Taxonomic resolution of the Tetratheca hirsuta (Elaeocarpaceae) species complex using an integrative approach

2017 ◽  
Vol 30 (1) ◽  
pp. 1 ◽  
Author(s):  
E. M. Joyce ◽  
R. Butcher ◽  
M. Byrne ◽  
P. F. Grierson ◽  
M. Hankinson ◽  
...  
Keyword(s):  
Species Complex ◽  
Incomplete Lineage Sorting ◽  
Phylogenetic Analyses ◽  
Morphological Data ◽  
Taxonomic Resolution ◽  
Integrative Approach ◽  
Gene Trees ◽  
Lineage Sorting ◽  
Molecular Phylogenetic ◽  
Slow Evolution

The Tetratheca hirsuta Lindl. species complex from south-west Western Australia is one of the last unresolved complexes in this Australian endemic genus, and comprises the highly variable T. hirsuta, two rare, phrase-named taxa, and the closely allied T. hispidissima Steetz. An integrative approach, incorporating multivariate morphometric analysis and molecular phylogenetic and phenetic analyses of nrDNA (ETS) and cpDNA (ndhF–trnL, rpl16, trnS–trnG5ʹ2S), was used to investigate taxonomic boundaries within the complex. Morphological data showed clear divergence within the complex, and allowed several taxonomically uncertain individuals to be assigned. Phenetic and phylogenetic analyses of ETS showed substantial congruence with morphology, indicating that the groups recognised through morphometric analyses are also genetically divergent. By comparison, the chloroplast regions yielded incongruent gene trees, perhaps owing to incomplete lineage sorting, hybridisation or slow evolution of cpDNA. The present results support the recognition of the following four taxa: a morphologically and geographically expanded T. hispidissima, which is highly divergent from the remainder of the complex, and a closer grouping of T. hirsuta subsp. boonanarring Joyce & R.Butcher subsp. nov., T. hirsuta subsp. viminea (Lindl.) Joyce comb. et stat. nov. and T. hirsuta subsp. hirsuta.

scholarly journals Herzog Vindicated: Integrative Taxonomy Reveals that Trichostomum brachydontium (Pottiaceae, Bryophyta) Comprises Several Species

2021 ◽  
Author(s):  
Rosa M. Ros ◽  
Olaf Werner ◽  
Ron D. Porley
Keyword(s):  
Incomplete Lineage Sorting ◽  
Phylogenetic Analyses ◽  
Integrative Taxonomy ◽  
Morphological Data ◽  
Phylogenetic Study ◽  
Lineage Sorting ◽  
New Name ◽  
Molecular Phylogenetic Study ◽  
Molecular Phylogenetic ◽  
Phylogenetic Lineages

The morphologically variable moss Trichostomum brachydontium is very common in south and west Europe, particularly under Mediterranean and Atlantic climates. A morphological study was conducted alongside a molecular phylogenetic study based on nr ITS and cp rbcL regions in order to assess if T. brachydontium is an exceptionally polymorphic species as evidenced by the number of described infraspecific taxa from the last century or, alternatively, if it includes more than one species, and if so, to find the valid name for them. Phylogenetic analyses of both nuclear and chloroplast datasets show that there are four well-supported clades. While the ITS based tree is in good agreement with the morphological data, there are a few inconsistencies with reference to the rbcL tree; this may be explained by incomplete lineage sorting or by hybridization. The morphological survey revealed well-defined discriminate differences between the four phylogenetic lineages. The taxonomic conclusions include the recognition of four species: T. brachydontium s.s., T. herzogii (a new name proposed for var. cuspidatum), T. littorale and T. meridionale (a new name proposed for var. densum). Lectotypes are designated for T. brachydontium and T. littorale. Our results underline the ongoing need of integrative studies to examine further the underestimated diversity of the T. brachydontium complex in other regions.

scholarly journals Phylogeny and Species Delimitation of Chinese Medicago (Leguminosae) and Its Relatives Based on Molecular and Morphological Evidence

2021 ◽  
Vol 11 ◽  
Author(s):  
Jinyuan Chen ◽  
Guili Wu ◽  
Nawal Shrestha ◽  
Shuang Wu ◽  
Wei Guo ◽  
...  
Keyword(s):  
Phylogenetic Relationship ◽  
Species Delimitation ◽  
Large Scale ◽  
Incomplete Lineage Sorting ◽  
Phylogenetic Analyses ◽  
Population Based ◽  
Integrative Approach ◽  
Morphological Evidence ◽  
Sampling Errors ◽  
Lineage Sorting

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.

Discovery of two ‘chimeric’ Gastrotricha and their systematic placement based on an integrative approach

2020 ◽  
Author(s):  
Alexander Kieneke ◽  
M Antonio Todaro
Keyword(s):  
Dna Sequences ◽  
New Genus ◽  
Phylogenetic Analyses ◽  
Mouth Opening ◽  
Reproductive Organs ◽  
Morphological Data ◽  
Integrative Approach ◽  
New Taxon ◽  
Linear Distance ◽  
Molecular Phylogenetic

Abstract Sublittoral sand from the islands of Sardinia (Italy) and Flores (Azores) – separated by more than 3700 km linear distance and 8 years between two independent sampling campaigns – yielded conspicuous specimens of two bizarre, yet undescribed, species of the marine gastrotrich clade Macrodasyida. These gastrotrichs combine several character traits that were already known from two, non-related genera. Morphological data were carefully analysed and digitally documented, and nuclear and mitochondrial DNA sequences were used for phylogenetic inference. The results of these analyses claim for the erection of a new genus. Specimens of the new taxon have a body length of less than 400 µm and are characterized by a wide, funnel-shaped mouth opening shielded dorsally by an oral hood and possess a posterior peduncle that ends with a Y-shaped pair of appendages that carry the posterior adhesive tubes. Further tubes occur as anterior, ventrolateral and lateral series; the gonads are unpaired and there is a set of two accessory reproductive organs. Molecular phylogenetic analyses confirm the results of former studies and clearly place the new taxon in Thaumastodermatidae. We hereby propose the establishment of Chimaeradasys gen. nov. and describe C. oligotubulatus sp. nov. from the Azores and C. polytubulatus sp. nov. from Sardinia.

scholarly journals Target enrichment improves phylogenetic resolution in the genus Zanthoxylum (Rutaceae) and indicates both incomplete lineage sorting and hybridization events

2021 ◽  
Author(s):  
Niklas Reichelt ◽  
Jun Wen ◽  
Claudia Paetzold ◽  
Marc Appelhans
Keyword(s):  
High Throughput Sequencing ◽  
Incomplete Lineage Sorting ◽  
Phylogenetic Analyses ◽  
Gene Tree ◽  
Single Copy ◽  
Reticulate Evolution ◽  
Gene Trees ◽  
Target Enrichment ◽  
Lineage Sorting ◽  
Phylogenetic Resolution

Background and aims: Zanthoxylum L. is the only pantropical genus within Rutaceae, with a few species native to temperate eastern Asia and North America. Efforts using Sanger sequencing failed to resolve the backbone phylogeny of Zanthoxylum. In this study, we employed target enrichment high-throughput sequencing to improve resolution. Gene trees were examined for concordance and sectional classifications of Zanthoxylum were evaluated. Off-target reads were investigated to identify putative single-copy markers for bait refinement, and low-copy markers for evidence of putative hybridization events. Methods: We developed a custom bait set for target enrichment of 745 exons in Zanthoxylum and applied it to 45 Zanthoxylum species and one Tetradium species as the outgroup. Illumina reads were processed via the HybPhyloMaker pipeline. Phylogenetic inferences were conducted using coalescent and concatenated methods. Concordance was assessed using quartet sampling. Off-target reads were assembled and putative single- and low-copy genes were extracted. Additional phylogenetic analyses were performed based on these alignments. Key results: Four major clades are supported within Zanthoxylum: the African clade, the Z. asiaticum clade, the Asian-Pacific-Australian clade, and the American-eastern Asian clade. While overall support has improved, regions of conflict are similar to those previously observed. Gene tree discordances indicate a hybridization event in the ancestor of the Hawaiian lineage, and incomplete lineage sorting for the American backbone. Off-target putative single-copy genes largely confirm on-target results, and putative low-copy genes provide additional evidence for hybridization in the Hawaiian lineage. Only two of the five sections of Zanthoxylum are resolved as monophyletic. Conclusion: Target enrichment is suitable to assess phylogenetic relationships in Zanthoxylum. Our phylogenetic analyses reveal that current sectional classifications need revision. Quartet tree concordance indicates several instances of reticulate evolution. Off-target reads are proven useful to identify additional phylogenetically informative regions for bait refinement or gene tree based approaches.

scholarly journals A Polynomial-Time Algorithm for Minimizing the Deep Coalescence Cost for Level-1 Species Networks

2020 ◽  
Author(s):  
Matthew LeMay ◽  
Ran Libeskind-Hadas ◽  
Yi-Chieh Wu
Keyword(s):  
Polynomial Time ◽  
Incomplete Lineage Sorting ◽  
Phylogenetic Analyses ◽  
Polynomial Time Algorithm ◽  
Time Algorithm ◽  
Phylogenetic Networks ◽  
Gene Trees ◽  
Lineage Sorting ◽  
Hybrid Species ◽  
Level 1

Phylogenetic analyses commonly assume that the species history can be represented as a tree. However, in the presence of hybridization, the species history is more accurately captured as a network. Despite several advances in modeling phylogenetic networks, there is no known polynomial-time algorithm for parsimoniously reconciling gene trees with species networks while accounting for incomplete lineage sorting. To address this issue, we present a polynomial-time algorithm for the case of level-1 networks, in which no hybrid species is the direct ancestor of another hybrid species. This work enables more efficient reconciliation of gene trees with species networks, which in turn, enables more efficient reconstruction of species networks.

scholarly journals Disentangling relationships among eastern Mediterranean Cymbalaria including description of a novel species from the southern Peloponnese (Greece)

2021 ◽  
Vol 307 (2) ◽  
Author(s):  
Pau Carnicero ◽  
Núria Garcia-Jacas ◽  
Llorenç Sáez ◽  
Theophanis Constantinidis ◽  
Mercè Galbany-Casals
Keyword(s):  
Eastern Mediterranean ◽  
Phylogenetic Analyses ◽  
Taxonomic Revision ◽  
Distribution Patterns ◽  
Morphological Characters ◽  
Molecular Data ◽  
Morphological Data ◽  
Long Distance ◽  
Aegean Islands ◽  
Molecular Phylogenetic

AbstractThe eastern Mediterranean basin hosts a remarkably high plant diversity. Historical connections between currently isolated areas across the Aegean region and long-distance dispersal events have been invoked to explain current distribution patterns of species. According to most recent treatments, at least two Cymbalaria species occur in this area, Cymbalaria microcalyx and C. longipes. The former comprises several intraspecific taxa, treated at different ranks by different authors based on morphological data, evidencing the need of a taxonomic revision. Additionally, some populations of C. microcalyx show exclusive morphological characters that do not match any described taxon. Here, we aim to shed light on the systematics of eastern Mediterranean Cymbalaria and to propose a classification informed by various sources of evidence. We performed molecular phylogenetic analyses using ITS, 3’ETS, ndhF and rpl32-trnL sequences and estimated the ploidy level of some taxa performing relative genome size measures. Molecular data combined with morphology support the division of traditionally delimited C. microcalyx into C. acutiloba, C. microcalyx and C. minor, corresponding to well-delimited nrDNA lineages. Furthermore, we propose to combine C. microcalyx subsp. paradoxa at the species level. A group of specimens previously thought to belong to Cymbalaria microcalyx constitute a well-defined phylogenetic and morphological entity and are described here as a new species, Cymbalaria spetae. Cymbalaria longipes is non-monophyletic, but characterized by being glabrous and diploid, unlike other eastern species. The nrDNA data suggest at least two dispersals from the mainland to the Aegean Islands, potentially facilitated by marine regressions.

scholarly journals Phylogenomic Discordance in the Eared Seals is best explained by Incomplete Lineage Sorting following Explosive Radiation in the Southern Hemisphere

2020 ◽  
Author(s):  
Fernando Lopes ◽  
Larissa R Oliveira ◽  
Amanda Kessler ◽  
Yago Beux ◽  
Enrique Crespo ◽  
...  
Keyword(s):  
Incomplete Lineage Sorting ◽  
Gene Tree ◽  
Molecular Data ◽  
Species Tree ◽  
Gene Trees ◽  
Lineage Sorting ◽  
Data Types ◽  
High Coverage ◽  
Sea Lions ◽  
The Family

Abstract The phylogeny and systematics of fur seals and sea lions (Otariidae) have long been studied with diverse data types, including an increasing amount of molecular data. However, only a few phylogenetic relationships have reached acceptance because of strong gene-tree species tree discordance. Divergence times estimates in the group also vary largely between studies. These uncertainties impeded the understanding of the biogeographical history of the group, such as when and how trans-equatorial dispersal and subsequent speciation events occurred. Here we used high-coverage genome-wide sequencing for 14 of the 15 species of Otariidae to elucidate the phylogeny of the family and its bearing on the taxonomy and biogeographical history. Despite extreme topological discordance among gene trees, we found a fully supported species tree that agrees with the few well-accepted relationships and establishes monophyly of the genus Arctocephalus. Our data support a relatively recent trans-hemispheric dispersal at the base of a southern clade, which rapidly diversified into six major lineages between 3 to 2.5 Ma. Otaria diverged first, followed by Phocarctos and then four major lineages within Arctocephalus. However, we found Zalophus to be non-monophyletic, with California (Z. californianus) and Steller sea lions (Eumetopias jubatus) grouping closer than the Galapagos sea lion (Z. wollebaeki) with evidence for introgression between the two genera. Overall, the high degree of genealogical discordance was best explained by incomplete lineage sorting resulting from quasi-simultaneous speciation within the southern clade with introgresssion playing a subordinate role in explaining the incongruence among and within prior phylogenetic studies of the family.

scholarly journals Impact of Ghost Introgression on Coalescent-based Species Tree Inference and Estimation of Divergence Time

2022 ◽  
Author(s):  
XiaoXu Pang ◽  
Da-Yong Zhang
Keyword(s):  
Incomplete Lineage Sorting ◽  
Divergence Time ◽  
Species Tree ◽  
Gene Trees ◽  
Species Trees ◽  
Lineage Sorting ◽  
Multispecies Coalescent ◽  
Tree Inference ◽  
Tree Methods ◽  
The Impact

The species studied in any evolutionary investigation generally constitute a very small proportion of all the species currently existing or that have gone extinct. It is therefore likely that introgression, which is widespread across the tree of life, involves "ghosts," i.e., unsampled, unknown, or extinct lineages. However, the impact of ghost introgression on estimations of species trees has been rarely studied and is thus poorly understood. In this study, we use mathematical analysis and simulations to examine the robustness of species tree methods based on a multispecies coalescent model under gene flow sourcing from an extant or ghost lineage. We found that very low levels of extant or ghost introgression can result in anomalous gene trees (AGTs) on three-taxon rooted trees if accompanied by strong incomplete lineage sorting (ILS). In contrast, even massive introgression, with more than half of the recipient genome descending from the donor lineage, may not necessarily lead to AGTs. In cases involving an ingroup lineage (defined as one that diverged no earlier than the most basal species under investigation) acting as the donor of introgression, the time of root divergence among the investigated species was either underestimated or remained unaffected, but for the cases of outgroup ghost lineages acting as donors, the divergence time was generally overestimated. Under many conditions of ingroup introgression, the stronger the ILS was, the higher was the accuracy of estimating the time of root divergence, although the topology of the species tree is more prone to be biased by the effect of introgression.

scholarly journals How to Tackle Phylogenetic Discordance in Recent and Rapidly Radiating Groups? Developing a Workflow Using Loricaria (Asteraceae) as an Example

2022 ◽  
Vol 12 ◽  
Author(s):  
Martha Kandziora ◽  
Petr Sklenář ◽  
Filip Kolář ◽  
Roswitha Schmickl
Keyword(s):  
Incomplete Lineage Sorting ◽  
Gene Tree ◽  
Species Tree ◽  
Secondary Contact ◽  
Gene Trees ◽  
Species Trees ◽  
Lineage Sorting ◽  
Phylogenetic Discordance ◽  
Gene Tree Discordance ◽  
High Degree

A major challenge in phylogenetics and -genomics is to resolve young rapidly radiating groups. The fast succession of species increases the probability of incomplete lineage sorting (ILS), and different topologies of the gene trees are expected, leading to gene tree discordance, i.e., not all gene trees represent the species tree. Phylogenetic discordance is common in phylogenomic datasets, and apart from ILS, additional sources include hybridization, whole-genome duplication, and methodological artifacts. Despite a high degree of gene tree discordance, species trees are often well supported and the sources of discordance are not further addressed in phylogenomic studies, which can eventually lead to incorrect phylogenetic hypotheses, especially in rapidly radiating groups. We chose the high-Andean Asteraceae genus Loricaria to shed light on the potential sources of phylogenetic discordance and generated a phylogenetic hypothesis. By accounting for paralogy during gene tree inference, we generated a species tree based on hundreds of nuclear loci, using Hyb-Seq, and a plastome phylogeny obtained from off-target reads during target enrichment. We observed a high degree of gene tree discordance, which we found implausible at first sight, because the genus did not show evidence of hybridization in previous studies. We used various phylogenomic analyses (trees and networks) as well as the D-statistics to test for ILS and hybridization, which we developed into a workflow on how to tackle phylogenetic discordance in recent radiations. We found strong evidence for ILS and hybridization within the genus Loricaria. Low genetic differentiation was evident between species located in different Andean cordilleras, which could be indicative of substantial introgression between populations, promoted during Pleistocene glaciations, when alpine habitats shifted creating opportunities for secondary contact and hybridization.

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