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1.
Appl Plant Sci ; 7(11): e11304, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31832286

RESUMO

Premise: We developed single-copy nuclear DNA markers for a perennial herb, Oreocharis auricula (Gesneriaceae), to help infer the evolutionary history of the genus Oreocharis in subtropical China. Methods and Results: We screened 834 putative single-copy nuclear genes from transcriptomes of 11 species of Primulina using the Illumina HiSeq 2000 platform. Based on the screening results, we developed 16 primer sets for accessions of O. auricula representing three wild populations. The number of alleles per locus ranged from three to 34. The levels of expected and observed heterozygosity varied from 0.000 to 0.372 and 0.000 to 0.650, respectively. The markers were successfully cross-amplified in the related species O. magnidens, O. speciosa, O. maximowiczii, and O. henryana. Conclusions: The newly developed markers will facilitate further studies on genetic diversity and phylogeographic structure throughout the distributional range of O. auricula. Additionally, these markers may be useful for other related species in Gesneriaceae.

2.
Mol Phylogenet Evol ; 139: 106567, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31330266

RESUMO

The scaly tree ferns, Cyatheaceae, form a large natural group of ca. 640 species. They comprise an ideal model for studying the biogeography of plants due to their broad distribution across the tropical to south-temperate areas of the world. However, tracing the biogeographic history of this highly diversified group has been hampered by unresolved evolutionary relationships among the major clades. Here, we generated transcriptome sequences of five species in three genera of Cyatheaceae (Alsophila, Gymnosphaera, and Sphaeropteris) and used them to search for single-copy nuclear loci for phylogenetic reconstruction. We identified a total of 818 candidate single-copy loci across multiple Cyatheaceae species. To test their phylogenetic utility, we further obtained sequence data of 12 of these loci for 76 samples representing all 13 known species of scaly tree ferns in China and Vietnam. Phylogenetic analyses based on multispecies coalescent and, alternatively, concatenation models yielded congruent results with high resolution. Additionally, we used the 12 loci to identify genetic signals of hybridization. Overall, our results demonstrated that multiple, single-copy loci are informative and efficient tools for phylogenetic or evolutionary studies of scaly tree ferns.

3.
Mol Phylogenet Evol ; 132: 219-231, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30552965

RESUMO

To consistently and objectively delineate species-level divergence from population subdivision has been a challenge in systematics. This is particularly evident in naturally fragmented and allopatric systems in which small population size often leads to extreme population structuring. Here we evaluated the robustness of the species delimitation methods implemented in BEAST, BPP, and iBPP in the Primulina hochiensis complex comprising four described and one candidate species (five taxa in total) distributed in karst landscapes of southern China. We analyzed levels of molecular and morphological divergence among species using multilocus sequence data (nine chloroplast loci and 10 nuclear loci), and morphological data (16 quantitative and 12 qualitative traits), for 124 individuals from 25 populations of the complex. Independent analyses of cpDNA and nDNA sequence data revealed high levels of genetic differentiation among the five taxa. Both BPP and iBPP delimited five candidate species, which correspond to the five genetic clusters recovered with population structure analysis. In contrast, morphological differences among populations were more limited, so that results from principal component analysis (PCA) recovered only three distinct clusters. We ruled out the possibility of morphologically cryptic species because reciprocally monophyletic groups were not supported among the morphologically un-differentiated taxa. Our results represent a case where extreme population genetic structuring leads to oversplit of species diversity by molecular data using the multispecies coalescent (MSC) methods. The observed congruence across multiple analyses corroborates the recognition of a new species P. lianpingensis and indicates its sister species relationship with P. yingdeensis. This study highlights the dangers of violating model assumption and the importance of incorporating multiple evidence into species delimitation of a particular system.


Assuntos
Magnoliopsida/classificação , Animais , Teorema de Bayes , Núcleo Celular/genética , China , Cloroplastos/genética , DNA Ribossômico/classificação , DNA Ribossômico/genética , Ecossistema , Loci Gênicos , Variação Genética , Magnoliopsida/anatomia & histologia , Filogenia , Análise de Componente Principal
4.
Appl Plant Sci ; 6(6): e01161, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30131903

RESUMO

Premise of the Study: Aconitum reclinatum is the only representative species of Aconitum subg. Lycoctonum in North America, with restricted ranges and endangered populations. Polymorphic microsatellite markers were developed for A. reclinatum for further investigation of genetic diversity and population structure. Methods and Results: Using Illumina HiSeq technology, we sequenced a genomic library for identification of simple sequence repeat markers. A total of 12 polymorphic primer pairs were developed and tested on 66 individuals from four populations in North America. The number of alleles ranged from one to seven per locus with an average of 3.48. Levels of observed and expected heterozygosity varied from 0 to 1.000 and 0 to 0.736, respectively, at population level. Three primer pairs were successfully amplified in three of four closely related species. Conclusions: The microsatellites isolated in this study will be useful in further research on the genetic diversity and conservation genetics of A. reclinatum populations in North America.

5.
Int J Mol Sci ; 19(5)2018 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-29693617

RESUMO

The subfamily Caesalpinioideae of the Fabaceae has long been recognized as non-monophyletic due to its controversial phylogenetic relationships. Cercis chuniana, endemic to China, is a representative species of Cercis L. placed within Caesalpinioideae in the older sense. Here, we report the whole chloroplast (cp) genome of C. chuniana and compare it to six other species from the Caesalpinioideae. Comparative analyses of gene synteny and simple sequence repeats (SSRs), as well as estimation of nucleotide diversity, the relative ratios of synonymous and nonsynonymous substitutions (dn/ds), and Kimura 2-parameter (K2P) interspecific genetic distances, were all conducted. The whole cp genome of C. chuniana was found to be 158,433 bp long with a total of 114 genes, 81 of which code for proteins. Nucleotide substitutions and length variation are present, particularly at the boundaries among large single copy (LSC), inverted repeat (IR) and small single copy (SSC) regions. Nucleotide diversity among all species was estimated to be 0.03, the average dn/ds ratio 0.3177, and the average K2P value 0.0372. Ninety-one SSRs were identified in C. chuniana, with the highest proportion in the LSC region. Ninety-seven species from the old Caesalpinioideae were selected for phylogenetic reconstruction, the analysis of which strongly supports the monophyly of Cercidoideae based on the new classification of the Fabaceae. Our study provides genomic information for further phylogenetic reconstruction and biogeographic inference of Cercis and other legume species.


Assuntos
Fabaceae/genética , Genoma de Cloroplastos , Filogenia , Evolução Molecular , Fabaceae/classificação , Repetições de Microssatélites , Fases de Leitura Aberta , Polimorfismo Genético
6.
Evol Appl ; 10(9): 919-934, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-29151883

RESUMO

Limestone karsts in southern China are characterized by high edaphic and topographic heterogeneity and host high levels of species richness and endemism. However, the evolutionary mechanisms for generating such biodiversity remain poorly understood. Here, we performed species delimitation, population genetic analyses, simulations of gene flow and analyses of floral morphological traits to infer the geographic history of speciation in a species complex of Primulina eburnea from limestone karsts of southern China. Using Bayesian species delimitation, we determined that there are seven distinct species that correspond well to the putative morphological species. Species tree reconstruction, Structure and Neighbor-Net analyses all recovered four lineages in agreement with currently species geographic boundaries. High levels of genetic differentiation were observed both within and among species. Isolation-migration coalescent analysis provides evidence for significant but low gene flow among species. Approximate Bayesian computation (ABC) analysis supports a scenario of historical gene flow rather than recent contemporary gene flow for most species divergences. Finally, we found no evidence of divergent selection contributing to population differentiation of a suite of flower traits. These results support the prevalence of allopatric speciation and highlight the role of geographic isolation in the diversification process. At small geographic scales, limited hybridization occurred in the past between proximate populations but did not eliminate species boundaries. We conclude that limited gene flow might have been the predominant evolutionary force in promoting population differentiation and speciation.

7.
PeerJ ; 5: e4018, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29134154

RESUMO

The herbal medicinal genus Aconitum L., belonging to the Ranunculaceae family, represents the earliest diverging lineage within the eudicots. It currently comprises of two subgenera, A. subgenus Lycoctonum and A. subg. Aconitum. The complete chloroplast (cp) genome sequences were characterized in three species: A. angustius, A. finetianum, and A. sinomontanum in subg. Lycoctonum and compared to other Aconitum species to clarify their phylogenetic relationship and provide molecular information for utilization of Aconitum species particularly in Eastern Asia. The length of the chloroplast genome sequences were 156,109 bp in A. angustius, 155,625 bp in A. finetianum and 157,215 bp in A. sinomontanum, with each species possessing 126 genes with 84 protein coding genes (PCGs). While genomic rearrangements were absent, structural variation was detected in the LSC/IR/SSC boundaries. Five pseudogenes were identified, among which Ψrps19 and Ψycf1 were in the LSC/IR/SSC boundaries, Ψrps16 and ΨinfA in the LSC region, and Ψycf15 in the IRb region. The nucleotide variability (Pi) of Aconitum was estimated to be 0.00549, with comparably higher variations in the LSC and SSC than the IR regions. Eight intergenic regions were revealed to be highly variable and a total of 58-62 simple sequence repeats (SSRs) were detected in all three species. More than 80% of SSRs were present in the LSC region. Altogether, 64.41% and 46.81% of SSRs are mononucleotides in subg. Lycoctonum and subg. Aconitum, respectively, while a higher percentage of di-, tri-, tetra-, and penta- SSRs were present in subg. Aconitum. Most species of subg. Aconitum in Eastern Asia were first used for phylogenetic analyses. The availability of the complete cp genome sequences of these species in subg. Lycoctonum will benefit future phylogenetic analyses and aid in germplasm utilization in Aconitum species.

8.
Mol Ecol ; 26(22): 6414-6429, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28960701

RESUMO

Karst ecosystems in southern China are species-rich and have high levels of endemism, yet little is known regarding the evolutionary processes responsible for the origin and diversification of karst biodiversity. The genus Primulina (Gesneriaceae) comprises ca. 170 species endemic to southern China with high levels of ecological (edaphic) specialization, providing an exceptional model to study the plant diversification in karsts. We used molecular data from nine chloroplast and 11 nuclear regions and macroevolutionary analyses to assess the origin and cause of species diversification due to palaeoenvironmental changes and edaphic specialization in Primulina. We found that speciation was positively associated with changes in past temperatures and East Asian monsoons through the evolutionary history of Primulina. Climatic change around the mid-Miocene triggered an early burst followed by a slowdown of diversification rate towards the present with the climate cooling. We detected different speciation rates among edaphic types, and transitions among soil types were infrequently and did not impact the overall speciation rate. Our findings suggest that both global temperature changes and East Asian monsoons have played crucial roles in floristic diversification within the karst ecosystems in southern China, such that speciation was higher when climate was warmer and wetter. This is the first study to directly demonstrate that past monsoon activity is positively correlated with speciation rate in East Asia. This case study could motivate further investigations to assess the impacts of past environmental changes on the origin and diversification of biodiversity in global karst ecosystems, most of which are under threat.


Assuntos
Biodiversidade , Mudança Climática , Magnoliopsida/classificação , Temperatura Ambiente , Evolução Biológica , Núcleo Celular/genética , China , DNA de Cloroplastos/genética , DNA de Plantas , Ecossistema , Modelos Genéticos , Filogenia , Chuva , Solo
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