scholarly journals Comparative Analysis of Chloroplast Genomes of Seven Chaetoceros Species Revealed Variation Hotspots and Speciation Time

2021 ◽  
Vol 12 ◽  
Author(s):  
Qing Xu ◽  
Zongmei Cui ◽  
Nansheng Chen
Keyword(s):  
Divergence Time ◽  
Evolutionary Relationship ◽  
Gc Content ◽  
Time Estimation ◽  
Divergence Time Estimation ◽  
Chloroplast Genomes ◽  
Diatom Genus ◽  
The Common ◽  
Genome Arrangement ◽  
Global Carbon

Chaetoceros is a species-rich diatom genus with broad distribution and plays an important role in global carbon cycle and aquatic ecosystems. However, genomic information of Chaetoceros species is limited, hindering advanced researches on Chaetoceros biodiversity and their differential impact on ecology. In this study, we constructed full-length chloroplast genomes (cpDNAs) for seven Chaetoceros species, including C. costatus, C. curvisetus, C. laevisporus, C. muelleri, C. pseudo-curvisetus, C. socialis, and C. tenuissimus. All of these cpDNAs displayed a typical quadripartite structure with conserved genome arrangement and specific divergence. The sizes of these cpDNAs were similar, ranging from 116,421 to 119,034 bp in size, and these cpDNAs also displayed similar GC content, ranging from 30.26 to 32.10%. Despite extensive synteny conservation, discrete regions showed high variations. Divergence time estimation revealed that the common ancestor of Chaetoceros species, which formed a monophyletic clade at approximately 58 million years ago (Mya), split from Acanthoceras zachariasii at about 70 Mya. The availability of cpDNAs of multiple Chaetoceros species provided valuable reference sequences for studying evolutionary relationship among Chaetoceros species, as well as between Chaetoceros species and other diatom species.

scholarly journals Chloroplast phylogenomics in Camelina (Brassicaceae) reveals multiple origins of polyploid species and the maternal lineage of C. sativa

2022 ◽  
Vol 9 ◽  
Author(s):  
Jordan R Brock ◽  
Terezie Mandáková ◽  
Michael McKain ◽  
Martin A Lysak ◽  
Kenneth M Olsen
Keyword(s):  
Phylogenetic Analyses ◽  
Divergence Time ◽  
Diploid Species ◽  
Time Estimation ◽  
Polyploid Species ◽  
Chromosome Counts ◽  
Diploid Parent ◽  
Divergence Time Estimation ◽  
Multiple Origins ◽  
Chloroplast Genomes

Abstract The genus Camelina (Brassicaceae) comprises 7–8 diploid, tetraploid, and hexaploid species. Of particular agricultural interest is the biofuel crop, C. sativa (gold-of-pleasure or false flax), an allohexaploid domesticated from the widespread weed, C. microcarpa. Recent cytogenetics and genomics work has uncovered the identity of the parental diploid species involved in ancient polyploidization events in Camelina. However, little is known about the maternal subgenome ancestry of contemporary polyploid species. To determine the diploid maternal contributors of polyploid Camelina lineages, we sequenced and assembled 84 Camelina chloroplast genomes for phylogenetic analysis. Divergence time estimation was used to infer the timing of polyploidization events. Chromosome counts were also determined for 82 individuals to assess ploidy and cytotypic variation. Chloroplast genomes showed minimal divergence across the genus, with no observed gene-loss or structural variation. Phylogenetic analyses revealed C. hispida as a maternal diploid parent to the allotetraploid Camelina rumelica, and C. neglecta as the closest extant diploid contributor to the allohexaploids C. microcarpa and C. sativa. The tetraploid C. rumelica appears to have evolved through multiple independent hybridization events. Divergence times for polyploid lineages closely related to C. sativa were all inferred to be very recent, at only ~65 thousand years ago. Chromosome counts confirm that there are two distinct cytotypes within C. microcarpa (2n = 38 and 2n = 40). Based on these findings and other recent research, we propose a model of Camelina subgenome relationships representing our current understanding of the hybridization and polyploidization history of this recently-diverged genus.

scholarly journals Out of the Qinghai-Tibetan Plateau (QTP) and rapid radiation across Eurasia for Allium section Daghestanica (Amaryllidaceae)

AoB Plants ◽  
2021 ◽  
Author(s):  
Min-Jie Li ◽  
Huan-Xi Yu ◽  
Xian-Lin Guo ◽  
Xing-Jin He
Keyword(s):  
Evolutionary History ◽  
Divergence Time ◽  
Time Estimation ◽  
Adjacent Region ◽  
Rapid Radiation ◽  
Divergence Time Estimation ◽  
Species Diversification ◽  
The Third ◽  
Evolutionary Line ◽  
History Of

Abstract The disjunctive distribution (Europe-Caucasus-Asia) and species diversification across Eurasia for the genus Allium sect. Daghestanica has fascinating attractions for researchers aiming to understanding the development and history of the modern Eurasia flora. However, no any studies have been carried out to address the evolutionary history of this section. Based on the nrITS and cpDNA fragments (trnL-trnF and rpl32-trnL), the evolutionary history of the third evolutionary line (EL3) of the genus Allium was reconstructed and we further elucidate the evolutionary line of sect. Daghestanica under this background. Our molecular phylogeny recovered two highly supported clades in sect. Daghestanica: the Clade I includes Caucasian-European species and Asian A. maowenense, A. xinlongense and A. carolinianum collected in Qinghai; the Clade II comprises Asian yellowish tepal species, A. chrysanthum, A. chrysocephalum, A. herderianum, A. rude and A. xichuanense. The divergence time estimation and biogeography inference indicated that Asian ancestor located in the QTP and the adjacent region could have migrated to Caucasus and Europe distributions around the Late Miocene and resulted in further divergence and speciation; Asian ancestor underwent the rapid radiation in the QTP and the adjacent region most likely due to the heterogeneous ecology of the QTP resulted from the orogeneses around 4–3 Mya. Our study provides a picture to understand the origin and species diversification across Eurasia for sect. Daghestanica.

Taxonomy, phylogeny, and divergence time estimation for Apiosphaeria guaranitica, a Neotropical parasite on bignoniaceous hosts

Mycologia ◽  
2018 ◽  
Vol 110 (3) ◽  
pp. 526-545 ◽  
Author(s):  
Debora Cervieri Guterres ◽  
Samuel Galvão-Elias ◽  
Bruno Cézar Pereira de Souza ◽  
Danilo Batista Pinho ◽  
Maria do Desterro Mendes dos Santos ◽  
...  
Keyword(s):  
Divergence Time ◽  
Time Estimation ◽  
Divergence Time Estimation

scholarly journals Correction: Large-scale molecular phylogeny, morphology, divergence-time estimation, and the fossil record of advanced caenophidian snakes (Squamata: Serpentes)

PLoS ONE ◽  
2019 ◽  
Vol 14 (5) ◽  
pp. e0217959 ◽  
Author(s):  
Hussam Zaher ◽  
Robert W. Murphy ◽  
Juan Camilo Arredondo ◽  
Roberta Graboski ◽  
Paulo Roberto Machado-Filho ◽  
...  
Keyword(s):  
Molecular Phylogeny ◽  
Fossil Record ◽  
Large Scale ◽  
Divergence Time ◽  
Time Estimation ◽  
Divergence Time Estimation

scholarly journals Uncertainty in divergence time estimation

2020 ◽  
Author(s):  
Tom Carruthers ◽  
Robert W Scotland
Keyword(s):  
Fossil Record ◽  
Academic Research ◽  
Divergence Time ◽  
Time Estimation ◽  
Divergence Time Estimation ◽  
Diversification Rates ◽  
Divergence Time Estimates ◽  
Use Of Time ◽  
Time Estimates ◽  
Highly Sensitive

Abstract Understanding and representing uncertainty is crucial in academic research, because it enables studies to build on the conclusions of previous studies, leading to robust advances in a particular field. Here, we evaluate the nature of uncertainty and the manner by which it is represented in divergence time estimation, a field that is fundamental to many aspects of macroevolutionary research, and where there is evidence that uncertainty has been seriously underestimated. We address this issue in the context of methods used in divergence time estimation, and with respect to the manner by which time-calibrated phylogenies are interpreted. With respect to methods, we discuss how the assumptions underlying different methods may not adequately reflect uncertainty about molecular evolution, the fossil record, or diversification rates. Therefore, divergence time estimates may not adequately reflect uncertainty, and may be directly contradicted by subsequent findings. For the interpretation of time-calibrated phylogenies, we discuss how the use of time-calibrated phylogenies for reconstructing general evolutionary timescales leads to inferences about macroevolution that are highly sensitive to methodological limitations in how uncertainty is accounted for. By contrast, we discuss how the use of time-calibrated phylogenies to test specific hypotheses leads to inferences about macroevolution that are less sensitive to methodological limitations. Given that many biologists wish to use time-calibrated phylogenies to reconstruct general evolutionary timescales, we conclude that the development of methods of divergence time estimation that adequately account for uncertainty is necessary.

Global classification and evolution of brushlegged mayflies (Insecta: Ephemeroptera: Oligoneuriidae): phylogenetic analyses of morphological and molecular data and dated historical biogeography

2019 ◽  
Vol 187 (2) ◽  
pp. 378-412 ◽  
Author(s):  
Fabiana Criste Massariol ◽  
Daniela Maeda Takiya ◽  
Frederico Falcão Salles
Keyword(s):  
Phylogenetic Analyses ◽  
Divergence Time ◽  
Time Estimation ◽  
Single Species ◽  
Molecular Data ◽  
Neotropical Region ◽  
Fossil Species ◽  
Divergence Time Estimation ◽  
The Family ◽  
Family Based

AbstractOligoneuriidae is a Pantropical family of Ephemeroptera, with 68 species described in 12 genera. Three subfamilies are recognized: Chromarcyinae, with a single species from East Asia; Colocrurinae, with two fossil species from Brazil; and Oligoneuriinae, with the remaining species distributed in the Neotropical, Nearctic, Afrotropical and Palaearctic regions. Phylogenetic and biogeographical analyses were performed for the family based on 2762 characters [73 morphological and 2689 molecular (COI, 16S, 18S and 28S)]. Four major groups were recovered in all analyses (parsimony, maximum likelihood and Bayesian inference), and they were assigned to tribal level, namely Oligoneuriini, Homoeoneuriini trib. nov., Oligoneuriellini trib. nov. and Elassoneuriini trib. nov. In addition, Yawari and Madeconeuria were elevated to genus level. According to Statistical Dispersal-Vicariance (S-DIVA), Dispersal Extinction Cladogenesis (DEC) and divergence time estimation analyses, Oligoneuriidae originated ~150 Mya in the Gondwanan supercontinent, but was probably restricted to the currently delimited Neotropical region. The initial divergence of Oligoneuriidae involved a range expansion to Oriental and Afrotropical areas, sometime between 150 and 118 Mya. At ~118 Mya, the family started its diversification, reaching the Nearctic through dispersal from the Neotropical region and the Palaearctic and Madagascar from the Afrotropical region.

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