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The identification and understanding of cryptic intraspecific evolutionary units (lineages) are crucial for planning effective conservation strategies aimed at preserving genetic diversity in endangered species. However, the factors driving the evolution and maintenance of these intraspecific lineages in most endangered species remain poorly understood. In this study, we conducted resequencing of 77 individuals from 22 natural populations of Davidia involucrata, a “living fossil” dove tree endemic to central and southwest China. Our analysis revealed the presence of three distinct local lineages within this endangered species, which emerged approximately 3.09 and 0.32 million years ago. These divergence events align well with the geographic and climatic oscillations that occurred across the distributional range. Additionally, we observed frequent hybridization events between the three lineages, resulting in the formation of hybrid populations in their adjacent as well as disjunct regions. These hybridizations likely arose from climate-driven population expansion and/or long-distance gene flow. Furthermore, we identified numerous environment-correlated gene variants across the total and many other genes that exhibited signals of positive evolution during the maintenance of two major local lineages. Our findings shed light on the highly dynamic evolution underlying the remarkably similar phenotype of this endangered species. Importantly, these results not only provide guidance for the development of conservation plans but also enhance our understanding of evolutionary past for this and other endangered species with similar histories.

The phylogenetic position of the monotypic woody Parapteropyrum (Polygonaceae) remains controversial. Parapteropyrum has been thought to be closely related to the woody genera of the tribe Atraphaxideae, although some evidence indicates that it nests within the herbal buckwheat genus Fagopyrum of tribe Polygoneae. In this study, we used plastome data to determine the phylogenetic position of Parapteropyrum (Fagopyrum) tibeticum. Different reference species were used to assemble plastomes of three species currently placed in the tribe Ataphaxideae: Parapteropyrum (Fagopyrum) tibeticum, Atraphaxis bracteata and Calligonum ebinuricum. Once assembled, plastomes were characterized and compared to plastomes of 12 species across the family Polygonaceae. Phylogenetic analyses of Polygonaceae were performed using whole plastome, all plastome genes, and single-copy genes. Plastomes assembled using different reference plastomes did not differ; however, annotations showed small variation. Plastomes of Parapteropyrum (Fagopyrum) tibeticum, A. bracteata and C. ebinuricum have the typical quadripartite structure with lengths between 159,265 bp and 164,270 bp, and a total number of plastome genes of about 130. Plastome microsatellites (SSR) ranged in number from 48 to 77. Maximum Likelihood and Bayesian analyses of three plastome data sets consistently nested Parapteropyrum within the genus Fagopyrum. Furthermore, our analyses indicated that sampled woody genera of the family Polygonaceae are polyphyletic. Our study provides strong evidence that the woody Parapteropyrum tibeticum, which is distantly related to woody genera sampled here, should be taxonomically placed under Fagopyrum as Fagopyrum tibeticum.

Toona sinensis is an economic and medicinal plant endemic in China. In this study, the complete chloroplast genome of T. sinensis was assembled using the second-generation high-throughput sequencing data. The genome consists of 138 genes in total, including 89 protein-coding genes, 7 ribosomal RNA genes, 40 transfer RNA genes and 2 pseudogenes. Phylogenetic analysis indicated that T. sinensis has a close relationship with the Toona ciliata with strong support. The chloroplast genome presented here provides a valuable resource to conserve this valuable species.

Nannoglottis ravida is an extremely endangered species in the Qinghai-Tibet Plateau. Based on the second-generation high-throughput genome sequencing, we assembled the plastome of this species. The length of the total plastome is 152,324 bp with a typical quadripartite structure including a large single-copy region of 83,708 bp, a small single-copy region of 29,882 bp and two reverse repeat regions of 19,367 bp respectively. A total of 131 genes were annotated including 85 protein-coding genes (PCG), 36 tRNA genes, 8 rRNA genes and 2 pseudogenes. The constructed phylogenetic tree with other species of two tribes Senecioneae and Astereae based on plastomes suggests that N. ravida has a close relationship with the Astereae, but diverged early from this tribe.

Torreya parvifolia (Torreya, Taxaceae) is endemic in Sichuan, China. It consisted of an extremely small population with less than 100 wild individuals. In this study, the complete chloroplast genome of T. parvifolia was assembled using the Illumina data. The complete chloroplast genome of T. parvifolia is 137,106 bp in length. The genome consists of 119 genes in total, including 82 protein-coding genes (PCGs), 4 ribosomal RNA (rRNA) genes, and 33 transfer RNA (tRNA) genes. Phylogenetic analysis indicated that T. parvifolia was closely related to T. fargesii, T. nucifera, and T. fargesii var. yunnanensis with strong support.

Antiaris toxicaria (Antiaris, Moraceae) is a medicinal and extremely toxic species. To facilitate species identification and provide genetic information, we determined the complete chloroplast genome of A. toxicaria using the Illumina platform. The genome was 161,412 bp in length, comprising a large single-copy region (LSC) of 89,883 bp, a small single-copy region (SSC) of 20,375 bp, and a pair of inverted repeats (IRs) of 25,577 bp each. The genome contained 130 encoded genes in total, including 85 protein-coding genes, 8 ribosomal RNA genes, and 37 transfer RNA genes. The overall GC content of the A. toxicaria chloroplast genome is 35.87%. The phylogenetic analysis revealed A. toxicaria was closely related to the genus Ficus within the family Moraceae.

Pterospermum kingtungense (Pterospermum, Sterculiaceae) is a Critically Endangered species. In this study, we reported a complete chloroplast genome of P. kingtungense based on high-throughput sequencing data. The size of chloroplast genome was 162,929 bp, including a large single-copy region (LSC: 91,535 bp) and a small single-copy region (SSC: 20,464 bp), separated by a pair of inverted repeats (IRa and IRb: 25,465 bp). The genome encoded 126 genes in total, including 81 protein-coding genes, 8 ribosomal RNA genes, and 37 transfer RNA genes. The overall GC content of the P. kingtungense chloroplast genome is 36.39%. The phylogenetic tree showed P. kingtungense clustered together with the family Sterculiaceae.

Pollination is an important part of fertilization and reproduction in seed plants. Pollen movement largely restricts gene flow among individual plants and the manner of reproduction in a population, thereby affecting the genetic traits and fitness of plant offspring. For insect-pollinator-based plants, the flower-visiting characteristics, frequency and timing of the pollinating insects have decisive effects on the successful pollination of plants, whereas the colour and morphology of various floral components are important factors affecting the pollinating insects. Based on the pollination biology of plants, we studied the pollination mechanisms and links of Urophysa rochkii to understand its endangered status. Using U. rochkii at the full flowering period for the study, and using methods to observe, record, and perform experimental analysis, we recorded the species, frequency and flower-visiting time of these insects every 15 min and observed the effects of weather and temperature on the insects. Additionally, we captured the flower-visiting insects, brought them to the laboratory, and took photographs under a dissecting electron microscope for observation and identification. U. rochkii plants were grouped under different treatments that included removal of sepals, stamens and or pistils, while untreated plants were included as control group. In summary, the effects of floral components on the pollination process were examined. The experimental results showed that the effective pollinator of U. rochkii was Apis cerana Fabricius, and that sky-blue sepal was the most important factor affecting the flower-visiting frequency of the pollinators. [ABSTRACT FROM AUTHOR]