scholarly journals Plastomes of eight Ligusticum species: characterization, genome evolution, and phylogenetic relationships

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Ting Ren ◽  
Zi-Xuan Li ◽  
Deng-Feng Xie ◽  
Ling-Jian Gui ◽  
Chang Peng ◽  
...  

Abstract Background The genus Ligusticum consists of approximately 60 species distributed in the Northern Hemisphere. It is one of the most taxonomically difficult taxa within Apiaceae, largely due to the varied morphological characteristics. To investigate the plastome evolution and phylogenetic relationships of Ligusticum, we determined the complete plastome sequences of eight Ligusticum species using a de novo assembly approach. Results Through a comprehensive comparative analysis, we found that the eight plastomes were similar in terms of repeat sequence, SSR, codon usage, and RNA editing site. However, compared with the other seven species, L. delavayi exhibited striking differences in genome size, gene number, IR/SC borders, and sequence identity. Most of the genes remained under the purifying selection, whereas four genes showed relaxed selection, namely ccsA, rpoA, ycf1, and ycf2. Non-monophyly of Ligusticum species was inferred from the plastomes and internal transcribed spacer (ITS) sequences phylogenetic analyses. Conclusion The plastome tree and ITS tree produced incongruent tree topologies, which may be attributed to the hybridization and incomplete lineage sorting. Our study highlighted the advantage of plastome with mass informative sites in resolving phylogenetic relationships. Moreover, combined with the previous studies, we considered that the current taxonomy system of Ligusticum needs to be improved and revised. In summary, our study provides new insights into the plastome evolution, phylogeny, and taxonomy of Ligusticum species.

2017 ◽  
Author(s):  
Meng Wu ◽  
Jamie L. Kostyun ◽  
Matthew W. Hahn ◽  
Leonie Moyle

ABSTRACTPhylogenetic analyses of trait evolution can provide insight into the evolutionary processes that initiate and drive phenotypic diversification. However, recent phylogenomic studies have revealed extensive gene tree-species tree discordance, which can lead to incorrect inferences of trait evolution if only a single species tree is used for analysis. This phenomenon—dubbed “hemiplasy”—is particularly important to consider during analyses of character evolution in rapidly radiating groups, where discordance is widespread. Here we generate whole-transcriptome data for a phylogenetic analysis of 14 species in the plant genus Jaltomata (the sister clade to Solanum), which has experienced rapid, recent trait evolution, including in fruit and nectar color, and flower size and shape. Consistent with other radiations, we find evidence for rampant gene tree discordance due to incomplete lineage sorting (ILS) and several introgression events among the well-supported subclades. Since both ILS and introgression increase the probability of hemiplasy, we perform several analyses that take discordance into account while identifying genes that might contribute to phenotypic evolution. Despite discordance, the history of fruit color evolution in Jaltomata can be inferred with high confidence, and we find evidence of de novo adaptive evolution at individual genes associated with fruit color variation. In contrast, hemiplasy appears to strongly affect inferences about floral character transitions in Jaltomata, and we identify candidate loci that could arise either from multiple lineage-specific substitutions or standing ancestral polymorphisms. Our analysis provides a generalizable example of how to manage discordance when identifying loci associated with trait evolution in a radiating lineage.


Science ◽  
2019 ◽  
Vol 366 (6465) ◽  
pp. 594-599 ◽  
Author(s):  
Nathaniel B. Edelman ◽  
Paul B. Frandsen ◽  
Michael Miyagi ◽  
Bernardo Clavijo ◽  
John Davey ◽  
...  

We used 20 de novo genome assemblies to probe the speciation history and architecture of gene flow in rapidly radiating Heliconius butterflies. Our tests to distinguish incomplete lineage sorting from introgression indicate that gene flow has obscured several ancient phylogenetic relationships in this group over large swathes of the genome. Introgressed loci are underrepresented in low-recombination and gene-rich regions, consistent with the purging of foreign alleles more tightly linked to incompatibility loci. Here, we identify a hitherto unknown inversion that traps a color pattern switch locus. We infer that this inversion was transferred between lineages by introgression and is convergent with a similar rearrangement in another part of the genus. These multiple de novo genome sequences enable improved understanding of the importance of introgression and selective processes in adaptive radiation.


2021 ◽  
Author(s):  
Caitlin Cherryh ◽  
Bui Quang Minh ◽  
Rob Lanfear

AbstractMost phylogenetic analyses assume that the evolutionary history of an alignment (either that of a single locus, or of multiple concatenated loci) can be described by a single bifurcating tree, the so-called the treelikeness assumption. Treelikeness can be violated by biological events such as recombination, introgression, or incomplete lineage sorting, and by systematic errors in phylogenetic analyses. The incorrect assumption of treelikeness may then mislead phylogenetic inferences. To quantify and test for treelikeness in alignments, we develop a test statistic which we call the tree proportion. This statistic quantifies the proportion of the edge weights in a phylogenetic network that are represented in a bifurcating phylogenetic tree of the same alignment. We extend this statistic to a statistical test of treelikeness using a parametric bootstrap. We use extensive simulations to compare tree proportion to a range of related approaches. We show that tree proportion successfully identifies non-treelikeness in a wide range of simulation scenarios, and discuss its strengths and weaknesses compared to other approaches. The power of the tree-proportion test to reject non-treelike alignments can be lower than some other approaches, but these approaches tend to be limited in their scope and/or the ease with which they can be interpreted. Our recommendation is to test treelikeness of sequence alignments with both tree proportion and mosaic methods such as 3Seq. The scripts necessary to replicate this study are available at https://github.com/caitlinch/treelikeness


Phytotaxa ◽  
2021 ◽  
Vol 500 (1) ◽  
pp. 1-10
Author(s):  
MENG-LE XIE ◽  
TIE-ZHENG WEI ◽  
BÁLINT DIMA ◽  
YONG-PING FU ◽  
RUI-QING JI ◽  
...  

This study presents one telamonioid species new to science based on morphological characteristics and molecular phylogenetic analyses. Cortinarius khinganensis was collected from the Greater Khingan Mountains, Northeast China and it is characterized by hygrophanous, vivid brownish red and striate pileus, white universal veil, and subglobose spores. According to phylogenetic analyses results, C. khinganensis belongs to the section Illumini, which is a lineage distantly related from subgenus Telamonia sensu stricto. Detailed descriptions of the new species and the comparisons with morphologically similar species are provided. The phylogenetic relationships within the section Illumini are also discussed.


2020 ◽  
Vol 194 (1) ◽  
pp. 84-99
Author(s):  
Inelia Escobar ◽  
Eduardo Ruiz-Ponce ◽  
Paula J Rudall ◽  
Michael F Fay ◽  
Oscar Toro-Núñez ◽  
...  

Abstract Gilliesieae are a South American tribe of Amaryllidaceae characterized by high floral diversity. Given different taxonomic interpretations and proposals for generic and specific relationships, a representative phylogenetic analysis is required to clarify the systematics of this group. The present study provides a framework for understanding phylogenetic relationships and contributing to the development of an appropriate taxonomic treatment of Gilliesieae. Molecular analyses, based on nuclear (ITS) and plastid DNA sequences (trnL-F and rbcL), resolve with strong support the monophyly of the tribe and the differentiation of two major clades. Clade I comprises the genera Gilliesia, Gethyum and Solaria and Clade II includes Miersia and Speea. These well-supported clades are mostly congruent with vegetative and karyotype characters rather than, e.g., floral symmetry. At the generic level, all molecular analyses reveal the paraphyly of Gilliesia and Miersia. Gethyum was found to be paraphyletic, resulting in the confirmation of Ancrumia as a distinct genus. Several instances of incongruent phylogenetic signals were found among data sets. The calibrated tree suggests a recent diversification of the tribe (Pliocene–Pleistocene), a contemporary process of speciation in which instances of hybridization and incomplete lineage sorting could explain patterns of paraphyly and incongruence of floral morphology.


2020 ◽  
Vol 37 (5) ◽  
pp. 1295-1305 ◽  
Author(s):  
Sean P Mullen ◽  
Nicholas W VanKuren ◽  
Wei Zhang ◽  
Sumitha Nallu ◽  
Evan B Kristiansen ◽  
...  

Abstract Understanding the origin and maintenance of adaptive phenotypic novelty is a central goal of evolutionary biology. However, both hybridization and incomplete lineage sorting can lead to genealogical discordance between the regions of the genome underlying adaptive traits and the remainder of the genome, decoupling inferences about character evolution from population history. Here, to disentangle these effects, we investigated the evolutionary origins and maintenance of Batesian mimicry between North American admiral butterflies (Limenitis arthemis) and their chemically defended model (Battus philenor) using a combination of de novo genome sequencing, whole-genome resequencing, and statistical introgression mapping. Our results suggest that balancing selection, arising from geographic variation in the presence or absence of the unpalatable model, has maintained two deeply divergent color patterning haplotypes that have been repeatedly sieved among distinct mimetic and nonmimetic lineages of Limenitis via introgressive hybridization.


Evolution ◽  
2016 ◽  
Vol 71 (2) ◽  
pp. 475-488 ◽  
Author(s):  
Alana M. Alexander ◽  
Yong-Chao Su ◽  
Carl H. Oliveros ◽  
Karen V. Olson ◽  
Scott L. Travers ◽  
...  

Phytotaxa ◽  
2016 ◽  
Vol 265 (3) ◽  
pp. 225 ◽  
Author(s):  
AUSANA MAPOOK ◽  
KEVIN D. HYDE ◽  
DONG-QIN DAI ◽  
JUNFU LI ◽  
E. B. GARETH JONES ◽  
...  

Muyocopron species are associated with a wide variety of plant substrates worldwide and presently 57 species epithets are listed in Index Fungorum. Species in this genus form distinctive black, dull, rounded regions on the surface of plants and the genus is probably polyphyletic. The present study clarifies the phylogenetic placement of Muyocopron and related species, using fresh tropical collections from northern Thailand. Three Muyocopron species are characterized based on analyses of combined LSU and SSU sequence datasets. Phylogenetic analyses indicate that Muyocopron species form a distinct lineage with the Dyfrolomycetales and Acrospermales lineages. The new order Muyocopronales with three new Muyocopron species is introduced based on its distinct phylogeny and unique morphological characteristics. The taxonomy and phylogenetic relationships of tropical Muyocopron species are reappraised with suggestions for future work.


2021 ◽  
Vol 11 ◽  
Author(s):  
Jinyuan Chen ◽  
Guili Wu ◽  
Nawal Shrestha ◽  
Shuang Wu ◽  
Wei Guo ◽  
...  

Medicago and its relatives, Trigonella and Melilotus comprise the most important forage resources globally. The alfalfa selected from the wild relatives has been cultivated worldwide as the forage queen. In the Flora of China, 15 Medicago, eight Trigonella, and four Melilotus species are recorded, of which six Medicago and two Trigonella species are introduced. Although several studies have been conducted to investigate the phylogenetic relationship within the three genera, many Chinese naturally distributed or endemic species are not included in those studies. Therefore, the taxonomic identity and phylogenetic relationship of these species remains unclear. In this study, we collected samples representing 18 out of 19 Chinese naturally distributed species of these three genera and three introduced Medicago species, and applied an integrative approach by combining evidences from population-based morphological clusters and molecular data to investigate species boundaries. A total of 186 individuals selected from 156 populations and 454 individuals from 124 populations were collected for genetic and morphological analyses, respectively. We sequenced three commonly used DNA barcodes (trnH-psbA, trnK-matK, and ITS) and one nuclear marker (GA3ox1) for phylogenetic analyses. We found that 16 out of 21 species could be well delimited based on phylogenetic analyses and morphological clusters. Two Trigonella species may be merged as one species or treated as two subspecies, and Medicago falcata should be treated as a subspecies of the M. sativa complex. We further found that major incongruences between the chloroplast and nuclear trees mainly occurred among the deep diverging lineages, which may be resulted from hybridization, incomplete lineage sorting and/or sampling errors. Further studies involving a finer sampling of species associated with large scale genomic data should be employed to better understand the species delimitation of these three genera.


ZooKeys ◽  
2019 ◽  
Vol 862 ◽  
pp. 1-22 ◽  
Author(s):  
Tatsuki Koido ◽  
Yukimitsu Imahara ◽  
Hironobu Fukami

The soft coral family Xeniidae, commonly found in tropical and subtropical regions, consists of 20 genera and 162 species. To date, few studies on this family have been conducted in Japan, especially at higher latitudes. Although molecular phylogenetic analyses have recently been used to distinguish soft coral species, it is difficult to identify species and genera in this family due to the limited taxonomic indices and high morphological variation. In this study, we found a large Xeniidae community off the coast of Oshima Island (31°31.35'N, 131°24.27'E) at Miyazaki, Kyushu Island, located in the temperate region of Japan. The species composition and molecular phylogenetic relationships were investigated to uncover the species diversity of Xeniidae in this community. A total of 182 xeniid specimens were collected and identified to the species level, after which the samples were molecularly analyzed using a mitochondrial marker (ND2) and a nuclear marker (ITS) to infer the phylogenetic relationships. A total of 14 xeniid species were identified, including five undescribed species from five genera (Anthelia, Heteroxenia, Sympodium, Xenia, and Yamazatum). Miyazaki was identified as having the highest xeniid species diversity in Japan. The molecular phylogenetic trees inferred from each marker recovered very similar topologies: four genera (Anthelia, Heteroxenia, Sympodium, and Yamazatum) were monophyletic, whereas one (Xenia) was polyphyletic. Thus, except for Xenia, the morphological characteristics used for traditional taxonomy well reflected the phylogeny of the Xeniidae at the genus level. On the other hand, our results show that further taxonomic revisions of Xenia are needed.


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