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25 July 2023, Volume 45 Issue 04
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  • Articles
    Intercontinental comparison of phylogenetic relatedness in introduced plants at the transition from naturalization to invasion: A case study on the floras of South Africa and China
    Hong Qian
    2023, 45(04):  363-368.  doi:10.1016/j.pld.2023.02.003
    Abstract ( 10 )   HTML ( )   PDF (2632KB) ( 5 )   Save
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    Invasive species may pose significant threats to biodiversity and ecosystem structure and functioning. The number of introduced species that have become invasive is substantial and is rapidly increasing. Identifying potentially invasive species and preventing their expansion are of critical importance in invasion ecology. Phylogenetic relatedness between invasive and native species has been used in predicting invasion success. Previous studies on the phylogenetic relatedness of plants at the transition from naturalization to invasion have shown mixed results, which may be because different methods were used in different studies. Here, I use the same method to analyze two comprehensive data sets from South Africa and China, using two phylogenetic metrics reflecting deep and shallow evolutionary histories, to address the question whether the probability of becoming invasive is higher for naturalized species distantly related to the native flora. My study suggests that the probability of becoming invasive is higher for naturalized species closely related to the native flora. The finding of my study is consistent with Darwin's preadaptation hypothesis.
    New patterns of the tree beta diversity and its determinants in the largest savanna and wetland biomes of South America
    Karla J.P. Silva-Souza, Maíra G. Pivato, Vinícius C. Silva, Ricardo F. Haidar, Alexandre F. Souza
    2023, 45(04):  369-384.  doi:10.1016/j.pld.2022.09.006
    Abstract ( 11 )   HTML ( )   PDF (16022KB) ( 3 )   Save
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    Clear and data-driven bioregionalizations can provide a framework to test hypotheses and base biodiversity conservation. Here we used occurrence and abundance data in combination with objective analytical methods to propose two bioregionalization schemes for tree species of the Cerrado and the Pantanal in South America. We also evaluated the contribution of three sets of determinants of the occurrence- and abundance-based subregions. We compiled data on tree species composition from 894 local assemblages based on species occurrences, and from 658 local assemblages based on species abundances. We used an unconstrained community-level modelling approach and clustering techniques to identify and map tree subregions for the occurrence and the abundance data sets, separately. Hierarchical clustering analyses were conducted to investigate floristic affinities between the subregions and to map broader floristic regions. We used multinomial logistic regression models, deviance partitioning, and rank-sum tests to assess the main subregion correlates. We identified 18 occurrence- and four abundance-based subregions in the Cerrado-Pantanal. The hierarchical classifications grouped the occurrence-based subregions into nine floristic zones and abundance-based subregions into two broad floristic zones. Variation in subregions were explained mainly by environmental factors and spatial structure in both occurrence and abundance data sets. The occurrence- and abundance-based subregions are complementary approaches to disentangle macroecological patterns and to plan conservation efforts in the Cerrado and the Pantanal. Our findings based on occurrence data revealed more complex and interdigitated boundaries between subregions of tree species than previously reported. The environment, historical stability, and human effects act in a synergetic way on the distribution of the subregions. Finally, the relevance of contemporary environmental factors to the subregion patterns we found alert us to the profound impact global warming may have on the spatial organization of the Cerrado-Pantanal tree flora.
    Functional diversity in an Andean subpáramo affected by wildfire in Colombia
    Korina Ocampo-Zuleta, Ángela Parrado-Rosselli
    2023, 45(04):  385-396.  doi:10.1016/j.pld.2022.11.007
    Abstract ( 7 )   HTML ( )   PDF (4442KB) ( 1 )   Save
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    Recently, the Andean subpáramo in Colombia has experienced severe wildfires, but little is known about the functional composition of recovering or not after a wildfire. Therefore, we examined the functional community composition subpáramo affected by fire in 2016. We documented how functional traits changed 31 months after the disturbance and compared them with an unburned site. We sampled from one to two years after the fire every four months, then registered all recruits in 16 5×5m plots. New individuals were classified into strategy functional groups based on the traits of persistence and dispersal. The first group was stem type and regeneration mechanism (seedling and resprout), and the second was fruit type and dispersal mode. We investigated the degree to which functional diversity changes plant communities over time (woody and non-woody), and we compared it with an unburned site. The most relevant results showed that resprouts and seed regenerated increased post-fire time and significant differences between sampling periods. The anemochory is the most relevant dispersal mode that indicates the community capacity to colonize the new gaps opened by the fire rapidly. We discuss how wildfire appears to be a triggering factor for persistence and dispersal strategy groups in subpáramo burned given their characteristics of tolerance to stress. For this reason, a greater functional divergence between the ecosystems studied post-fire recovery has been related to higher levels of biodiversity at the landscape scale due to the high degree of endemism and significant differences in species composition between páramos.
    Molecular phylogeny and inflorescence evolution of Prunus (Rosaceae) based on RAD-seq and genome skimming analyses
    Na Su, Richard G.J. Hodel, Xi Wang, Jun-Ru Wang, Si-Yu Xie, Chao-Xia Gui, Ling Zhang, Zhao-Yang Chang, Liang Zhao, Daniel Potter, Jun Wen
    2023, 45(04):  397-408.  doi:10.1016/j.pld.2023.03.013
    Abstract ( 15 )   HTML ( )   PDF (8751KB) ( 22 )   Save
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    Prunus is an economically important genus widely distributed in the temperate Northern Hemisphere. Previous studies on the genus using a variety of loci yielded conflicting phylogenetic hypotheses. Here, we generated nuclear reduced representation sequencing data and plastid genomes for 36 Prunus individuals and two outgroups. Both nuclear and plastome data recovered a well-resolved phylogeny. The species were divided into three main clades corresponding to their inflorescence types, - the racemose group, the solitary-flower group and the corymbose group - with the latter two sister to one another. Prunus was inferred to have diversified initially in the Late Cretaceous around 67.32 million years ago. The diversification of the three major clades began between the Paleocene and Miocene, suggesting that paleoclimatic events were an important driving force for Prunus diversification. Ancestral state reconstructions revealed that the most recent common ancestor of Prunus had racemose inflorescences, and the solitary-flower and corymb inflorescence types were derived by reduction of flower number and suppression of the rachis, respectively. We also tested the hybrid origin hypothesis of the racemose group proposed in previous studies. Prunus has undergone extensive hybridization events, although it is difficult to identify conclusively specific instances of hybridization when using SNP data, especially deep in the phylogeny. Our study provides well-resolved nuclear and plastid phylogenies of Prunus, reveals substantial cytonuclear discord at shallow scales, and sheds new light on inflorescence evolution in this economically important lineage.
    Phylogeny of Trigonotis in China—with a special reference to its nutlet morphology and plastid genome
    Xue-Min Xu, Dan-Hui Liu, Shi-Xin Zhu, Zhen-Long Wang, Zhen Wei, Quan-Ru Liu
    2023, 45(04):  409-421.  doi:10.1016/j.pld.2023.03.004
    Abstract ( 12 )   HTML ( )   PDF (20880KB) ( 6 )   Save
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    The genus Trigonotis comprises nearly 60 species mainly distributed in East and Southeast Asia. China has the largest number of Trigonotis species in the world, with a total of 44 species, of which 38 are endemic. Nutlet morphology is useful for the taxonomic delimitation of Trigonotis. However, there are still controversial circumscriptions of nutlet shape in some species. In previous studies, interspecies phylogenetic relationships were inferred using few DNA markers and very few taxa, which possibly led to erroneous or incomplete conclusions. In this study, the nutlet morphology of 39 Trigonotis taxa and the characteristics of 34 complete chloroplast genomes (29 taxa) were investigated and analyzed. Then, the phylogenetic relationships were discussed within this genus based on complete chloroplast genomes. To the best of our knowledge, this study is the first comprehensive analysis of nutlet morphology and complete chloroplast genome of Trigonotis. Based on nutlet morphology, Trigonotis can be divided into two groups: Group 1, hemispherical or oblique tetrahedron with carpopodiums, and Group 2, inverted tetrahedron without carpopodiums. The chloroplast genome of Trigonotis exhibited a typical quadripartite structure, including 84–86 protein-coding, 37 transfer RNA, and 8 ribosomal RNA genes, with a total length of 147,247–148,986 bp. Genes in the junctions were well conserved in Trigonotis, similar to those in other Boraginaceae s.str. species. Furthermore, Trigonotis chloroplast genomes showed relatively high diversity, with more conserved genic regions than intergenic regions; in addition, we detected 14 hot spots (Pi > 0.005) in non-coding regions. Phylogenetic analyses based on chloroplast genome data identified highly resolved relationships between Trigonotis species. Specifically, Trigonotis was divided into two clades with strong support: one clade included species with hemispherical or oblique tetrahedron nutlets with carpopodiums and bracts, whereas the other clade included species with inverted tetrahedron nutlets without carpopodiums or bracts. Our results may inform future taxonomic, phylogenetic, and evolutionary studies on Boraginaceae.
    Forest characteristics, population structure and growth trends of threatened relict Pseudotsuga forrestii in China
    Cindy Q. Tang, Shi-Qian Yao, Peng-Bin Han, Jian-Ran Wen, Shuaifeng Li, Ming-Chun Peng, Chong-Yun Wang, Tetsuya Matsui, Yong-Ping Li, Shan Lu, Yuan He
    2023, 45(04):  422-433.  doi:10.1016/j.pld.2022.10.005
    Abstract ( 10 )   HTML ( )   PDF (8499KB) ( 4 )   Save
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    Pseudotsuga forrestii is a relict evergreen coniferous tree species in Pinaceae endemic to China. P. forrestii tree numbers have greatly decreased due to deforestation, over-utilization and habitat degradation. Here we clarify P. forrestii community types, structure, species diversity, seedling recruitments and growth trends. We identified four P. forrestii community types: (1) Pseudotsuga forrestii - Quercus guyavifolia - Acer davidii evergreen coniferous and broad-leaved mixed forest; (2) Pseudotsuga forrestii - Pinus yunnanensis - Quercus guyavifolia evergreen coniferous and broad-leaved mixed forest; (3) Pseudotsuga forrestii evergreen coniferous forest; (4) Pseudotsuga forrestii - Abies georgei var. smithii evergreen coniferous forest. P. forrestii forests are characterized by both warm temperate and temperate affinities. Simpson diversity, Pielou evenness, Shannon–Wiener diversity indices ranged from 0.75 to 0.76, 0.74–0.81, and 1.62–1.93, respectively, with no significant differences among the four forest types. The forest stratification was multilayered. The canopy layer was generally 10–25 m tall, with the emergent layer reached 25–42 m. DBH and age structures of P. forrestii showed multimodal distributions. Its maximum age P. forrestii was 570 years with a DBH of 143 cm. The growth of annual ring width of P. forrestii was slow, and generally decreased with age, whereas the basal area at the breast height increased with age. Established seedlings/saplings were mainly found in unstable micro-habitats. Regeneration of P. forrestii depends on moderate natural disturbances. Finally, we provide recommendations for P. forrestii conservation.
    Late Oligocene fossil acorns and nuts of Quercus section Cyclobalanopsis from the Nanning Basin, Guangxi, South China
    Xiao-Yan Liu, Han-Zhang Song, Xin-Kai Wu, Jia-Rong Hu, Wei-Ye Huang, Cheng Quan, Jian-Hua Jin
    2023, 45(04):  434-445.  doi:10.1016/j.pld.2022.08.002
    Abstract ( 11 )   HTML ( )   PDF (24647KB) ( 2 )   Save
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    Quercus is the largest genus within the Fagaceae and has a rich fossil record. Most of the fossil material is attributed to the subgenus Quercus based on leaves, pollen or rarely acorns and nuts. Fossil records of Q. section Cyclobalanopsis characterized by ring-cupped acorns are relatively few and especially those described based on nuts are scant. In this study, we described four new species of Quercus section Cyclobalanopsis based on mummified acorns and nuts: Q. paleodisciformis X.Y. Liu et J.H. Jin sp. nov., Q. paleohui X.Y. Liu et J.H. Jin sp. nov., Q. nanningensis X.Y. Liu et J.H. Jin sp. nov. and Q. yongningensis X.Y. Liu et J.H. Jin sp. nov. These species closely resemble the extant species Q. disciformis, Q. hui, Q. kerrii, and Q. dinghuensis. The occurrence of Q. section Cyclobalanopsis in the Oligocene stratum of Guangxi, South China, suggests that the section has diversified within its extant distribution center since the Oligocene. By combining records from other areas, we propose that the section first appeared in the middle Eocene of East Asia (Sino-Japan), has diversified in situ with a few elements scattering into West Asia and southern Europe since the Oligocene and Pliocene, respectively, and finally became restricted in East Asia since the Pleistocene. This indicates that the section originated and diversified in East Asia, before spreading into West Asia no later than the Oligocene and into southern Europe by the Pliocene. Subsequently it disappeared from South Europe and West Asia due to the appearance of the (summer dry) Mediterranean climate and widespread cooling during the Pleistocene.
    Does pollinator dependence decrease along elevational gradients?
    Yue-Wen Xu, Lu Sun, Rong Ma, Yong-Qian Gao, Hang Sun, Bo Song
    2023, 45(04):  446-455.  doi:10.1016/j.pld.2023.03.006
    Abstract ( 13 )   HTML ( )   PDF (3232KB) ( 5 )   Save
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    Plants have long been thought to be less dependent on pollinators for seed production at higher elevations due to adverse pollination environments. However, recent research has yet to consistently support the generality of this expectation. In this study, we asked whether pollinator dependence decreases along an elevational gradient and how it varies with various reproductive traits. To answer these questions, we quantified pollinator–plant associations and various reproductive traits for 112 flowering plants spanning a large elevational gradient (990–4260 m a.s.l.) in the Qinghai-Tibet Plateau. We found that flowering plants in the Qinghai-Tibet Plateau region are highly dependent on pollinators for seed production (76.2% of seed production was contributed by animal pollinators and 44.6% of plants would produce no seed without pollinator visitation). Contrary to our expectation, there was no significant elevational gradient in pollinator dependence index. Although the pollinator dependence index was not significantly correlated with pollen limitation, flower size, floral longevity, or reward type, it was correlated with compatibility status and flowering time. These findings indicate that pollinator dependence does not decrease along an elevational gradient in the Qinghai-Tibet Plateau. Our study also highlights the severe vulnerability of flowering plant seed production to pollinator declines under global change in the Qinghai-Tibet Plateau region, particularly for early-flowering or self-incompatible plants growing at higher elevations (e.g., subnival belt).
    Pre- and post-pollination barriers between two exotic and five native Sagittaria species: Implications for species conservation
    Ting-Ting Zou, Sen-Tao Lyu, Qi-Lin Jiang, Shu-He Shang, Xiao-Fan Wang
    2023, 45(04):  456-468.  doi:10.1016/j.pld.2022.10.001
    Abstract ( 8 )   HTML ( )   PDF (3902KB) ( 1 )   Save
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    Anthropogenic introduction of species has resulted in a breakdown of geographical barriers and hybridization in previously allopatric species. Thus, examining hybridization proneness of exotic species contributes to revealing its potential threat. Moreover, reproductive barriers may be strengthened or weakened due to long-term geographical isolation for these newly sympatric species. However, few studies have evaluated multiple barriers between alien and native species. In this study, we quantified the importance of four pre-pollination barriers (phenological, floral traits, pollen production, and floral constancy) and four post-pollination barriers (pollen-pistil incompatibility, seed set, seed viability, and seedling survival) between two introduced and five native Sagittaria species. Results showed that introduced S. platyphylla was cross-compatible with two native species, whereas introduced S. montevidensis was incapable of hybridizing with any native species. Different barriers were asymmetric within species pairs and multiple barriers acted in concert to maintain species boundaries. Post-pollination barriers contributed more to total reproductive isolation in native species, whereas pre-pollination barriers played a stronger role in total reproductive isolation for two introduced species. Seed set was the only barrier that was positively correlated with genetic distance. Our results provide a perspective to better understand reproductive barriers for secondary contact species. We highlight the importance of monitoring hybridization events before human introduction and the possible conservation strategies to remove invasive species with hybridization proneness.
    The molecular mechanism of WRINKLED1 transcription factor regulating oil accumulation in developing seeds of castor bean
    Qing Tan, Bing Han, Mohammad Enamul Haque, Ye-Lan Li, Yue Wang, Di Wu, Shi-Bo Wu, Ai-Zhong Liu
    2023, 45(04):  469-478.  doi:10.1016/j.pld.2022.09.003
    Abstract ( 7 )   HTML ( )   PDF (8011KB) ( 2 )   Save
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    The transcription factor WRINKLED1 (WRI1), a member of AP2 gene family that contain typical AP2 domains, has been considered as a master regulator regulating oil biosynthesis in oilseeds. However, the regulatory mechanism of RcWRI1 in regulating oil accumulation during seed development has not been clearly addressed. Castor bean (Ricinus communis) is one of the most important non-edible oil crops and its seed oils are rich in hydroxy fatty acids, widely applied in industry. In this study, based on castor bean reference genome, three RcWRIs genes (RcWRI1, RcWRI2 and RcWRI3) were identified and the expressed association of RcWRI1 with oil accumulation were determined. Heterologous transformation of RcWRI1 significantly increased oil content in tobacco leaf, confirming that RcWRI1 activate lipid biosynthesis pathway. Using DNA Affinity Purification sequencing (DAP-seq) technology, we confirmed RcWRI1 binding with Transcription Start Site of genes and identified 7961 WRI1-binding candidate genes. Functionally, these identified genes were mainly involved in diverse metabolism pathways (including lipid biosynthesis). Three cis-elements AW-box ([CnTnG](n)7[CG]) and AW-boxes like ([GnAnC](n)6[GC]/[GnAnC](n)7[G]) bound with RcWRI1 were identified. Co-expression network analysis of RcWRI1 further found that RcWRI1 might be widely involved in biosynthesis of storage materials during seed development. In particular, yeast one hybrid experiments found that both AP2 domains within RcWRI1 were required in binding targeted genes. These results not only provide new evidence to understand the regulatory mechanism of RcWRI1 in regulation of oil accumulation during castor bean seed development, but also give candidate gene resource for subsequent genetic improvement toward increasing oil content in oilseed crops.
    Short communication
    Endemic medicinal plant distribution correlated with stable climate, precipitation, and cultural diversity
    Gang Feng, Ying-Jie Xiong, Hua-Yu Wei, Yao Li, Ling-Feng Mao
    2023, 45(04):  479-484.  doi:10.1016/j.pld.2022.09.007
    Abstract ( 8 )   HTML ( )   PDF (3512KB) ( 1 )   Save
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    Medicinal plants provide crucial ecosystem services, especially in developing countries such as China, which harbors diverse endemic medicinal plant species with substantial cultural and economic value. Accordingly, understanding the patterns and drivers of medicinal plant distribution is critical. However, few studies have investigated the patterns and drivers of endemic medicinal plants distribution in China. Here, we linked endemic medicinal plants distribution with possible explanatory variables, i.e., paleoclimate change, contemporary climate, altitudinal range and ethnic minority human population size at the prefecture city level in China. Our results show that endemic medicinal plants are concentrated in southern China, especially in southwestern China. Notably, both endemic medicinal plant species richness and the ratio of endemic medicinal plant species richness are negatively associated with glacial-interglacial anomaly in temperature, and positively associated with contemporary precipitation and altitudinal range. In addition, we found that endemic medicinal plant species richness is positively associated with ethnic minority population sizes as well as its ratio to the overall population size. These findings suggest that the distribution of endemic medicinal plants is determined by multiple drivers. Furthermore, our findings stress that dramatic future climate changes and massive anthropogenic activities in southern China pose great challenges to the conservation of China's endemic medicinal plants.
    Mitochondrial RNA editing sites affect the phylogenetic reconstruction of gymnosperms
    Shan-Shan Dong, Xu-Ping Zhou, Tao Peng, Yang Liu
    2023, 45(04):  485-489.  doi:10.1016/j.pld.2023.02.004
    Abstract ( 11 )   HTML ( )   PDF (3571KB) ( 10 )   Save
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