Mangrove forests are ecologically important but globally threatened intertidal plant communities. Effective mangrove conservation requires the determination of species identity, management units, and genetic structure. Here, we investigate the genetic distinctiveness and genetic structure of an iconic but yet taxonomically confusing species complex Rhizophora mucronata and R. stylosa across their distributional range, by employing a suite of 20 informative nuclear SSR markers. Our results demonstrated the general genetic distinctiveness of R. mucronata and R. stylosa, and potential hybridization or introgression between them. We investigated the population genetics of each species without the putative hybrids, and found strong genetic structure between oceanic regions in both R. mucronata and R. stylosa. In R. mucronata, a strong divergence was detected between populations from the Indian Ocean region (Indian Ocean and Andaman Sea) and the Pacific Ocean region (Malacca Strait, South China Sea and Northwest Pacific Ocean). In R. stylosa, the genetic break was located more eastward, between populations from South and East China Sea and populations from the Southwest Pacific Ocean. The location of these genetic breaks coincided with the boundaries of oceanic currents, thus suggesting that oceanic circulation patterns might have acted as a cryptic barrier to gene flow. Our findings have important implications on the conservation of mangroves, especially relating to replanting efforts and the definition of evolutionary significant units in Rhizophora species. We outlined the genetic structure and identified geographical areas that require further investigations for both R. mucronata and R. stylosa. These results serve as the foundation for the conservation genetics of R. mucronata and R. stylosa and highlighted the need to recognize the genetic distinctiveness of closely-related species, determine their respective genetic structure, and avoid artificially promoting hybridization in mangrove restoration programmes.
The genus Fritillaria has attracted great attention because of its medicinal and ornamental values.At least three reasons, including the accurate discrimination between various Fritillaria species, protection and sustainable development of rare Fritillaria resources as well as understanding of relationship of some perplexing species, have prompted phylogenetic analyses and development of molecular markers for Fritillaria species.Here we determined the complete chloroplast (CP) genomes for F. unibracteata, F. przewalskii, F. delavayi, and F. sinica through Illumina sequencing, followed by de novo assembly.The lengths of the genomes ranged from 151,076 in F. unibracteata to 152,043 in F.przewalskii.Those CP genomes displayed a typical quadripartite structure, all including a pair of inverted repeats (26,078 to 26,355 bp) separated by the large single-copy (81,383 to 81,804 bp) and small single-copy (17,537 to 17,569 bp) regions.Fritillaria przewalskii, F. delavayi, and F. sinica equivalently encoded 133 unique genes consisting of 38 transfer RNA genes, 8 ribosomal RNA genes, and 87 protein coding genes, whereas F. unibracteata contained 132 unique genes due to absence of the rps16 gene.Subsequently, comparative analysis of the complete CP genomes revealed that ycf1, trnL, trnF, ndhD, trnN-trnR, trnE-trnT, trnN, psbM-trnD, atpI, and rps19 to be useful molecular markers in taxonomic studies owning to their interspecies variations.Based on the comprehensive CP genome data collected from 53 species in Fritillaria and Lilium genera, a phylogenomic study was carried out with three Cardiocrinum species and five Amana species as outgroups.The results of the phylogenetic analysis showed that Fritillaria was a sister to Lilium, and the interspecies relationships within subgenus Fritillaria were well resolved.Furthermore, phylogenetic analysis based on the CP genome was proved to be a promising method in selecting potential novel medicinal resources to substitute current medicinal species that are on the verge of extinction.
Protected areas (PAs) are key tools to prevent extinction and preserve ecosystem functions. As countries reiterated their commitment to expand the reach of PAs by up to 30 % by 2030, stronger purpose and pertinence in the establishment of PAs is needed to ensure effective conservation. In this study, we used Dipterocarpaceae as a proxy for threatened and ecologically important trees to determine the role of PAs in tree conservation and the potential shortfalls at a global scale. We quantified the overlap between the geo-referenced occurrence data of 433 Dipterocarpaceae species and the distribution of global PAs, followed by a conservation gap analysis on Borneo, the center of diversity of the family. We found that while Southeast Asia is the hotspot for species diversity and threat to Dipterocarpaceae, a high proportion of threatened species were found at the range edges of Dipterocarpaceae. Half of all the countries with Dipterocarpaceae met the Aichi Target 11 of designating at least 17 % of their land area as PAs, and most had <10 % of their total number of PAs being relevant to Dipterocarpaceae conservation. Our conservation gap analysis demonstrated that only 5.02 % of the total area of habitat (AOH) of endemic and Critically Endangered dipterocarps was formally protected, while 18.6 % of the total AOH was included in the Heart of Borneo complex. Our data highlights the need for a more effective global conservation gap analysis for threatened trees that could inform area-based conservation post-2020.
Sonneratia alba Sm. is one of the most widely distributed mangrove species worldwide. In this study, the whole chloroplast genome of S. alba was assembled for the first time not only in Sonneratia, but also for a member of the mangrove plant community. The total chloroplast genome was 153,061 bp in length, with a large single copy (LSC) region of 87,226 bp and a small single copy (SSC) region of 18,033 bp, separated by two inverted repeats (IRs) regions of 23,901 bp. The overall GC content was 37.3%, and 43.1%, 35.4%, and 31.1% in the IRs, LSC, and SSC regions, respectively. It contained 106 genes, including 79 coding genes, 24 tRNA genes, and four rRNA genes. A phylogenetic analysis confirmed that S. alba was clustered with Trapa maximowiczii within the family Lythraceae.
Abstract Over the past 50 years, Tropical East Asia has lost more biodiversity than any tropical region. Tropical East Asia is a megadiverse region with an acute taxonomic impediment. DNA barcodes are short standardized DNA sequences used for taxonomic purposes and have the potential to lessen the challenges of biodiversity inventory and assessments in regions where they are most needed. We reviewed DNA barcoding efforts in Tropical East Asia relative to other tropical regions. We suggest DNA barcodes (or metabarcodes from next‐generation sequencers) may be especially useful for characterizing and connecting species‐level biodiversity units in inventories encompassing taxa lacking formal description (particularly arthropods) and in large‐scale, minimal‐impact approaches to vertebrate monitoring and population assessments through secondary sources of DNA (invertebrate derived DNA and environmental DNA). We suggest interest and capacity for DNA barcoding are slowly growing in Tropical East Asia, particularly among the younger generation of researchers who can connect with the barcoding analogy and understand the need for new approaches to the conservation challenges being faced.
●Chilling restrains the distribution of mangroves. We tested whether foliar phosphorus (P) fractions and gene expression are associated with cold tolerance in mangrove species.●We exposed seedlings of six mangrove populations from different latitudes to favorable, chilling and recovery treatments, and measured their foliar P concentrations and fractions, photochemistry, night-time respiration, and gene expression. ●A Kandelia obovata (26.45ºN; KO) population completely and a Bruguiera gymnorhiza (21.50ºN; BGG) population partially (30%) survived chilling. Avicennia marina (24.29ºN), and other B. gymnorhiza (26.66ºN, 24.40ºN and 19.62ºN) populations died after chilling. Photosystems of KO and photosystem I of BGG were least injured. Following chilling, leaf P fractions, except nucleic acid P in three populations declined, and photoinhibition and night-time respiration increased in all populations, with the greatest impact in B. gymnorhiza. Leaf nucleic acid P was positively correlated with photochemical efficiency during recovery and night-time respiration across populations for each treatment.●Relatively high concentrations of nucleic acid P and metabolite P were associated with stronger chilling tolerance in K. obovata. Bruguiera gymnorhiza exhibited relatively low concentrations of organic P in favorable and chilling conditions, but its partially survived population showed stronger compensation in nucleic acid P and Pi concentrations and gene expression during recovery.
Tyrant-flycatchers (Tyrannidae) are a taxonomically confusing bird group containing a large degree of cryptic diversity that has only recently begun to be unraveled through the application of acoustic and molecular methods. We investigated all three subspecies of the Lesser Elaenia, Elaenia chiriquensis Lawrence, across their range using sound recordings as well as nuclear and mitochondrial markers. We show that two of the three subspecies, the nominate race from southern Central America and the widespread South American subspecies E. c. albivertex Pelzeln, have undergone very low levels of vocal and molecular differentiation across their fragmented range. In contrast, the isolated taxon E. c. brachyptera Berlepsch, endemic to the western and also, as recently shown, eastern slopes of the northern Andes, is phylogenetically and vocally distinct from other Lesser Elaenias, indicating that it constitutes a separate biological species.
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