Characterization of the complete chloroplast genome of Cycas hongheensis (Cycadaceae), an endemic species in the red river region of China.
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ABSTRACT:
SUBMITTER: Wu LX
PROVIDER: S-EPMC8635533 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Delimitating species boundaries could be of critical importance when evaluating the species' evolving process and providing guidelines for conservation genetics. Here, species delimitation was carried out on three endemic and endangered Cycas species with resembling morphology and overlapped distribution range along the Red River (Yuanjiang) in China: Cycas diananensis Z. T. Guan et G. D. Tao, Cycas parvula S. L. Yang and Cycas multiovula D. Y. Wang. A total of 137 individuals from 15 populations were genotyped by using three chloroplastic (psbA-trnH, atpI-atpH, and trnL-rps4) and two single copy nuclear (RPB1 and SmHP) DNA sequences. Basing on the carefully morphological comparison and cladistic haplotype aggregation (CHA) analysis, we propose all the populations as one species, with the rest two incorporated into C. diannanensis. Genetic diversity and structure analysis of the conflated C. diannanensis revealed this species possessed a relative lower genetic diversity than estimates of other Cycas species. The higher genetic diversity among populations and relative lower genetic diversity within populations, as well as obvious genetic differentiation among populations inferred from chloroplastic DNA (cpDNA) suggested a recent genetic loss within this protected species. Additionally, a clear genetic structure of C. diannanensis corresponding with geography was detected based on cpDNA, dividing its population ranges into "Yuanjiang-Nanhun" basin and "Ejia-Jiepai" basin groups. Demographical history analyses based on combined cpDNA and one nuclear DNA (nDNA) SmHP both showed the population size of C. diannanensis began to decrease in Quaternary glaciation with no subsequent expansion, while another nDNA RPB1 revealed a more recent sudden expansion after long-term population size contraction, suggesting its probable bottleneck events in history. Our findings offer grounded views for clarifying species boundaries of C. diannanensis when determining the conservation objectives. For operational guidelines, the downstream populations which occupy high and peculiar haplotypes should be given prior in-situ conservation. In addition, ex-situ conservation and reintroduction measures for decades of generations are supplemented for improving the population size and genetic diversity of the endemic and endangered species.
| S-EPMC4562272 | biostudies-literature
Project description:Cycas multipinnata C.J. Chen & S.Y. Yang is a cycad endemic to the Red River drainage region that occurs under evergreen forest on steep limestone slopes in Southwest China and northern Vietnam. It is listed as endangered due to habitat loss and over-collecting for the ornamental plant trade, and only several populations remain. In this study, we assess the genetic variation, population structure, and phylogeography of C. multipinnata populations to help develop strategies for the conservation of the species. 60 individuals from six populations were used for chloroplast DNA (cpDNA) sequencing and 100 individuals from five populations were genotyped using 17 nuclear microsatellites. High genetic differentiation among populations was detected, suggesting that pollen or seed dispersal was restricted within populations. Two main genetic clusters were observed in both the cpDNA and microsatellite loci, corresponding to Yunnan China and northern Vietnam. These clusters indicated low levels of gene flow between the regions since their divergence in the late Pleistocene, which was inferred from both Bayesian and coalescent analysis. In addition, the result of a Bayesian skyline plot based on cpDNA portrayed a long history of constant population size followed by a decline in the last 50,000 years of C. multipinnata that was perhaps affected by the Quaternary glaciations, a finding that was also supported by the Garza-Williamson index calculated from the microsatellite data. The genetic consequences produced by climatic oscillations and anthropogenic disturbances are considered key pressures on C. multipinnata. To establish a conservation management plan, each population of C. multipinnata should be recognized as a Management Unit (MU). In situ and ex situ actions, such as controlling overexploitation and creating a germplasm bank with high genetic diversity, should be urgently implemented to preserve this species.
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Project description:Dramatic crustal deformation and river incision in Southwest China induced by the Indo-Asian collision have long been argued to contribute to the complicated landscapes, heterogeneous environment and abundant biodiversity in this region. However, biological impacts in promoting intraspecific phylogeographical subdivision and divergence along the Red River Fault zone (RRF) remain poorly understood. To investigate the possible biological effects of tectonic movements and environment variations within the RRF, the phylogeography of Cycas dolichophylla-an endemic but widely distributed Cycas in Southwest China and North Vietnam along the RRF were carried out based on four chloroplast DNA intergenic spacers (cpDNA), three nuclear DNA sequences (nDNA) and 16 simple sequence repeat variations (SSR). Two different phylogeographical patterns were detected: a Southwest-Northeast break across the RRF disclosed by chlorotypes and a China-Vietnam separation revealed by SSR. A Bayesian skyline plot from cpDNA data demonstrated a historical increasing, but a recent declining, dynamic in population size during the Pleistocene. Consequently, we infer it is the local environmental variation during Cenozoic that contributed to the complex landscape and microclimate mosaics, facilitating speciation and divergence of C. dolichophylla. Subsequently, the Quaternary climatic fluctuations coupled with human activities profoundly influenced the genetic structure and demographic history of this species.
| S-EPMC5024324 | biostudies-literature
Project description:Climate change, species dispersal ability and habitat fragmentation are major factors influencing species distribution and genetic diversity, especially for the range-restricted and threatened taxa. Here, using four sequences of chloroplast DNAs (cpDNAs), three nuclear genes (nDNAs) and 12 nuclear microsatellites (SSRs), we investigated the genetic diversity, genetic structure, divergence time and population dynamics of Cycas segmentifida D. Y. Wang and C. Y. Deng, a threatened cycad species endemic to Southwest China. High levels of genetic diversity and genetic differentiation were revealed in C. segmentifida. Haplotypes of networks showed two evolutionary units in C. segmentifida, with the exception of the nuclear gene GTP network. Meanwhile, the UPGMA tree, structure and PCoA analyses suggested that 14 populations of C. segmentifida were divided into two clades. There was significant effect of isolation by distance (IBD) in this species. However, this species did not display a significant phylogeographic structure. The divergence time estimation suggested that its haplotypes diverged during the Middle Pleistocene. Additionally, the population dynamics inferred from different DNA sequences analyses were discordant. Bottleneck analysis showed that populations of C. segmentifida did not experience any recent bottleneck effect, but rather pointed to a contraction of its effective population size over time. Furthermore, our results suggested that the population BM which held an intact population structure and occupied undisturbed habitat was at the Hardy-Weinberg equilibrium, implying that this population is a free-mating system. These genetic features provide important information for the sustainable management of C. segmentifida.
| S-EPMC5437697 | biostudies-literature
Project description:In this study, we determined the complete chloroplast genome of Cycas szechuanensis (Cycadaceae, Cycas) using the Illumina sequencing data. The genome is 162,083?bp in length, including a pair of inverted repeats (IRs) of 25,003?bp each, which are separated by a large single-copy region (LSC) and a small single-copy region (SSC) with the size of 88,970 and 23,108?bp, respectively. The genome comprises 131 encoded genes in total, including 86 protein-coding genes (82 PCG species), 8 ribosomal RNA genes (4 rRNA species), and 37 transfer RNA genes (30 tRNA species). The overall GC content of the C. szechuanensis chloroplast genome is 39.42%, while the LSC, SSC, and IRs occupy 38.70, 42.03 and 36.52%, respectively. Based on complete chloroplast genome sequences from 13 species, we reconstructed the phylogenetic relationship of the 13 species and found that C. szechuanensis is closely related to C. debaoensis.
| S-EPMC7800925 | biostudies-literature
Project description:Vaccinium duclouxii is an endemic species in China, which is distributed in Sichuan and Yunnan province of China. The chloroplast (cp) genome of V. duclouxii is 168,953?bp in size containing 123 unique genes, including 8 rRNA genes, 38 tRNA genes, and 77 protein-coding genes (PCGs). Phylogenetic analysis exhibited that V. duclouxii and V. macrocarpon were most related to Arbutus unedo.
| S-EPMC7687571 | biostudies-literature
Project description:Primula helodoxa Balf.f. is a species endemic to southeastern China distributed in Tengchong county of Yunnan Province. Here is the first time to report the complete chloroplast genome sequence of P. helodoxa. The complete chloroplast genome was 151,909 bp in length, containing a large single-copy (LSC) region of 83192 bp, a small single-copy (SSC) region of 17,797 bp, and a pair of inverted repeats (IRs) regions of 25,460 bp. There are 137 genes in total, 91 protein-coding genes, eight rRNA genes, and 38 transfer RNA genes. The phylogenetic tree showed relative relationship of P. helodoxa and P. chrysochlora.
| S-EPMC7748870 | biostudies-literature
Project description:Historical geology, climatic oscillations, and seed dispersal capabilities are thought to influence the population dynamics and genetics of plants, especially for distribution-restricted and threatened species. Investigating the genetic resources within and among taxa is a prerequisite for conservation management. The Cycas taiwaniana complex consists of six endangered species that are endemic to South China. In this study, we investigated the relationship between phylogeographic history and the genetic structure of the C. taiwaniana complex. To estimate the phylogeographic history of the complex, we assessed the genetic structure and divergence time, and performed phylogenetic and demographic historical analyses. Two chloroplast DNA intergenic regions (cpDNA), two single-copy nuclear genes (SCNGs), and six microsatellite loci (SSR) were sequenced for 18 populations. The SCNG data indicated a high genetic diversity within populations, a low genetic diversity among populations, and significant genetic differentiation among populations. Significant phylogeographical structure was detected. Structure and phylogenetic analyses both revealed that the 18 populations of the C. taiwaniana complex have two main lineages, which were estimated to diverge in the Middle Pleistocene. We propose that Cycas fairylakea was incorporated into Cycas szechuanensis and that the other populations, which are mainly located on Hainan Island, merged into one lineage. Bayesian skyline plot analyses revealed that the C. taiwaniana complex experienced a recent decline, suggesting that the complex probably experienced a bottleneck event. We infer that the genetic structure of the C. taiwaniana complex has been affected by Pleistocene climate shifts, sea-level oscillations, and human activities. In addition to providing new insights into the evolutionary legacy of the genus, the genetic characterizations will be useful for the conservation of Cycas species.
| S-EPMC6935862 | biostudies-literature
Project description:Cycas ferruginea F. N. Wei (1994) is recorded in the list of wild plant protection in China as a national first-class protected plant. The complete chloroplast genome of C. ferruginea was analyzed for the first time in this article. The genome is 162,045 bp in length, which contains a pair of inverted repeats (IRs) of 25,048 bp each, a large single-copy (LSC) region of 88,827 bp, and a small single-copy (SSC) region of 23,122 bp. The genome comprises a total of 130 encoded genes, including 85 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. The total GC content is 39.44%, and the corresponding values of the LSC, SSC, and IRs are 38.73%, 36.56%, and 42.02%, respectively. The phylogenetic relationships were reconstructed based on the complete chloroplast genome sequences of 16 species. Results showed that C. ferruginea is close to C. debaoensis, C. bifida, and C. szechuanensis.
| S-EPMC9225770 | biostudies-literature
Project description:Zelkova schneideriana Hand.-Mazz. (Ulmaceae) is an endangered species endemic to China. In this study, we reported its complete chloroplast (cp) genome based on Illumina pair-end sequencing. The whole genome was 158,999?bp long, consisting of a pair of inverted repeat (IR) regions of 26,427?bp, a large single copy (LSC) region of 87,397?bp and a small single copy (SSC) region of 18,748?bp. The cp genome contained 133 genes, including 88 protein-coding genes (80 PCG species), 37 tRNA genes (30 tRNA species), and eight rRNA genes (4 rRNA species). The overall G+C content of the whole genome was 35.6%, and the corresponding values of the LSC, SSC, and IR regions were 33.0, 28.3, and 42.4%, respectively. The maximum likelihood phylogenetic analysis of 25 selected chloroplast genomes demonstrated that Z. schneideriana was closely related to Ulmus macrocarpa and Ulmus pumila.
| S-EPMC7800157 | biostudies-literature