In and out of Madagascar : dispersal to peripheral islands, insular speciation and diversification of Indian Ocean daisy trees (Psiadia, Asteraceae)

This study was supported by the European Union’s HOTSPOTS Training Network (MEST-2005-020561)Madagascar is surrounded by archipelagos varying widely in origin, age and structure. Although small and geologically young, these archipelagos have accumulated disproportionate numbers of unique lineages in comparison to Madagascar, highlighting the role of waif-dispersal and rapid in situ diversification processes in generating endemic biodiversity. We reconstruct the evolutionary and biogeographical history of the genus Psiadia (Asteraceae), a plant genus with near equal numbers of species in Madagascar and surrounding islands. Analyzing patterns and processes of diversification, we explain species accumulation on peripheral islands and aim to offer new insights on the origin and potential causes for diversification in the Madagascar and Indian Ocean Islands biodiversity hotspot. Our results provide support for an African origin of the group, with strong support for non-monophyly. Colonization of the Mascarenes took place by two evolutionary distinct lineages from Madagascar, via two independent dispersal events, each unique for their spatial and temporal properties. Significant shifts in diversification rate followed regional expansion, resulting in co-occurring and phenotypically convergent species on high-elevation volcanic slopes. Like other endemic island lineages, Psiadia have been highly successful in dispersing to and radiating on isolated oceanic islands, typified by high habitat diversity and dynamic ecosystems fuelled by continued geological activity. Results stress the important biogeographical role for Rodrigues in serving as an outlying stepping stone from which regional colonization took place. We discuss how isolated volcanic islands contribute to regional diversity by generating substantial numbers of endemic species on short temporal scales. Factors pertaining to the mode and tempo of archipelago formation and its geographical isolation strongly govern evolutionary pathways available for species diversification, and the potential for successful diversification of dispersed lineages, therefore, appears highly dependent on the timing of arrival, as habitat and resource properties change dramatically over the course of oceanic island evolution.Publisher PDFPeer reviewe

Chromosome‐level reference genome of the soursop (Annona muricata) : a new resource for Magnoliid research and tropical pomology

The flowering plant family Annonaceae includes important commercially grown tropical crops, but development of promising species is hindered by a lack of genomic resources to build breeding programs. Annonaceae are part of the magnoliids, an ancient lineage of angiosperms for which evolutionary relationships with other major clades remain unclear. To provide resources to breeders and evolutionary researchers, we report a chromosome-level genome assembly of the soursop (Annona muricata). We assembled the genome using 444.32 Gb of DNA sequences (676x sequencing depth) from PacBio and Illumina short-reads, in combination with 10x Genomics and Bionano data (v1). A total of 949 scaffolds were assembled to a final size of 656.77 Mb, with a scaffold N50 of 3.43 Mb (v1), and then further improved to seven pseudo-chromosomes using Hi-C sequencing data (v2; scaffold N50: 93.2 Mb, total size in chromosomes: 639.6 Mb). Heterozygosity was very low (0.06%), while repeat sequences accounted for 54.87% of the genome, and 23,375 protein-coding genes with an average of 4.79 exons per gene were annotated using de novo, RNA-seq and homology-based approaches. Reconstruction of the historical population size showed a slow continuous contraction, probably related to Cenozoic climate changes. The soursop is the first genome assembled in Annonaceae, supporting further studies of floral evolution in magnoliids, providing an essential resource for delineating relationships of ancient angiosperm lineages. Both genome-assisted improvement and conservation efforts will be strengthened by the availability of the soursop genome. As a community resource, this assembly will further strengthen the role of Annonaceae as model species for research on the ecology, evolution and domestication potential of tropical species in pomology and agroforestry

Chromosome-level reference genome of the soursop (Annona muricata): A new resource for Magnoliid research and tropical pomology

The flowering plant family Annonaceae includes important commercially grown tropical crops, but development of promising species is hindered by a lack of genomic resources to build breeding programs. Annonaceae are part of the magnoliids, an ancient lineage of angiosperms for which evolutionary relationships with other major clades remain unclear. To provide resources to breeders and evolutionary researchers, we report a chromosome‐level genome assembly of the soursop (Annona muricata). We assembled the genome using 444.32 Gb of DNA sequences (676× sequencing depth) from PacBio and Illumina short‐reads, in combination with 10× Genomics and Bionano data (v1). A total of 949 scaffolds were assembled to a final size of 656.77 Mb, with a scaffold N50 of 3.43 Mb (v1), and then further improved to seven pseudo‐chromosomes using Hi‐C sequencing data (v2; scaffold N50: 93.2 Mb, total size in chromosomes: 639.6 Mb). Heterozygosity was very low (0.06%), while repeat sequences accounted for 54.87% of the genome, and 23,375 protein‐coding genes with an average of 4.79 exons per gene were annotated using de novo, RNA‐seq and homology‐based approaches. Reconstruction of the historical population size showed a slow continuous contraction, probably related to Cenozoic climate changes. The soursop is the first genome assembled in Annonaceae, supporting further studies of floral evolution in magnoliids, providing an essential resource for delineating relationships of ancient angiosperm lineages. Both genome‐assisted improvement and conservation efforts will be strengthened by the availability of the soursop genome. As a community resource, this assembly will further strengthen the role of Annonaceae as model species for research on the ecology, evolution and domestication potential of tropical species in pomology and agroforestry

Syzygium (Myrtaceae): Monographing a taxonomic giant via 22 coordinated regional revisions

Syzygium Gaertn. is the largest woody genus of flowering plants in the world. Unpublished but extensive recent herbarium surveys suggest 1200‒1800 species distributed throughout the Old-World tropics and subtropics (Table 1). Until recently, Syzygium exemplified a recurring taxonomic impediment among megadiverse genera, wherein few taxonomists worked on the group in any sustained manner, a majority of the herbarium specimens remained undetermined or misidentified, few if any attempts were made to look at the genus globally and limited or no molecular studies were available to provide a predictive phylogenetic context of the genus. The situation with Syzygium has slowly begun to change as allied genera have been absorbed into the genus (Biffin et al., 2006; Craven & Biffin, 2010), and predictive phylogenetically based infrageneric classifications are emerging. Taxonomic outputs on Syzygium also have been increasing across its range with the description of new species, resolution of nomenclatural and typification issues, and some regional revisions being initiated or updated. However, virtually all regional treatments (which some areas lack) need urgent revision because they are severely outdated, have limited molecular sampling and are error-ridden. We are coordinating a genus-wide taxonomic update of Syzygium through a series of 22 regional revisions, including 9 in the Flora Malesiana region (Figure 1). Each treatment will include a phylogenetic framework with species descriptions, type information, synonymy, distributions, ecological notes, and keys. Field images (Figure 2) and/or line drawings will be included with the goal of every species being illustrated. This working group has been formed to encourage a coordinated effort to document this unwieldy taxonomic giant and regional botanists working on the group are encouraged to be involved. A robust taxonomy of the genus is a prerequisite for testing the many complex questions about evolution and ecology that Syzygium could help address

Extending our scientific reach in arboreal ecosystems for research and management

The arboreal ecosystem is vitally important to global and local biogeochemical processes, the maintenance of biodiversity in natural systems, and human health in urban environments. The ability to collect samples, observations, and data to conduct meaningful scientific research is similarly vital. The primary methods and modes of access remain limited and difficult. In an online survey, canopy researchers (n = 219) reported a range of challenges in obtaining adequate samples, including ∼10% who found it impossible to procure what they needed. Currently, these samples are collected using a combination of four primary methods: (1) sampling from the ground; (2) tree climbing; (3) constructing fixed infrastructure; and (4) using mobile aerial platforms, primarily rotorcraft drones. An important distinction between instantaneous and continuous sampling was identified, allowing more targeted engineering and development strategies. The combination of methods for sampling the arboreal ecosystem provides a range of possibilities and opportunities, particularly in the context of the rapid development of robotics and other engineering advances. In this study, we aim to identify the strategies that would provide the benefits to a broad range of scientists, arborists, and professional climbers and facilitate basic discovery and applied management. Priorities for advancing these efforts are (1) to expand participation, both geographically and professionally; (2) to define 2–3 common needs across the community; (3) to form and motivate focal teams of biologists, tree professionals, and engineers in the development of solutions to these needs; and (4) to establish multidisciplinary communication platforms to share information about innovations and opportunities for studying arboreal ecosystems

DNA_sequences_Dipterocarpace

GFF files with annotations of the Dipterocarpaceae playtimes and NRC used in the analyse

Data from: Exploring evolution and diversity of Chinese Dipterocarpaceae using next-generation sequencing

Tropical forests, a key-category of land ecosystems, are faced with the world’s highest levels of habitat conversion and associated biodiversity loss. In tropical Asia, Dipterocarpaceae are one of the economically and ecologically most important tree families, but their genomic diversity and evolution remain understudied, hampered by a lack of available genetic resources. Southern China represents the northern limit for Dipterocarpaceae, and thus changes in habitat ecology, community composition and adaptability to climatic conditions are of particular interest in this group. Phylogenomics is a tool for exploring both biodiversity and evolutionary relationships through space and time using plastome, nuclear and mitochondrial genome. We generated full plastome and Nuclear Ribosomal Cistron (NRC) data for Chinese Dipterocarpaceae species as a first step to improve our understanding of their ecology and evolutionary relationships. We generated the plastome of Dipterocarpus turbinatus, the species with the widest distribution using it as a baseline for comparisons with other taxa. Results showed low level of genomic diversity among analysed range-edge species, and different evolutionary history of the incongruent NRC and plastome data. Genomic resources provided in this study will serve as a starting point for future studies on conservation and sustainable use of these dominant forest taxa, phylogenomics and evolutionary studies

Resolving phylogenetic relationships and species delimitations in closely related gymnosperms using high-throughput NGS, Sanger sequencing and morphology

Plastid genomes have been widely applied to elucidate plant evolution at higher taxonomic levels, but have rarely been considered useful for addressing close relationships. Here, we resolve the phylogeny and taxonomy of the Chinese lianoid Gnetum clade (Gnetales), using high throughput and Sanger sequencing techniques and studies of plant morphology. Despite previous efforts, relationships among taxa and the taxonomy within the clade have remained unclear. We generated 11 plastid genomes representing one arborescent and four lianoid species. Phylogenetic analyses were conducted using (a) the entire plastid genomes and (b) the protein-coding genes only. Sequence divergence among the lianoid species was substantial, with 9345 variable sites. Four variable regions were identified, targeted and sequenced for an additional 54 specimens and analyzed together with one nuclear ribosomal marker. Results from the phylogenetic analyses corroborate G. parvifolium as sister to the remaining lianoid species and support the presence of at least five additional species in the Chinese lianoid clade: G. catasphaericum, G. formosum, G. luofuense, G. montanum and G. pendulum. Following morphological investigations, G. giganteum and G. gracilipes are included in and synonymized with G. pendulum. Gnetum hainanense is included in and synonymized with G. luofuense. Two names, G. indicum and G. cleistostachyum, remain questionable. A taxonomic revision and a key to Chinese lianoid Gnetum are presented. Internal nodes in the Chinese lianoid Gnetum clade are from the Miocene and onwards and coincide with the expansion of tropical to subtropical forests in South China, which may have facilitated speciation in the clade

ECuADOR—Easy Curation of Angiosperm Duplicated Organellar Regions, a tool for cleaning and curating plastomes assembled from next generation sequencing pipelines

Background With the rapid increase in availability of genomic resources offered by Next-Generation Sequencing (NGS) and the availability of free online genomic databases, efficient and standardized metadata curation approaches have become increasingly critical for the post-processing stages of biological data. Especially in organelle-based studies using circular chloroplast genome datasets, the assembly of the main structural regions in random order and orientation represents a major limitation in our ability to easily generate “ready-to-align” datasets for phylogenetic reconstruction, at both small and large taxonomic scales. In addition, current practices discard the most variable regions of the genomes to facilitate the alignment of the remaining coding regions. Nevertheless, no software is currently available to perform curation to such a degree, through simple detection, organization and positioning of the main plastome regions, making it a time-consuming and error-prone process. Here we introduce a fast and user friendly software ECuADOR, a Perl script specifically designed to automate the detection and reorganization of newly assembled plastomes obtained from any source available (NGS, sanger sequencing or assembler output). Methods ECuADOR uses a sliding-window approach to detect long repeated sequences in draft sequences, which then identifies the inverted repeat regions (IRs), even in case of artifactual breaks or sequencing errors and automates the rearrangement of the sequence to the widely used LSC–Irb–SSC–IRa order. This facilitates rapid post-editing steps such as creation of genome alignments, detection of variable regions, SNP detection and phylogenomic analyses. Results ECuADOR was successfully tested on plant families throughout the angiosperm phylogeny by curating 161 chloroplast datasets. ECuADOR first identified and reordered the central regions (LSC–Irb–SSC–IRa) for each dataset and then produced a new annotation for the chloroplast sequences. The process took less than 20 min with a maximum memory requirement of 150 MB and an accuracy of over 99%. Conclusions ECuADOR is the sole de novo one-step recognition and re-ordination tool that provides facilitation in the post-processing analysis of the extra nuclear genomes from NGS data. The program is available at https://github.com/BiodivGenomic/ECuADOR/

Complete chloroplast sequence of Fenerivia ghesquiereana (Annonaceae): a rare and endemic tree from Madagascar

Fenerivia ghesquiereana (Cavaco & Keraudren) R.M.K. Saunders (Annaonaceae) is a rare and endemic tree restricted to the warm tropical forests of Madagascar, a major global hotspot for biodiversity. Species in the genus are mostly restricted to a thin belt along the eastern edge of the island and remain under intense pressure due to deforestation for logging, mining and slash-and-burn agriculture (‘tavy’), despite national pledges to curb biodiversity losses and increase park protection to combat illegal logging and poaching. Here we report the complete chloroplast genome sequence of this species to support ongoing efforts to complete the (sub-)tribal classification of the family. The chloroplast sequence of F. ghesquiereana was 160,194 bp in length, including two inverted repeat regions of 26,093 bp, a large single-copy region of 89,041 bp and a small single-copy region of 18,967 bp. A total of 160 genes were annotated, of which 115 are coding, 37 are tRNA genes, and eight are rRNA genes. The overall GC content was 39%; this was higher in the IRs (43.4%) when compared to the LSC (30.7%) and the SSC (33.9%) regions. A Maximum Likelihood phylogenetic analysis with a selection of other plastomes in Annonaceae placed F. ghesquiereana as sister to Meiogyne hainanensis (Merr.) in subfamily Malmeoideae