| 1. |
- Hernández-Ledesma, P., et al.
(författare)
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A taxonomic backbone for the global synthesis of species diversity in the angiosperm order Caryophyllales
- 2015
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Ingår i: Willdenowia. - : Botanic Garden and Botanical Museum Berlin, Freie Universitaet Berlin. - 0511-9618 .- 1868-6397. ; 45:3, s. 281-383
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Tidskriftsartikel (refereegranskat)abstract
- The Caryophyllales constitute a major lineage of flowering plants with approximately 12500 species in 39 families. A taxonomic backbone at the genus level is provided that reflects the current state of knowledge and accepts 749 genera for the order. A detailed review of the literature of the past two decades shows that enormous progress has been made in understanding overall phylogenetic relationships in Caryophyllales. The process of re-circumscribing families in order to be monophyletic appears to be largely complete and has led to the recognition of eight new families (Anacampserotaceae, Kewaceae, Limeaceae, Lophiocarpaceae, Macarthuriaceae, Microteaceae, Montiaceae and Talinaceae), while the phylogenetic evaluation of generic concepts is still well underway. As a result of this, the number of genera has increased by more than ten percent in comparison to the last complete treatments in the Families and genera of vascular plants” series. A checklist with all currently accepted genus names in Caryophyllales, as well as nomenclatural references, type names and synonymy is presented. Notes indicate how extensively the respective genera have been studied in a phylogenetic context. The most diverse families at the generic level are Cactaceae and Aizoaceae, but 28 families comprise only one to six genera. This synopsis represents a first step towards the aim of creating a global synthesis of the species diversity in the angiosperm order Caryophyllales integrating the work of numerous specialists around the world.
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| 2. |
- Alström, Per, Professor, et al.
(författare)
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Multiple species delimitation approaches applied to the avian lark genus Alaudala
- 2021
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 154
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Tidskriftsartikel (refereegranskat)abstract
- Species delimitation has advanced from a purely phenotypic exercise to a branch of science that integrates multiple sources of data to identify independently evolving lineages that can be treated as species. We here test species limits in the avian Lesser Short-toed Lark Alaudala rufesens-Sand Lark A. raytal complex, which has an intricate taxonomic history, ranging from a single to three recognised species, with different inclusiveness in different treatments. Our integrative taxonomic approach is based on a combination of DNA sequences, plumage, biometrics, songs, song-flights, geographical distributions, habitat, and bioclimatic data, and using various methods including a species delimitation program (STACEY) based on the multispecies coalescent model. We propose that four species should be recognised: Lesser Short-toed Lark A. rufescens (sensu stricto), Heine's Short-toed Lark A. heinei, Asian Short-toed Lark A. cheleensis and Sand Lark A. raytal. There is also some evidence suggesting lineage separation within A. cheleensis and A. raytal, but additional data are required to evaluate this. The species delimitation based on STACEY agrees well with the non-genetic data. Although computer-based species delimitation programs can be useful in identifying independently evolving lineages, we stress that whenever possible, species hypotheses proposed by these programs should be tested by independent, non-genetic data. Our results highlight the difficulty and subjectivity of delimiting lineages and species, especially at early stages in the speciation process.
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| 3. |
- Andermann, Tobias, et al.
(författare)
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A Guide to Carrying Out a Phylogenomic Target Sequence Capture Project
- 2020
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Ingår i: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- High-throughput DNA sequencing techniques enable time- and cost-effective sequencing of large portions of the genome. Instead of sequencing and annotating whole genomes, many phylogenetic studies focus sequencing effort on large sets of pre-selected loci, which further reduces costs and bioinformatic challenges while increasing coverage. One common approach that enriches loci before sequencing is often referred to as target sequence capture. This technique has been shown to be applicable to phylogenetic studies of greatly varying evolutionary depth. Moreover, it has proven to produce powerful, large multi-locus DNA sequence datasets suitable for phylogenetic analyses. However, target capture requires careful considerations, which may greatly affect the success of experiments. Here we provide a simple flowchart for designing phylogenomic target capture experiments. We discuss necessary decisions from the identification of target loci to the final bioinformatic processing of sequence data. We outline challenges and solutions related to the taxonomic scope, sample quality, and available genomic resources of target capture projects. We hope this review will serve as a useful roadmap for designing and carrying out successful phylogenetic target capture studies.
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| 4. |
- Andermann, Tobias, et al.
(författare)
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Allele Phasing Greatly Improves the Phylogenetic Utility of Ultraconserved Elements
- 2019
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Ingår i: Systematic Biology. - : Oxford University Press (OUP). - 1063-5157 .- 1076-836X. ; 68:1, s. 32-46
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Tidskriftsartikel (refereegranskat)abstract
- Advances in high-throughput sequencing techniques now allow relatively easy and affordable sequencing of large portions of the genome, even for nonmodel organisms. Many phylogenetic studies reduce costs by focusing their sequencing efforts on a selected set of targeted loci, commonly enriched using sequence capture. The advantage of this approach is that it recovers a consistent set of loci, each with high sequencing depth, which leads to more confidence in the assembly of target sequences. High sequencing depth can also be used to identify phylogenetically informative allelic variation within sequenced individuals, but allele sequences are infrequently assembled in phylogenetic studies. Instead, many scientists perform their phylogenetic analyses using contig sequences which result from the de novo assembly of sequencing reads into contigs containing only canonical nucleobases, and this may reduce both statistical power and phylogenetic accuracy. Here, we develop an easy-to-use pipeline to recover allele sequences from sequence capture data, and we use simulated and empirical data to demonstrate the utility of integrating these allele sequences to analyses performed under the multispecies coalescent model. Our empirical analyses of ultraconserved element locus data collected from the South American hummingbird genus Topaza demonstrate that phased allele sequences carry sufficient phylogenetic information to infer the genetic structure, lineage divergence, and biogeographic history of a genus that diversified during the last 3 myr. The phylogenetic results support the recognition of two species and suggest a high rate of gene flow across large distances of rainforest habitats but rare admixture across the Amazon River. Our simulations provide evidence that analyzing allele sequences leads to more accurate estimates of tree topology and divergence times than the more common approach of using contig sequences.
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| 5. |
- Antonelli, Alexandre, 1978, et al.
(författare)
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Embracing heterogeneity: Coalescing the tree of life and the future of phylogenomics
- 2019
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 2019:2
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Tidskriftsartikel (refereegranskat)abstract
- Building the Tree of Life (ToL) is a major challenge of modern biology, requiring advances in cyberinfrastructure, data collection, theory, and more. Here, we argue that phylogenomics stands to benefit by embracing the many heterogeneous genomic signals emerging from the first decade of large-scale phylogenetic analysis spawned by high-throughput sequencing (HTS). Such signals include those most commonly encountered in phylogenomic datasets, such as incomplete lineage sorting, but also those reticulate processes emerging with greater frequency, such as recombination and introgression. Here we focus specifically on how phylogenetic methods can accommodate the heterogeneity incurred by such population genetic processes; we do not discuss phylogenetic methods that ignore such processes, such as concatenation or supermatrix approaches or supertrees. We suggest that methods of data acquisition and the types of markers used in phylogenomics will remain restricted until a posteriori methods of marker choice are made possible with routine whole-genome sequencing of taxa of interest. We discuss limitations and potential extensions of a model supporting innovation in phylogenomics today, the multispecies coalescent model (MSC). Macroevolutionary models that use phylogenies, such as character mapping, often ignore the heterogeneity on which building phylogenies increasingly rely and suggest that assimilating such heterogeneity is an important goal moving forward. Finally, we argue that an integrative cyberinfrastructure linking all steps of the process of building the ToL, from specimen acquisition in the field to publication and tracking of phylogenomic data, as well as a culture that values contributors at each step, are essential for progress.
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| 6. |
- Antonelli, Alexandre, 1978, et al.
(författare)
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SUPERSMART: ecology and evolution in the era of big data
- 2014
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Ingår i: PeerJ PrePrints. - : PeerJ. - 2167-9843.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Rapidly growing biological data volumes – including molecular sequences, species traits, geographic occurrences, specimen collections, and fossil records – hold an unprecedented, yet largely unexplored potential to reveal how ecological and evolutionary processes generate and maintain biodiversity. Most biodiversity studies integrating ecological data and evolutionary history use an idiosyncratic step-by-step approach for the reconstruction of time-calibrated phylogenies in light of ecological and evolutionary scenarios. Here we introduce a conceptual framework, termed SUPERSMART (Self-Updating Platform for Estimating Rates of Speciation and Migration, Ages, and Relationships of Taxa), and provide a proof of concept for dealing with the moving targets of biodiversity research. This framework reconstructs dated phylogenies based on the assembly of molecular datasets and collects pertinent data on ecology, distribution, and fossils of the focal clade. The data handled for each step are continuously updated as databases accumulate new records. We exemplify the practice of our method by presenting comprehensive phylogenetic and dating analyses for the orders Primates and the Gentianales. We believe that this emerging framework will provide an invaluable tool for a wide range of hypothesis-driven research questions in ecology and evolution.
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| 7. |
- Antonelli, Alexandre, 1978, et al.
(författare)
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Toward a Self-Updating Platform for Estimating Rates of Speciation and Migration, Ages, and Relationships of Taxa.
- 2017
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Ingår i: Systematic biology. - : Oxford University Press (OUP). - 1076-836X .- 1063-5157. ; 66:2, s. 152-166
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Tidskriftsartikel (refereegranskat)abstract
- Rapidly growing biological data-including molecular sequences and fossils-hold an unprecedented potential to reveal how evolutionary processes generate and maintain biodiversity. However, researchers often have to develop their own idiosyncratic workflows to integrate and analyze these data for reconstructing time-calibrated phylogenies. In addition, divergence times estimated under different methods and assumptions, and based on data of various quality and reliability, should not be combined without proper correction. Here we introduce a modular framework termed SUPERSMART (Self-Updating Platform for Estimating Rates of Speciation and Migration, Ages, and Relationships of Taxa), and provide a proof of concept for dealing with the moving targets of evolutionary and biogeographical research. This framework assembles comprehensive data sets of molecular and fossil data for any taxa and infers dated phylogenies using robust species tree methods, also allowing for the inclusion of genomic data produced through next-generation sequencing techniques. We exemplify the application of our method by presenting phylogenetic and dating analyses for the mammal order Primates and for the plant family Arecaceae (palms). We believe that this framework will provide a valuable tool for a wide range of hypothesis-driven research questions in systematics, biogeography, and evolution. SUPERSMART will also accelerate the inference of a "Dated Tree of Life" where all node ages are directly comparable. [Bayesian phylogenetics; data mining; divide-and-conquer methods; GenBank; multilocus multispecies coalescent; next-generation sequencing; palms; primates; tree calibration.].
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| 8. |
- Aydin, Zeynep, et al.
(författare)
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A new section of Silene (Caryophyllaceae) including a new species from South Anatolia, Turkey
- 2014
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Ingår i: Phytotaxa. - : Magnolia Press. - 1179-3155 .- 1179-3163. ; 178:2, s. 98-112
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Tidskriftsartikel (refereegranskat)abstract
- Silene section Cryptoneurae (Caryophyllaceae) and S. ertekinii from Western Antalya, Turkey, are described as new taxa on the basis of morphological and molecular investigations. Nuclear ITS and chloroplast rps16 DNA sequences clearly support the recognition of the new section. Inclusiveness and characterization of the new section is discussed and described, and a key for the included species is provided. Diagnostic characters of the new species S. ertekinii are given and its relation to the other species of the section is discussed.
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| 9. |
- Aydin, Zeynep, et al.
(författare)
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Marginal Likelihood Estimate Comparisons to Obtain Optimal Species Delimitations in Silene sect. Cryptoneurae (Caryophyllaceae)
- 2014
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 9:9
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Tidskriftsartikel (refereegranskat)abstract
- Coalescent-based inference of phylogenetic relationships among species takes into account gene tree incongruence due to incomplete lineage sorting, but for such methods to make sense species have to be correctly delimited. Because alternative assignments of individuals to species result in different parametric models, model selection methods can be applied to optimise model of species classification. In a Bayesian framework, Bayes factors (BF), based on marginal likelihood estimates, can be used to test a range of possible classifications for the group under study. Here, we explore BF and the Akaike Information Criterion (AIC) to discriminate between different species classifications in the flowering plant lineage Silene sect. Cryptoneurae (Caryophyllaceae). We estimated marginal likelihoods for different species classification models via the Path Sampling (PS), Stepping Stone sampling (SS), and Harmonic Mean Estimator (HME) methods implemented in BEAST. To select among alternative species classification models a posterior simulation-based analog of the AIC through Markov chain Monte Carlo analysis (AICM) was also performed. The results are compared to outcomes from the software BP&P. Our results agree with another recent study that marginal likelihood estimates from PS and SS methods are useful for comparing different species classifications, and strongly support the recognition of the newly described species S. ertekinii.
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| 10. |
- Bacon, Christine D., et al.
(författare)
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Evolutionary persistence in Gunnera and the contribution of southern plant groups to the tropical Andes biodiversity hotspot
- 2018
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 2018:3
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Tidskriftsartikel (refereegranskat)abstract
- Several studies have demonstrated the contribution of northern immigrants to the flora of the tropical Andesthe world's richest and most diverse biodiversity hotspot. However, much less is known about the biogeographic history and diversification of Andean groups with southern origins, although it has been suggested that northern and southern groups have contributed roughly equally to the high Andean (i.e., páramo) flora. Here we infer the evolutionary history of the southern hemisphere plant genus Gunnera, a lineage with a rich fossil history and an important ecological role as an early colonising species characteristic of wet, montane environments. Our results show striking contrasts in species diversification, where some species may have persisted for some 90 million years, and whereas others date to less than 2 Ma since origination. The outstanding longevity of the group is likely linked to a high degree of niche conservatism across its highly disjunct range, whereby Gunnera tracks damp and boggy soils in cool habitats. Colonisation of the northern Andes is related to Quaternary climate change, with subsequent rapid diversification appearing to be driven by their ability to take advantage of environmental opportunities. This study demonstrates the composite origin of a mega-diverse biota.
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| 11. |
- Balounova, V., et al.
(författare)
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Evolution of sex determination and heterogamety changes in section Otites of the genus Silene
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Switches in heterogamety are known to occur in both animals and plants. Although plant sex determination systems probably often evolved more recently than those in several well-studied animals, including mammals, and have had less time for switches to occur, we previously detected a switch in heterogamety in the plant genus Silene: section Otites has both female and male heterogamety, whereas S. latifolia and its close relatives, in a different section of the genus, Melandrium (subgenus Behenantha), all have male heterogamety. Here we analyse the evolution of sex chromosomes in section Otites, which is estimated to have evolved only about 0.55 MYA. Our study confirms female heterogamety in S. otites and newly reveals female heterogamety in S. borysthenica. Sequence analyses and genetic mapping show that the sex-linked regions of these two species are the same, but the region in S. colpophylla, a close relative with male heterogamety, is different. The sex chromosome pairs of S. colpophylla and S. otites each correspond to an autosome of the other species, and both differ from the XY pair in S. latifolia. Silene section Otites species are suitable for detailed studies of the events involved in such changes, and our phylogenetic analysis suggests a possible change from female to male heterogamety within this section. Our analyses suggest a possibility that has so far not been considered, change in heterogamety through hybridization, in which a male-determining chromosome from one species is introgressed into another one, and over-rides its previous sex-determining system.
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| 12. |
- Bartoszek, Krzysztof, 1984-, et al.
(författare)
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Time to a single hybridization event in a group of species with unknown ancestral history
- 2013
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Ingår i: Journal of Theoretical Biology. - : Elsevier BV. - 0022-5193 .- 1095-8541. ; 322, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- We consider a stochastic process for the generation of species which combines a Yule process with a simple model for hybridization between pairs of co-existent species. We assume that the origin of the process, when there was one species, occurred at an unknown time in the past, and we condition the process on producing n species via the Yule process and a single hybridization event. We prove results about the distribution of the time of the hybridization event. In particular we calculate a formula for all moments, and show that under various conditions, the distribution tends to an exponential with rate twice that of the birth rate for the Yule process.
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| 13. |
- Bertrand, Yann, et al.
(författare)
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Assignment of homoeologues to parental genomes in allopolyploids for species tree inference, with an example from Fumaria (Papaveraceae)
- 2015
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Ingår i: Systematic Biology. - : Oxford University Press (OUP). - 1063-5157 .- 1076-836X. ; 64:3, s. 448-471
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Tidskriftsartikel (refereegranskat)abstract
- There is a rising awareness that species trees are best inferred from multiple loci while taking into account processes affecting individual gene trees, such as substitution model error (failure of the model to account for the complexity of the data) and coalescent stochasticity (presence of incomplete lineage sorting). Although most studies have been carried out in the context of dichotomous species trees, these processes operate also in more complex evolutionary histories involving multiple hybridizations and polyploidy. Recently, methods have been developed that accurately handle incomplete lineage sorting in allopolyploids, but they are thus far restricted to networks of diploids and tetraploids. We propose a procedure that improves on this limitation by designing a workflow that assigns homoeologues to hypothetical diploid ancestral genomes prior to genome tree construction. Conflicting assignment hypotheses are evaluated against substitution model error and coalescent stochasticity. Incongruence that cannot be explained by stochastic mechanisms needs to be explained by other processes (e.g., homoploid hybridization or paralogy). The data can then be filtered to build multilabeled genome phylogenies using inference methods that can recover species trees, either in the face of substitution model error and coalescent stochasticity alone, or while simultaneously accounting for hybridization. Methods are already available for folding the resulting multilabeled genome phylogeny into a network. We apply the workflow to the reconstruction of the reticulate phylogeny of the plant genus Fumaria (Papaveraceae) with ploidal levels ranging from 2x to 14x. We describe the challenges in recovering nuclear NRPB2 homoeologues in high ploidy species while combining in vivo cloning and direct sequencing techniques. Using parametric bootstrapping simulations we assign nuclear homoeologues and chloroplast sequences (four concatenated loci) to their common hypothetical diploid ancestral genomes. As these assignments hinge on effective population size assumptions, we investigate how varying these assumptions impacts the recovered multilabeled genome phylogeny.
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| 14. |
- Brysting, A. K., et al.
(författare)
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Untangling complex histories of genome mergings in high polyploids
- 2007
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Ingår i: Systematic Biology. - : Oxford University Press (OUP). - 1063-5157 .- 1076-836X. ; 56:3, s. 467-476
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Tidskriftsartikel (refereegranskat)abstract
- Polyploidy, the duplication of entire genomes, plays a major role in plant evolution. In allopolyploids, genome duplication is associated with hybridization between two or more divergent genomes. Successive hybridization and polyploidization events can build up species complexes of allopolyploids with complicated network-like histories, and the evolutionary history of many plant groups cannot be adequately represented by phylogenetic trees because of such reticulate events. The history of complex genome mergings within a high-polyploid species complex in the genus Cerastium (Caryophyllaceae) is here untangled by the use of a network algorithm and noncoding sequences of a low-copy number gene. The resulting network illustrates how hybridization and polyploidization have acted as key evolutionary processes in creating a plant group where high-level allopolyploids clearly outnumber extant parental genomes.
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| 15. |
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| 16. |
- Eggens, Frida, et al.
(författare)
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Phylogeny and species delimitation in Silene sect. Arenosae (Caryophyllaceae): a new section
- 2020
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Ingår i: Phytokeys. - : Pensoft Publishers. - 1314-2011 .- 1314-2003. ; :159, s. 1-34
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Tidskriftsartikel (refereegranskat)abstract
- A putatively monophyletic group of annual Silene species is revised taxonomically and described as the new section S. sect. Arenosae. The species of this section were previously treated as a part of a widely circumscribed and polyphyletic S. sect. Rigidulae. Silene sect. Arenosae as circumscribed here consists of nine species. Members of the section show a predominantly E Mediterranean to SW Asian distribution pattern from Turkey southward to Egypt and eastward to Iran and Pakistan, although most of the species have a limited distribution range. The species of S. sect. Arenosae are characterized by narrowly lanceolate calyx teeth, which are often highly polymorphic, and lanceolate to oblanceolate (non-spathulate) basal leaves. The provided taxonomic revision is based on morphological characters and supported by phylogenetic analyses of two nuclear loci (nrITS and an intron of the RPB2 gene) and one chloroplast locus (the intron of the rps16 gene). The species descriptions are formalized using a novel implementation of the Prometheus Description Model.
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| 17. |
- Eggens, F., et al.
(författare)
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The origin and number of introductions of the Hawaiian endemic Silene species (Caryophyllaceae)
- 2007
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Ingår i: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 94:2, s. 210-218
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Tidskriftsartikel (refereegranskat)abstract
- The Hawaiian endemic Silene are a small group of woody or semiwoody representatives from a large, predominantly herbaceous, species-rich genus. We here investigated the origin and number of introductions of the endemic Hawaiian Silene based on phylogenetic relationships inferred from DNA sequences from both the plastid (the rps16 intron) and the nuclear (ribosomal internal transcribed sequences, ITS, and intron 23 of the RPB2 gene) genomes. Silene antirrhina, a widespread weedy American annual, is strongly supported as sister to a monophyletic group consisting of the Hawaiian Silene, indicating a single colonization event. There are no obvious morphological similarities between S. antirrhina and any of the species of Hawaiian Silene. Our results suggest an American origin for the Hawaiian endemics because that would require only a single trans-ocean dispersal. Two of the Hawaiian endemics (S. struthioloides and S. hawaiiensis) that form a subclade in the analyses have evolved woodiness after introduction to the Hawaiian Islands. Our results contribute to other recent results based on molecular phylogenetics that emphasize the American continent as a source area for the Hawaiian flora and support a striking morphological radiation and evolution of woodiness from a single introduction to the archipelago.
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| 18. |
- Eriksson, Jonna S., 1989, et al.
(författare)
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Allele phasing is critical to revealing a shared allopolyploid origin of Medicago arborea and M. strasseri (Fabaceae)
- 2018
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Whole genome duplication plays a central role in plant evolution. There are two main classes of polyploid formation: autopolyploids which arise within one species by doubling of similar homologous genomes; in contrast, allopolyploidy (hybrid polyploidy) arise via hybridization and subsequent doubling of nonhomologous (homoeologous) genomes. The distinction between polyploid origins can be made using gene phylogenies, if alleles from each genome can be correctly retrieved. We examined whether two closely related tetraploid Mediterranean shrubs (Medicago arborea and M. strasseri) have an allopolyploid origin - a question that has remained unsolved despite substantial previous research. We sequenced and analyzed ten low-copy nuclear genes from these and related species, phasing all alleles. To test the efficacy of allele phasing on the ability to recover the evolutionary origin of polyploids, we compared these results to analyses using unphased sequences. Results: In eight of the gene trees the alleles inferred from the tetraploids formed two clades, in a non-sister relationship. Each of these clades was more closely related to alleles sampled from other species of Medicago, a pattern typical of allopolyploids. However, we also observed that alleles from one of the remaining genes formed two clades that were sister to one another, as is expected for autopolyploids. Trees inferred from unphased sequences were very different, with the tetraploids often placed in poorly supported and different positions compared to results obtained using phased alleles. Conclusions: The complex phylogenetic history of M. arborea and M. strasseri is explained predominantly by shared allotetraploidy. We also observed that an increase in woodiness is correlated with polyploidy in this group of species and present a new possibility that woodiness could be a transgressive phenotype. Correctly phased homoeologues are likely to be critical for inferring the hybrid origin of allopolyploid species, when most genes retain more than one homoeologue. Ignoring homoeologous variation by merging the homoeologues can obscure the signal of hybrid polyploid origins and produce inaccurate results. © 2018 The Author(s).
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| 19. |
- Eriksson, J. S., et al.
(författare)
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Gene count from target sequence capture places three whole genome duplication events in Hibiscus L. (Malvaceae)
- 2021
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Ingår i: BMC Ecology and Evolution. - : Springer Science and Business Media LLC. - 1472-6785 .- 2730-7182. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The great diversity in plant genome size and chromosome number is partly due to polyploidization (i.e. genome doubling events). The differences in genome size and chromosome number among diploid plant species can be a window into the intriguing phenomenon of past genome doubling that may be obscured through time by the process of diploidization. The genus Hibiscus L. (Malvaceae) has a wide diversity of chromosome numbers and a complex genomic history. Hibiscus is ideal for exploring past genomic events because although two ancient genome duplication events have been identified, more are likely to be found due to its diversity of chromosome numbers. To reappraise the history of whole-genome duplication events in Hibiscus, we tested three alternative scenarios describing different polyploidization events. Results: Using target sequence capture, we designed a new probe set for Hibiscus and generated 87 orthologous genes from four diploid species. We detected paralogues in > 54% putative single-copy genes. 34 of these genes were selected for testing three different genome duplication scenarios using gene counting. All species of Hibiscus sampled shared one genome duplication with H. syriacus, and one whole genome duplication occurred along the branch leading to H. syriacus. Conclusions: Here, we corroborated the independent genome doubling previously found in the lineage leading to H. syriacus and a shared genome doubling of this lineage and the remainder of Hibiscus. Additionally, we found a previously undiscovered genome duplication shared by the /Pavonia and /Malvaviscus clades (both nested within Hibiscus) with the occurrences of two copies in what were otherwise single-copy genes. Our results highlight the complexity of genomic diversity in some plant groups, which makes orthology assessment and accurate phylogenomic inference difficult. © 2021, The Author(s).
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| 20. |
- Erixon, Per, et al.
(författare)
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Reticulate or treelike chloroplast DNA evolution in Sileneae (Caryophyllaceae)?
- 2008
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 48:1, s. 313-325
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Tidskriftsartikel (refereegranskat)abstract
- Despite sampling of up to 25 kb of chloroplast DNA sequence from 24 species in Sileneae a number of nodes in the phylogeny remain poorly supported and it is not expected that additional sequence sampling will converge to a reliable phylogenetic hypothesis in these parts of the tree. The main reason for this is probably a combination of rapid radiation and substitution rate heterogeneity. Poor resolution among closely related species are often explained by low levels of variation in chloroplast data, but the problem with our data appear to be high levels of homoplasy. Tree-like cpDNA evolution cannot be rejected, but apparent incongruent patterns between different regions are evaluated with the possibility of ancient interspecific chloroplast recombination as explanatory model. However, several major phylogenetic relationships, previously not recognized, are confidently resolved, e.g. the grouping of the two SW Anatolian taxa S. cryptoneura and S. sordida strongly disagrees with previous studies on nuclear DNA sequence data, and indicate a possible case of homoploid hybrid origin. The closely related S. atocioides and S. aegyptiaca form a sister group to Lychnis and the rest of Silene, thus suggesting that Silene may be paraphyletic, despite recent revisions based on molecular data.
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| 21. |
- Erixon, Per, 1972, et al.
(författare)
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Whole-gene positive selection, elevated synonymous substitution rates, duplication, and indel evolution of the chloroplast clpP1 gene.
- 2008
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Synonymous DNA substitution rates in the plant chloroplast genome are generally relatively slow and lineage dependent. Non-synonymous rates are usually even slower due to purifying selection acting on the genes. Positive selection is expected to speed up non-synonymous substitution rates, whereas synonymous rates are expected to be unaffected. Until recently, positive selection has seldom been observed in chloroplast genes, and large-scale structural rearrangements leading to gene duplications are hitherto supposed to be rare. METHODOLOGY/PRINCIPLE FINDINGS: We found high substitution rates in the exons of the plastid clpP1 gene in Oenothera (the Evening Primrose family) and three separate lineages in the tribe Sileneae (Caryophyllaceae, the Carnation family). Introns have been lost in some of the lineages, but where present, the intron sequences have substitution rates similar to those found in other introns of their genomes. The elevated substitution rates of clpP1 are associated with statistically significant whole-gene positive selection in three branches of the phylogeny. In two of the lineages we found multiple copies of the gene. Neighboring genes present in the duplicated fragments do not show signs of elevated substitution rates or positive selection. Although non-synonymous substitutions account for most of the increase in substitution rates, synonymous rates are also markedly elevated in some lineages. Whereas plant clpP1 genes experiencing negative (purifying) selection are characterized by having very conserved lengths, genes under positive selection often have large insertions of more or less repetitive amino acid sequence motifs. CONCLUSIONS/SIGNIFICANCE: We found positive selection of the clpP1 gene in various plant lineages to correlated with repeated duplication of the clpP1 gene and surrounding regions, repetitive amino acid sequences, and increase in synonymous substitution rates. The present study sheds light on the controversial issue of whether negative or positive selection is to be expected after gene duplications by providing evidence for the latter alternative. The observed increase in synonymous substitution rates in some of the lineages indicates that the detection of positive selection may be obscured under such circumstances. Future studies are required to explore the functional significance of the large inserted repeated amino acid motifs, as well as the possibility that synonymous substitution rates may be affected by positive selection.
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| 22. |
- Fior, Simone, et al.
(författare)
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Spatiotemporal reconstruction of the Aquilegia rapid radiation through next-generation sequencing of rapidly evolving cpDNA regions.
- 2013
-
Ingår i: The New phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 198:2, s. 579-92
-
Tidskriftsartikel (refereegranskat)abstract
- Aquilegia is a well-known model system in the field of evolutionary biology, but obtaining a resolved and well-supported phylogenetic reconstruction for the genus has been hindered by its recent and rapid diversification. Here, we applied 454 next-generation sequencing to PCR amplicons of 21 of the most rapidly evolving regions of the plastome to generate c. 24 kb of sequences from each of 84 individuals from throughout the genus. The resulting phylogeny has well-supported resolution of the main lineages of the genus, although recent diversification such as in the European taxa remains unresolved. By producing a chronogram of the whole Ranunculaceae family based on published data, we inferred calibration points for dating the Aquilegia radiation. The genus originated in the upper Miocene c. 6.9 million yr ago (Ma) in Eastern Asia, and diversification occurred c. 4.8 Ma with the split of two main clades, one colonizing North America, and the other Western Eurasia through the mountains of Central Asia. This was followed by a back-to-Asia migration, originating from the European stock using a North Asian route. These results provide the first backbone phylogeny and spatiotemporal reconstruction of the Aquilegia radiation, and constitute a robust framework to address the adaptative nature of speciation within the group.
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| 23. |
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| 24. |
- Frajman, B., et al.
(författare)
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Origin and Diversification of South American Polyploid Silene Sect. Physolychnis (Caryophyllaceae) in the Andes and Patagonia
- 2018
-
Ingår i: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- The Andes are an important biogeographic region in South America extending for about 8000 km from Venezuela to Argentina. They are - along with the Patagonian steppes - the main distribution area of ca. 18 polyploid species of Silene sect. Physolychnis. Using nuclear ITS and plastid psbE-petG and matK sequences, flow cytometric ploidy level estimations and chromosome counts, and including 13 South American species, we explored the origin and diversification of this group. Our data suggest a single, late Pliocene or early Pleistocene migration of the North American S. verecunda lineage to South America, which was followed by dispersal and diversification of this tetraploid lineage in the Andes, other Argentinian mountain ranges and the Patagonian steppes. Later in the Pleistocene South American populations hybridized with the S. uralensis lineage, which led to allopolyploidisation and origin of decaploid S. chilensis and S. echegarayi occurring at high elevations. Additionally, we show that the morphological differentiation in leaf shape correlated with divergent habitats (high elevation Andes vs. lower elevation Patagonian steppes) is also supported phylogenetically, especially in the ITS tree. Lastly, the species boundaries among the narrow-leaved Patagonian steppe species are poorly resolved and need more thorough taxonomic revision.
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| 25. |
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| 26. |
- Frajman, B., et al.
(författare)
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Reticulate phylogenetics and phytogeographical structure of Heliosperma (Sileneae, Caryophyllaceae) inferred from chloroplast and nuclear DNA sequences
- 2007
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 43:1, s. 140-155
-
Tidskriftsartikel (refereegranskat)abstract
- The Balkan Peninsula is known to be one of the most diverse and species-rich parts of Europe, but its biota has gained much less attention in phylogenetic and evolutionary studies compared to other southern European mountain systems. We used nuclear ribosomal internal transcribed spacer (ITS) sequences and intron sequences of the chloroplast gene rps16 to examine phylogenetic and biogeographical patterns within the genus Heliosperma (Sileneae, Caryophyllaceae). The ITS and rps16 intron sequences both support monophyly of Heliosperma, but the data are not conclusive with regard to its exact origin. Three strongly supported clades are found in both data sets, corresponding to Heliosperma alpestre, Heliosperma macranthum and the Heliosperma pusillum clade, including all other taxa. The interrelationships among these three differ between the nuclear and the plastid data sets. Hierarchical relationships within the H. pusillum clade are poorly resolved by the ITS data, but the rps16 intron sequences form two well-supported clades which are geographically, rather than taxonomically, correlated. A similar geographical structure is found in the ITS data, when analyzed with the NeighbourNet method. The apparent rate of change within Heliosperma is slightly higher for rps16 as compared to ITS. In contrast, in the Sileneae outgroup, ITS substitution rates are more than twice as high as those for rps16, a situation more in agreement with what has been found in other rate comparisons of noncoding cpDNA and ITS. Unlike most other Sileneae ITS sequences, the H. pusillum group sequences display extensive polymorphism. A possible explanation to these patterns is extensive hybridization and gene flow within Heliosperma, which together with concerted evolution may have eradicated the ancient divergence suggested by the rps16 data. The morphological differentiation into high elevation, mainly widely distributed taxa, and low elevation narrow endemics is not correlated with the molecular data, and is possibly a result of ecological differentiation. (c) 2006 Elsevier Inc. All rights reserved.
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| 27. |
- Frajman, B., et al.
(författare)
-
Taxonomic revision of Atocion and Viscaria (Sileneae, Caryophyllaceae)
- 2013
-
Ingår i: Botanical Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4074 .- 1095-8339. ; 173:2, s. 194-210
-
Tidskriftsartikel (refereegranskat)abstract
- A species-level taxonomic revision of Atocion and Viscaria, based on a recent phylogenetic study, is presented. Atocion includes six species (A. armeria, A. compactum, A. lerchenfeldianum, A. reuterianum, A. rupestre and A. scythicinum), and Viscaria includes three species (V. alpina, V. asterias and V. vulgaris). The highest species diversity is found on the Balkan Peninsula. Species descriptions based on a study of morphological characters and generated using the Prometheus description model are provided and are also available in the Sileneae online database. Complete synonymy, notes on the ecology and geographical distribution of the taxa and an identification key are provided. Lectotypes for nine names (Lychnis helvetica, L. suecica, Silene armeria var. angustifolia, S. berdaui, S. lituanica, S. compacta, S. orientalis, S. reuteriana and Viscaria media) and a neotype for one name (S. lerchenfeldiana) are assigned. (C) 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173, 194-210.
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| 28. |
- Gibson, A. K., et al.
(författare)
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Life-history strategy defends against disease and may select against physiological resistance
- 2013
-
Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 3:6, s. 1741-1750
-
Tidskriftsartikel (refereegranskat)abstract
- Host ecological traits may limit exposure to infectious disease, thereby generating the wide variation in disease incidence observed between host populations or species. The exclusion of disease by ecological traits may then allow selection to act against physiological defenses when they are costly to maintain in the absence of disease. This study investigates ecological resistance in the Silene-Microbotryum pathosystem. An estimated 80% of perennial Silene species host the anther-smut disease while no annuals harbor the disease in nature. Artificial inoculations of annual and perennial Silene plants, obtained from both natural and horticultural populations, demonstrate that the absence of disease in annuals is not explained by elevated physiological resistance. The annual habit is thus a powerful form of ecological defense against anther smut. Moreover, the higher susceptibility of annual species to anther smut relative to perennials supports the hypothesis of a loss of costly physiological resistance under ecological protection. The observation in annuals that physiological susceptibility is correlated with lower rates of flowering (i.e., lower fitness) suggests that variation in physiological resistance is costly in the absence of disease, even in a naїve Silene species. The absence of disease in natural populations of annuals combined with their high physiological susceptibility attest to the strength of host ecology in shaping the distribution of disease and to the dynamic nature of disease resistance.
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| 29. |
- Gizaw, A., et al.
(författare)
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Colonization and diversification in the African 'sky islands': insights from fossil-calibrated molecular dating of Lychnis (Caryophyllaceae)
- 2016
-
Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 211:2, s. 719-734
-
Tidskriftsartikel (refereegranskat)abstract
- The flora on the isolated high African mountains or 'sky islands' is remarkable for its peculiar adaptations, local endemism and striking biogeographical connections to remote parts of the world. Ages of the plant lineages and the timing of their radiations have frequently been debated but remain contentious as there are few estimates based on explicit models and fossil-calibrated molecular clocks. We used the plastid region maturaseK (matK) and a Caryophylloflora paleogenica fossil to infer the age of the genus Lychnis, and constructed a data set of three plastid (matK; a ribosomal protein S16 (rps16); and an intergenic spacer (psbE-petL)) and two nuclear (internal transcribed spacer (ITS) and a region spanning exon 18-24 in the second largest subunit of RNA polymerase II (RPB2)) loci for joint estimation of the species tree and divergence time of the African representatives. The time of divergence of the African high-altitude Lychnis was placed in the late Miocene to early Pliocene. A single speciation event was inferred in the early Pliocene; subsequent speciation took place sporadically from the late Pliocene to the middle Pleistocene. We provide further support for a Eurasian origin of the African 'sky islands' floral elements, which seem to have been recruited via dispersals at different times: some old, as in Lychnis, and others very recent. We show that dispersal and diversification within Africa play an important role in shaping these isolated plant communities.
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| 30. |
- Hood, Michael E, et al.
(författare)
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Distribution of the anther-smut pathogen Microbotryum on species of the Caryophyllaceae.
- 2010
-
Ingår i: The New phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 187:1, s. 217-29
-
Tidskriftsartikel (refereegranskat)abstract
- *Understanding disease distributions is of fundamental and applied importance, yet few studies benefit from integrating broad sampling with ecological and phylogenetic data. Here, anther-smut disease, caused by the fungus Microbotryum, was assessed using herbarium specimens of Silene and allied genera of the Caryophyllaceae. *A total of 42,000 herbarium specimens were examined, and plant geographical distributions and morphological and life history characteristics were tested as correlates of disease occurrence. Phylogenetic comparative methods were used to determine the association between disease and plant life-span. *Disease was found on 391 herbarium specimens from 114 species and all continents with native Silene. Anther smut occurred exclusively on perennial plants, consistent with the pathogen requiring living hosts to overwinter. The disease was estimated to occur in 80% of perennial species of Silene and allied genera. The correlation between plant life-span and disease was highly significant while controlling for the plant phylogeny, but the disease was not correlated with differences in floral morphology. *Using resources available in natural history collections, this study illustrates how disease distribution can be determined, not by restriction to a clade of susceptible hosts or to a limited geographical region, but by association with host life-span, a trait that has undergone frequent evolutionary transitions.
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| 31. |
- Hyde, Kevin D., et al.
(författare)
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Incorporating molecular data in fungal systematics: a guide for aspiring researchers
- 2013
-
Ingår i: Current Research in Environmental and Applied Mycology. - : Mushroom Research Foundation. - 2229-2225. ; 3:1
-
Tidskriftsartikel (refereegranskat)abstract
- The last twenty years have witnessed molecular data emerge as a primary research instrument in most branches of mycology. Fungal systematics, taxonomy, and ecology have all seen tremendous progress and have undergone rapid, far-reaching changes as disciplines in the wake of continual improvement in DNA sequencing technology. A taxonomic study that draws from molecular data involves a long series of steps, ranging from taxon sampling through the various laboratory procedures and data analysis to the publication process. All steps are important and influence the results and the way they are perceived by the scientific community. The present paper provides a reflective overview of all major steps in such a project with the purpose to assist research students about to begin their first study using DNA-based methods. We also take the opportunity to discuss the role of taxonomy in biology and the life sciences in general in the light of molecular data. While the best way to learn molecular methods is to work side by side with someone experienced, we hope that the present paper will serve to lower the learning threshold for the reader.
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| 32. |
- Ito, Yu, et al.
(författare)
-
Molecular phylogeny of the cosmopolitan aquatic plant genus Limosella (Scrophulariaceae) with a particular focus on the origin of the Australasian L. curdieana.
- 2017
-
Ingår i: Journal of plant research. - : Springer Science and Business Media LLC. - 1618-0860 .- 0918-9440. ; 130:1, s. 107-116
-
Tidskriftsartikel (refereegranskat)abstract
- Limosella is a small aquatic genus of Scrophulariaceae of twelve species, of which one is distributed in northern circumpolar regions, two in southern circumpolar regions, two in the Americas, one endemic to Australia, and six in tropical or southern Africa or both. The Australasian L. curdieana has always been considered distinct but its close phylogenetic relationships have never been inferred. Here, we investigated the following alternative phylogenetic hypotheses based on comparative leaf morphology and habitat preferences or floral morphology: (1) L. curdieana is sister to the African L. grandiflora; or (2) it is closely related to a group of other African species and the northern circumpolar L. aquatica. We tested these hypotheses in a phylogenetic framework using DNA sequence data from four plastid DNA regions and the nuclear ITS region. These were analyzed using maximum parsimony and Bayesian inference. We obtained moderately resolved, partially conflicting phylogenies, supporting that accessions of L. grandiflora form the sister group to the rest of the genus and that L. curdieana groups with the African taxa, L. africana and L. major, and L. aquatica. Thus, the molecular evidence supports the second hypothesis. A biogeographic analysis suggests an out-of-southern Africa scenario and several dispersal events in the Southern Hemisphere. Past dispersal from southern Africa to Australasia is suggested, yet it cannot be excluded that a route via tropical Africa and temperate Asia has existed.
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| 33. |
- Jafari, Farzaneh, et al.
(författare)
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A new taxonomic backbone for the infrageneric classification of the species-rich genus Silene(Caryophyllaceae)
- 2020
-
Ingår i: Taxon. - : Wiley. - 0040-0262 .- 1996-8175. ; 69:2, s. 337-368
-
Tidskriftsartikel (refereegranskat)abstract
- The systematization of species in plant taxonomy based on the phylogenetic relationships among them are of utmost importance and also very challenging in large genera. In those, phylogenetic results often may suggest substantially different relationships than previous classifications, and call for large-scale taxonomic revisions. Delimitation of the genusSilenehas been and is still somewhat controversial, and recent molecular phylogenetic studies have settled several monophyletic groups that differ substantially from previous taxonomies. The infrageneric taxonomy ofSilenes.str. has not been updated as a whole taking the phylogenetic information into account. In this study, we review previous phylogenetic results based on multiple loci, and conducted comprehensive gene tree analyses based on the nrDNA ITS and cpDNArps16regions for 1586 and 944 samples representing 415 and 397 species, respectively, includingSileneand its allies, as well as a species tree analysis including 262 samples representing 243 species. We sampled representatives from all 44 sections recognized in the most recent global revision of the genus. The results support the recognition of three subgenera, i.e.,S.subg.Behenantha,S.subg.LychnisandS. subg.Silene, which is partly in agreement with previous molecular phylogenetic findings and contradicts all previous traditional classifications.Silenesect.Atocion, with a few annual species showing a narrow distribution range in the eastern Mediterranean, is treated as incertae sedis because of its uncertain phylogenetic position, possibly due to exceptionally high substitution rates.Silenesubg.Lychnis, weakly supported as sister to the other subgenera, splits into three main clades and includes four sections.Silenesubg.Behenantha, which forms a possible sister group in relation toS.subg.Silene, is poorly resolved basally and includes a large number of mostly small clades recognized as 18 sections. InS.subg.Silene, 11 sections are recognized, among which four are broadly circumscribed:S.sect.Auriculatae,S.sect.Sclerocalycinae,S.sect.SileneandS.sect.Siphonomorpha.Silenesect.AcutifoliaeandS.sect.Portensesare described here as new taxa, whereas new status or new combinations are proposed forS.sect.Anotites,S.sect.Muscipula,S.sect.Petrocoma,S.sect.Pulvinatae,S.sect.SclerophyllaeandS.sect.Uebelinia. Five new combinations and two new names are proposed for taxa inSileneformerly assigned toLychnisandUebelinia. The correct infrageneric nomenclature compatible with the new infrageneric system is provided along with synonymy and type citations. Shortcomings of this study, such as the lack of a morphological diagnostic key and sparse sampling of some large sections, are listed and discussed.
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| 34. |
- Jafari, F., et al.
(författare)
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Notes on the genus Silene (Caryophyllaceae, Sileneae) in Iran
- 2019
-
Ingår i: Phytotaxa. - : Magnolia Press. - 1179-3155 .- 1179-3163. ; 425:1, s. 35-48
-
Tidskriftsartikel (refereegranskat)abstract
- Two new species-Silene orientoalborzensis and S. circumcarmanica-are here described from Northeast and South Iran, respectively. They belong to Silene subg. Silene sect. Auriculatae which is the largest section of the genus in W-Asia. A specimen from center of Iran, which was identified erroneously as S. atocioides, is revised and identified as S. pendula which represents a new record for the Iranian flora. S. simsii is proposed as a nomen novum for Cucubalus multifidus.
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| 35. |
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| 36. |
- Jones, Graham, et al.
(författare)
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DISSECT: an assignment-free Bayesian discovery method for species delimitation under the multispecies coalescent
- 2015
-
Ingår i: Bioinformatics. - : Oxford University Press (OUP). - 1367-4803 .- 1367-4811. ; 31:7, s. 991-998
-
Tidskriftsartikel (refereegranskat)abstract
- Motivation: The multispecies coalescent model provides a formal framework for the assignment of individual organisms to species, where the species are modeled as the branches of the species tree. None of the available approaches so far have simultaneously co-estimated all the relevant parameters in the model, without restricting the parameter space by requiring a guide tree and/or prior assignment of individuals to clusters or species. Results: We present DISSECT, which explores the full space of possible clusterings of individuals and species tree topologies in a Bayesian framework. It uses an approximation to avoid the need for reversible-jump MCMC, in the form of a prior that is a modification of the birth-death prior for the species tree. It incorporates a spike near zero in the density for node heights. The model has two extra parameters: one controls the degree of approximation, and the second controls the prior distribution on the numbers of species. It is implemented as part of BEAST and requires only a few changes from a standard *BEAST analysis. The method is evaluated on simulated data and demonstrated on an empirical data set. The method is shown to be insensitive to the degree of approximation, but quite sensitive to the second parameter, suggesting that large numbers of sequences are needed to draw firm conclusions.
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| 37. |
- Jones, Robert Graham, 1959, et al.
(författare)
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Statistical Inference of Allopolyploid Species Networks in the Presence of Incomplete Lineage Sorting.
- 2013
-
Ingår i: Systematic Biology. - : Oxford University Press (OUP). - 1063-5157 .- 1076-836X. ; 62:3, s. 467-478
-
Tidskriftsartikel (refereegranskat)abstract
- Polyploidy is an important speciation mechanism, particularly in land plants. Allopolyploid species are formed after hybridization between otherwise intersterile parental species. Recent theoretical progress has led to successful implementation of species tree models that take population genetic parameters into account. However, these models have not included allopolyploid hybridization and the special problems imposed when species trees of allopolyploids are inferred. Here, two new models for the statistical inference of the evolutionary history of allopolyploids are evaluated using simulations and demonstrated on two empirical data sets. It is assumed that there has been a single hybridization event between two diploid species resulting in a genomic allotetraploid. The evolutionary history can be represented as a species network or as a multi-labeled species tree, in which some pairs of tips are labeled with the same species. In one of the models (AlloppMUL), the multi-labeled species tree is inferred directly. This is the simplest model and the most widely applicable, since fewer assumptions are made. The second model (AlloppNET) incorporates the hybridization event explicitly which means that fewer parameters need to be estimated. Both models are implemented in the BEAST framework. Simulations show that both models are useful and that AlloppNET is more accurate if the assumptions it is based on are valid. The models are demonstrated on previously analyzed data from the genus Pachycladon (Brassicaceae) and from the genus Silene (Caryophyllaceae).
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| 38. |
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| 39. |
- Lott, Martin, et al.
(författare)
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Inferring polyploid phylogenies from multiply-labeled gene trees.
- 2009
-
Ingår i: BMC evolutionary biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Gene trees that arise in the context of reconstructing the evolutionary history of polyploid species are often multiply-labeled, that is, the same leaf label can occur several times in a single tree. This property considerably complicates the task of forming a consensus of a collection of such trees compared to usual phylogenetic trees. RESULTS: We present a method for computing a consensus tree of multiply-labeled trees. As with the well-known greedy consensus tree approach for phylogenetic trees, our method first breaks the given collection of gene trees into a set of clusters. It then aims to insert these clusters one at a time into a tree, starting with the clusters that are supported by most of the gene trees. As the problem to decide whether a cluster can be inserted into a multiply-labeled tree is computationally hard, we have developed a heuristic method for solving this problem. CONCLUSION: We illustrate the applicability of our method using two collections of trees for plants of the genus Silene, that involve several allopolyploids at different levels.
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| 40. |
- Madhani, H., et al.
(författare)
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Untangling phylogenetic patterns and taxonomic confusion in tribe Caryophylleae (Caryophyllaceae) with special focus on generic boundaries
- 2018
-
Ingår i: Taxon. - : Wiley. - 0040-0262 .- 1996-8175. ; 67:1, s. 83-112
-
Tidskriftsartikel (refereegranskat)abstract
- Assigning correct names to taxa is a challenging goal in the taxonomy of many groups within the Caryophyllaceae. This challenge is most serious in tribe Caryophylleae since the supposed genera seem to be highly artificial, and the available morphological evidence cannot effectively be used for delimitation and exact determination of taxa. The main goal of the present study was to re-assess the monophyly of the genera currently recognized in this tribe using molecular phylogenetic data. We used the sequences of nuclear ribosomal internal transcribed spacer (ITS) and the chloroplast gene rps16 for 135 and 94 accessions, respectively, representing all 16 genera currently recognized in the tribe Caryophylleae, with a rich sampling of Gypsophila as one of the most heterogeneous groups in the tribe. Phylogenetic trees were reconstructed using maximum parsimony and Bayesian inference methods. The results show that most of the large genera of Caryophylleae are not monophyletic. As a result, we propose a new classification system matching both molecular phylogenetic and morphological evidence. The main taxonomic conclusions include: (1) the description of three new genera, (2) treating five small genera as synonyms, (3) resurrecting the genus Heterochroa with six species, and (4) proposing 23 new combinations plus 2 replacement names at the specific level. As a result, we recognize 14 genera in Caryophylleae. A diagnostic key to all genera of Caryophylleae is provided.
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| 41. |
- Marcussen, Thomas, et al.
(författare)
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Evolution of plant RNA polymerase IV/V genes: evidence of subneofunctionalization of duplicated NRPD2/NRPE2-like paralogs in Viola (Violaceae).
- 2010
-
Ingår i: BMC evolutionary biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: BACKGROUND: DNA-dependent RNA polymerase IV and V (Pol IV and V) are multi-subunit enzymes occurring in plants. The origin of Pol V, specific to angiosperms, from Pol IV, which is present in all land plants, is linked to the duplication of the gene encoding the largest subunit and the subsequent subneofunctionalization of the two paralogs (NRPD1 and NRPE1). Additional duplication of the second-largest subunit, NRPD2/NRPE2, has happened independently in at least some eudicot lineages, but its paralogs are often subject to concerted evolution and gene death and little is known about their evolution nor their affinity with Pol IV and Pol V. RESULTS: We sequenced a ~1500 bp NRPD2/E2-like fragment from 18 Viola species, mostly paleopolyploids, and 6 non-Viola Violaceae species. Incongruence between the NRPD2/E2-like gene phylogeny and species phylogeny indicates a first duplication of NRPD2 relatively basally in Violaceae, with subsequent sorting of paralogs in the descendants, followed by a second duplication in the common ancestor of Viola and Allexis. In Viola, the mutation pattern suggested (sub-) neofunctionalization of the two NRPD2/E2-like paralogs, NRPD2/E2-a and NRPD2/E2-b. The dN/dS ratios indicated that a 54 bp region exerted strong positive selection for both paralogs immediately following duplication. This 54 bp region encodes a domain that is involved in the binding of the Nrpd2 subunit with other Pol IV/V subunits, and may be important for correct recognition of subunits specific to Pol IV and Pol V. Across all Viola taxa 73 NRPD2/E2-like sequences were obtained, of which 23 (32%) were putative pseudogenes - all occurring in polyploids. The NRPD2 duplication was conserved in all lineages except the diploid MELVIO clade, in which NRPD2/E2-b was lost, and its allopolyploid derivates from hybridization with the CHAM clade, section Viola and section Melanium, in which NRPD2/E2-a occurred in multiple copies while NRPD2/E2-b paralogs were either absent or pseudogenized. CONCLUSIONS: Following the relatively recent split of Pol IV and Pol V, our data indicate that these two multi-subunit enzymes are still in the process of specialization and each acquiring fully subfunctionalized copies of their subunit genes. Even after specialization, the NRPD2/E2-like paralogs are prone to pseudogenization and gene conversion and NRPD2 and NRPE2 copy number is a highly dynamic process modulated by allopolyploidy and gene death.
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| 42. |
- Marcussen, Thomas, 1971, et al.
(författare)
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From Gene Trees to a Dated Allopolyploid Network: Insights from the Angiosperm Genus Viola (Violaceae)
- 2015
-
Ingår i: Systematic Biology. - : Oxford University Press (OUP). - 1063-5157 .- 1076-836X. ; 64:1, s. 84-101
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Tidskriftsartikel (refereegranskat)abstract
- Allopolyploidization accounts for a significant fraction of speciation events in many eukaryotic lineages. However, existing phylogenetic and dating methods require tree-like topologies and are unable to handle the network-like phylogenetic relationships of lineages containing allopolyploids. No explicit framework has so far been established for evaluating competing network topologies, and few attempts have been made to date phylogenetic networks. We used a four-step approach to generate a dated polyploid species network for the cosmopolitan angiosperm genus Viola L. (Violaceae Batch.). The genus contains ca 600 species and both recent (neo-) and more ancient (meso-) polyploid lineages distributed over 16 sections. First, we obtained DNA sequences of three low-copy nuclear genes and one chloroplast region, from 42 species representing all 16 sections. Second, we obtained fossil-calibrated chronograms for each nuclear gene marker. Third, we determined the most parsimonious multilabeled genome tree and its corresponding network, resolved at the section (not the species) level. Reconstructing the “correct” network for a set of polyploids depends on recovering all homoeologs, i.e., all subgenomes, in these polyploids. Assuming the presence of Viola subgenome lineages that were not detected by the nuclear gene phylogenies (“ghost subgenome lineages”) significantly reduced the number of inferred polyploidization events. We identified the most parsimonious network topology from a set of five competing scenarios differing in the interpretation of homoeolog extinctions and lineage sorting, based on (i) fewest possible ghost subgenome lineages, (ii) fewest possible polyploidization events, and (iii) least possible deviation from expected ploidy as inferred from available chromosome counts of the involved polyploid taxa. Finally, we estimated the homoploid and polyploid speciation times of the most parsimonious network. Homoploid speciation times were estimated by coalescent analysis of gene tree node ages. Polyploid speciation times were estimated by comparing branch lengths and speciation rates of lineages with and without ploidy shifts. Our analyses recognize Viola as an old genus (crown age 31Ma) whose evolutionary history has been profoundly affected by allopolyploidy. Between 16 and 21 allopolyploidizations are necessary to explain the diversification of the 16 major lineages (sections) of Viola, suggesting that allopolyploidy has accounted for a high percentage—between 67% and 88%—of the speciation events at this level. The theoretical and methodological approaches presented here for (i) constructing networks and (ii) dating speciation events within a network, have general applicability for phylogenetic studies of groups where allopolyploidization has occurred. They make explicit use of a hitherto underexplored source of ploidy information from chromosome counts to help resolve phylogenetic cases where incomplete sequence data hampers network inference. Importantly, the coalescent-based method used herein circumvents the assumption of tree-like evolution required by most techniques for dating speciation events.
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| 43. |
- Marcussen, Thomas, 1971, et al.
(författare)
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Inferring species networks from gene trees in high-polyploid North American and Hawaiian violets (Viola, Violaceae).
- 2012
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Ingår i: Systematic biology. - : Oxford University Press (OUP). - 1076-836X .- 1063-5157. ; 61:1, s. 107-26
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Tidskriftsartikel (refereegranskat)abstract
- The phylogenies of allopolyploids take the shape of networks and cannot be adequately represented as bifurcating trees. Especially for high polyploids (i.e., organisms with more than six sets of nuclear chromosomes), the signatures of gene homoeolog loss, deep coalescence, and polyploidy may become confounded, with the result that gene trees may be congruent with more than one species network. Herein, we obtained the most parsimonious species network by objective comparison of competing scenarios involving polyploidization and homoeolog loss in a high-polyploid lineage of violets (Viola, Violaceae) mostly or entirely restricted to North America, Central America, or Hawaii. We amplified homoeologs of the low-copy nuclear gene, glucose-6-phosphate isomerase (GPI), by single-molecule polymerase chain reaction (PCR) and the chloroplast trnL-F region by conventional PCR for 51 species and subspecies. Topological incongruence among GPI homoeolog subclades, owing to deep coalescence and two instances of putative loss (or lack of detection) of homoeologs, were reconciled by applying the maximum tree topology for each subclade. The most parsimonious species network and the fossil-based calibration of the homoeolog tree favored monophyly of the high polyploids, which has resulted from allodecaploidization 9-14 Ma, involving sympatric ancestors from the extant Viola sections Chamaemelanium (diploid), Plagiostigma (paleotetraploid), and Viola (paleotetraploid). Although two of the high-polyploid lineages (Boreali-Americanae, Pedatae) remained decaploid, recurrent polyploidization with tetraploids of section Plagiostigma within the last 5 Ma has resulted in two 14-ploid lineages (Mexicanae, Nosphinium) and one 18-ploid lineage (Langsdorffianae). This implies a more complex phylogenetic and biogeographic origin of the Hawaiian violets (Nosphinium) than that previously inferred from rDNA data and illustrates the necessity of considering polyploidy in phylogenetic and biogeographic reconstruction.
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| 44. |
- Moazzeni, Hamid, et al.
(författare)
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Phylogenetic perspectives on diversification, biogeography and character evolution in the species-rich genus Erysimum (Erysimeae; Brassicaceae) based on a densely sampled ITS approach
- 2014
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Ingår i: Botanical journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4074 .- 1095-8339. ; 175:4, s. 497-522
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Tidskriftsartikel (refereegranskat)abstract
- Erysimum includes 150–350 species distributed in the Northern Hemisphere, with Eurasia being the centre of greatest diversity. It is well known for its taxonomic complexity as a result of overlapping morphological characters. We present the first densely sampled phylogenetic analysis of Erysimum using internal transcribed spacer (ITS) DNA sequences from c. 85% of the species (117 for the first time), representing the full range of morphological variation and geographical distribution. We used several approaches to reconstruct phylogenetic relationships, dating of diversification and patterns of evolution of morphological characters in the genus. Ancestral-state reconstructions of four morphological diagnostic characters were performed using maximum parsimony, maximum likelihood and Bayesian methods. Our phylogenetic framework strongly supports the monophyly of Erysimum and recovers some well-supported clades that are geographically, rather than morphologically, correlated. Our study confirms the placement of Erysimum in lineage I and reveals two Malcolmia spp. (M.maritima and M.orsiniana) as its sister taxa. The results suggest that the biennial duration and caespitose habit (vs. annual or perennial duration and herbaceous or woody habit) and large, yellow, glabrous (vs. small, non-yellow, pubescent) petals are ancestral in Erysimum. The ancestral-state reconstruction results show that annual vs. perennial and woody vs. herbaceous features have been independently derived several times. The dating analyses suggest an early radiation of Erysimum during the late Pliocene or early Pleistocene.
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| 45. |
- Moiloa, Ntwai A., et al.
(författare)
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Biogeographic origins of southern African Silene (Caryophyllaceae)
- 2021
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903. ; 162
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Tidskriftsartikel (refereegranskat)abstract
- Silene (Caryophyllaceae) is distributed predominantly in the northern Hemisphere, where it is most diverse around the Mediterranean Basin. The genus is also well represented in North Africa, extending into tropical, subSaharan and southern Africa. Eight native species are recognized in southern Africa, taxonomically placed in two sections: Elisanthe and Silene s.l. Although the taxonomy of the southern African taxa has recently been revised, their phylogenetic relationships and biogeographic history remain unclear. This study aims to infer the phylogenetic position and geographic origins of the southern African taxa. We generated DNA sequences of nuclear and plastid loci from several individuals belonging to all eight species of Silene recognized from southern Africa, and combined our DNA sequences with existing data representing species from major clades (i.e. sections) based on the recently revised Silene infrageneric taxonomy. We used a Bayesian coalescent species tree continuous diffusion approach to co-estimate the species tree and the ancestral areas of representative members of the genus. Our results show that the perennial southern African members of section Elisanthe form a strongly-supported clade with the Eurasian annual S. noctiflora and the Central Asian perennial S. turkestanica. The rest of the perennial species form a strongly-supported clade together with the annual S. aethiopica, which is nested in a larger Mediterranean clade comprising mostly annual species classified in section Silene s.l. Estimates of ancestral areas indicate a late Pleistocene dispersal to southern Africa from central and East Africa for the sub-Saharan members of section Silene s.l. The Elisanthe clade is inferred to have colonized southern Africa through longdistance dispersal from Eurasia during the late Pleistocene. Our findings support the hypothesis of a relatively recent colonization into southern Africa resulting from two independent dispersal events during the Pleistocene.
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| 46. |
- Moiloa, Ntwai A., et al.
(författare)
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Chapter 19 Systematics and evolution
- 2022
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Ingår i: In: de Boer H, Rydmark MO, Verstraete B, Gravendeel B (2022) Molecular identification of plants: from sequence to species. Advanced Books.. - : Pensoft Publishers.
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Bokkapitel (refereegranskat)
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| 47. |
- Naciri, Yamama, et al.
(författare)
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A phylogenetic circumscription of Silene sect. Siphonomorpha (Caryophyllaceae) in the Mediterranean basin
- 2017
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Ingår i: Taxon. - : Wiley. - 0040-0262 .- 1996-8175. ; 66:1, s. 91-108
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Tidskriftsartikel (refereegranskat)abstract
- © International Association for Plant Taxonomy (IAPT) 2017. Silene sect. Siphonomorpha (Caryophyllaceae) has historically either been split into three different and homogeneous entities (sect. Italicae, sect. Paradoxae, sect. Siphonomorpha s.str.) or considered as a single group (sect. Siphonomorpha s.l.). In this study, we investigate the delimitation of sect. Siphonomorpha s.l. and the three subgroups, in order to sort out previous taxonomic concepts. We first performed an analysis of nuclear ribosomal internal transcribed spacer (ITS) sequences with wide taxonomic sampling to place sect. Siphonomorpha within the genus. Then, using nuclear and chloroplast sequences in a multi-species coalescent context, we constructed two species trees with independent specimen sampling. One was based on ITS, the nuclear RPA2 gene, and the plastid rps16 gene, the other used ITS and the plastid trnH-psbA and trnS-trnG regions. The results are congruent among the three analyses and show that sect. Siphonomorpha s.l. is not supported as being monophyletic and that an extended concept of this section would include species also belonging to sections Saxifragoideae, Coronatae, Tataricae, Chloranthae, Barbeyanae, Nanosilene, Otites, Koreanae, Brachypodae, Graminiformes, Dianthoidea, Longitubulosae and Holopetalae. However, the three entities “Italicae”, “Paradoxae” and “Siphonomorpha s.str.” are monophyletic with minor alterations and deserve taxonomic recognition as sections. Several ambiguous species are now resolved, among them the position of S. gigantea which is shown to be a highly supported clade, sister of sect. Italicae, that could therefore be named sect. Giganteae.
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| 48. |
- Nylinder, Stephan, 1975, et al.
(författare)
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A dated species-tree approach to the trans-Pacific disjunction of the genus Jovellana (Calceolariaceae, Lamiales)
- 2012
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Ingår i: Taxon. - 0040-0262. ; 61:2, s. 381-391
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Tidskriftsartikel (refereegranskat)abstract
- The genus Jovellana is the sister group to the larger genus Calceolaria, together composing the family Calceolariaceae. Four species are currently recognised, two in New Zealand J. sinclairii, J. repens) and two in Chile (J. punctata, J. violacea). The distribution is disjunct across the Pacific Ocean and has long been believed to be a remnant of an ancient vicariance following the break-up of Gondwana. In this study we infer a species-tree phylogeny of the genus using three chloroplast and four nuclear DNA sequences. By exploring three modes of estimating stem and crown ages of the family Calceolariaceae, a Jovellana species tree could be inferred and dated using a secondary calibration. With this approach we can demonstrate that genetic data, despite slightly different signals from unlinked and linked molecular markers, support the idea that the presence of Jovellana in New Zealand is the result of recent long-distance dispersal across the Pacific Ocean from South America.
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| 49. |
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| 50. |
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