to enhance human abilities to distinguish among species. Capitalizing on the developments of next generation sequencing technologies and decreasing costs of genome sequencing, there is now the opportunity for the DNA barcoding concept to be extended to new kinds of genomic data. We illustrate the benefits and capacity to do this, and also note the constraints and barriers to overcome before it is truly scalable. We advocate a twin track approach: (i) continuation and acceleration of global efforts to build the DNA barcode reference library of life on earth using standard DNA barcodes and (ii) active development and application of extended DNA barcodes using genome skimming to augment the standard barcoding approach.

Hidden in plain view: Cryptic diversity in the emblematic Araucaria of New Caledonia.

PREMISE OF THE STUDY: Cryptic species represent a conservation challenge, because distributions and threats cannot be accurately assessed until species are recognized and defined. Cryptic species are common in diminutive and morphologically simple organisms, but are rare in charismatic and/or highly visible groups such as conifers. New Caledonia, a small island in the southern Pacific is a hotspot of diversity for the emblematic conifer genus Araucaria (Araucariaceae, Monkey Puzzle trees) where 13 of the 19 recognized species are endemic. METHODS: We sampled across the entire geographical distribution of two closely related species (Araucaria rulei and A. muelleri) and screened them for genetic variation at 12 nuclear and 14 plastid microsatellites and one plastid minisatellite; a subset of the samples was also examined using leaf morphometrics. KEY RESULTS: The genetic data show that populations of the endangered A. muelleri fall into two clearly distinct genetic groups: one corresponding to montane populations, the other corresponding to trees from lower elevation populations from around the Goro plateau. These Goro plateau populations are more closely related to A. rulei, but are sufficiently genetically and morphological distinct to warrant recognition as a new species. CONCLUSIONS: Our study shows the presence of a previously unrecognized species in this flagship group, and that A. muelleri has 30% fewer individuals than previously thought. Combined, this clarification of species diversity and distributions provides important information to aid conservation planning for New Caledonian Araucaria.

Developing the Protocol Infrastructure for DNA Sequencing Natural History Collections.

Intentionally preserved biological material in natural history collections represents a vast repository of biodiversity. Advances in laboratory and sequencing technologies have made these specimens increasingly accessible for genomic analyses, offering a window into the genetic past of species and often permitting access to information that can no longer be sampled in the wild. Due to their age, preparation and storage conditions, DNA retrieved from museum and herbarium specimens is often poor in yield, heavily fragmented and biochemically modified. This not only poses methodological challenges in recovering nucleotide sequences, but also makes such investigations susceptible to environmental and laboratory contamination. In this paper, we review the practical challenges associated with making the recovery of DNA sequence data from museum collections more routine. We first review key operational principles and issues to address, to guide the decision-making process and dialogue between researchers and curators about when and how to sample museum specimens for genomic analyses. We then outline the range of steps that can be taken to reduce the likelihood of contamination including laboratory set-ups, workflows and working practices. We finish by presenting a series of case studies, each focusing on protocol practicalities for the application of different mainstream methodologies to museum specimens including: (i) shotgun sequencing of insect mitogenomes, (ii) whole genome sequencing of insects, (iii) genome skimming to recover plant plastid genomes from herbarium specimens, (iv) target capture of multi-locus nuclear sequences from herbarium specimens, (v) RAD-sequencing of bird specimens and (vi) shotgun sequencing of ancient bovid bone samples.

AFLP markers provide insights into the evolutionary relationships and diversification of New Caledonian Araucaria species (Araucariaceae).

PREMISE OF THE STUDY: Despite its small size, New Caledonia is characterized by a very diverse flora and striking environmental gradients, which make it an ideal setting to study species diversification. Thirteen of the 19 Araucaria species are endemic to the territory and form a monophyletic group, but patterns and processes that lead to such a high species richness are largely unexplored. METHODS: We used 142 polymorphic AFLP markers and performed analyses based on Bayesian clustering algorithms, genetic distances, and cladistics on 71 samples representing all New Caledonian Araucaria species. We examined correlations between the inferred evolutionary relationships and shared morphological, ecological, or geographic parameters among species, to investigate evolutionary processes that may have driven speciation. KEY RESULTS: We showed that genetic divergence among the present New Caledonian Araucaria species is low, suggesting recent diversification rather than pre-existence on Gondwana. We identified three genetic groups that included small-leaved, large-leaved, and coastal species, but detected no association with soil preference, ecological habitat, or rainfall. The observed patterns suggested that speciation events resulted from both differential adaptation and vicariance. Last, we hypothesize that speciation is ongoing and/or there are cryptic species in some genetically (sometimes also morphologically) divergent populations. CONCLUSIONS: Further data are required to provide better resolution and understanding of the diversification of New Caledonian Araucaria species. Nevertheless, our study allowed insights into their evolutionary relationships and provides a framework for future investigations on the evolution of this emblematic group of plants in one of the world's biodiversity hotspots.

Isolation of microsatellite primers for Melampyrum sylvaticum (Orobanchaceae), an endangered plant in the United Kingdom.

PREMISE OF THE STUDY: Microsatellite markers were developed for the hemiparasitic plant Melampyrum sylvaticum to investigate the breeding system, genetic diversity, and structure of populations in the United Kingdom, Sweden, and Norway. METHODS AND RESULTS: Microsatellites were isolated from genomic DNA using an enrichment protocol. Twenty-nine loci were characterized in two individuals from each of 15 geographically disparate populations ("global"). Seven polymorphic loci were further characterized in one population ("local"). The number of alleles per locus ranged from two to 12 in the global sample and one to seven in the local sample. The expected heterozygosity ranged from 0-0.75, the observed heterozygosity from 0-0.1, and the inbreeding coefficient from 0.84-1 in the local sample. CONCLUSIONS: The results show the utility of these novel polymorphic microsatellite markers for further conservation genetic analyses. The strong deficit of heterozygosity across all loci in the local sample suggests the species may be inbreeding.

Using target capture to address conservation challenges: Population-level tracking of a globally-traded herbal medicine.

The promotion of responsible and sustainable trade in biological resources is widely proposed as one solution to mitigate current high levels of global biodiversity loss. Various molecular identification methods have been proposed as appropriate tools for monitoring global supply chains of commercialized animals and plants. Here, we demonstrate the efficacy of target capture genomic barcoding in identifying and establishing the geographic origin of samples traded as Anacyclus pyrethrum, a medicinal plant assessed as globally vulnerable in the IUCN Red List of Threatened Species. Samples collected from national and international supply chains were identified through target capture sequencing of 443 low-copy nuclear makers and compared to results derived from genome skimming of plastome and DNA barcoding of standard plastid regions and ITS. Both target capture and genome skimming provided approximately 3.4 million reads per sample, but target capture largely outperformed standard plant barcodes and entire plastid genome sequences. We were able to discern the geographical origin of Anacyclus samples collected in Moroccan, Indian and Sri Lankan markets, differentiating between plant materials originally harvested from diverse populations in Algeria and Morocco. Dropping costs of analysing samples enables the potential of target capture to routinely identify commercialized plant species and determine their geographic origin. It promises to play an important role in monitoring and regulation of plant species in trade, supporting biodiversity conservation efforts, and in ensuring that plant products are unadulterated, contributing to consumer protection.

Population genomics reveal deep divergence and strong geographical structure in gentians in the Hengduan Mountains.

Understanding the evolutionary and ecological processes driving population differentiation and speciation can provide critical insights into the formation of biodiversity. Here, we examine the link between population genetic processes and biogeographic history underlying the generation of diversity in the Hengduan Mountains (HM), a region harboring a rich and dynamic flora. We used restriction site-associated DNA sequencing to generate 1,907 single-nucleotide polymorphisms (SNPs) and four-kb of plastid sequence in species of the Gentiana hexaphylla complex (Gentianaceae). We performed genetic clustering with spatial and non-spatial models, phylogenetic reconstructions, and ancestral range estimation, with the aim of addressing the processes influencing diversification of G. hexaphylla in the HM. We find the G. hexaphylla complex is characterized by geographic genetic structure with clusters corresponding to the South, North and the central HM. Phylogenetic reconstruction and pairwise F ST analyses showed deep differentiation between Southern and Northern populations in the HM. The population in Mount Taibai exhibited the highest genetic similarity to the North HM. Ancestral range estimation indicated that the G. hexaphylla complex originated in the central HM and then diverged in the Pliocene and the Early Pleistocene, before dispersing widely, resulting in the current distinct lineages. Overall, we found deep genomic differentiation in the G. hexaphylla complex corresponds to geographic barriers to dispersal in the HM and highlights a critical role of the uplift of the Daxue Mountains and subsequent climatic fluctuations underlying diversification. The colonization of G. hexaphylla in the Mount Taibai region suggests directional dispersal between the alpine flora of the Qinling Mountains and the HM.

Testing genome skimming for species discrimination in the large and taxonomically difficult genus Rhododendron.

Standard plant DNA barcodes based on 2-3 plastid regions, and nrDNA ITS show variable levels of resolution, and fail to discriminate among species in many plant groups. Genome skimming to recover complete plastid genome sequences and nrDNA arrays has been proposed as a solution to address these resolution limitations. However, few studies have empirically tested what gains are achieved in practice. Of particular interest is whether adding substantially more plastid and nrDNA characters will lead to an increase in discriminatory power, or whether the resolution limitations of standard plant barcodes are fundamentally due to plastid genomes and nrDNA not tracking species boundaries. To address this, we used genome skimming to recover near-complete plastid genomes and nuclear ribosomal DNA from Rhododendron species and compared discrimination success with standard plant barcodes. We sampled 218 individuals representing 145 species of this species-rich and taxonomically difficult genus, focusing on the global biodiversity hotspots of the Himalaya-Hengduan Mountains. Only 33% of species were distinguished using ITS+matK+rbcL+trnH-psbA. In contrast, 55% of species were distinguished using plastid genome and nrDNA sequences. The vast majority of this increase is due to the additional plastid characters. Thus, despite previous studies showing an asymptote in discrimination success beyond 3-4 plastid regions, these results show that a demonstrable increase in discriminatory power is possible with extensive plastid genome data. However, despite these gains, many species remain unresolved, and these results also reinforce the need to access multiple unlinked nuclear loci to obtain transformative gains in species discrimination in plants.