Nuclear and plastid DNA sequences reveal complex reticulate patterns in Australian water-lilies (Nymphaea subgenus Anecphya, Nymphaeaceae)

2008 ◽  
Vol 21 (4) ◽  
pp. 229 ◽  
Author(s):  
Cornelia Löhne ◽  
Thomas Borsch ◽  
Surrey W. L. Jacobs ◽  
C. Barre Hellquist ◽  
John H. Wiersema

This study represents the first comprehensive analysis of phylogenetic relationships within the Australian water-lilies, Nymphaea subg. Anecphya. Our 51-accession dataset covers all 10 species of the subgenus, except the newly described N. alexii, and includes information from the nuclear ITS as well as from the chloroplast trnT–trnF region. The results show that molecular data are consistent with morphology, because the subdivision of subg. Anecphya into two major clades, a large-seeded and a small-seeded group, could be confirmed. Within the large-seeded group, Nymphaea atrans and N. immutabilis seem to form one clade, whereas samples of N. gigantea, N. georginae, N. macrosperma and N. carpentariae form another. Relationships within the small-seeded group, containing all samples of N. violacea, N. elleniae and N. hastifolia, are less clear, since the trees obtained from the chloroplast and the nuclear marker are incongruent. The samples of N. violacea do not form a monophyletic group in each of the trees, but—at least in the ITS tree—group with either N. elleniae or N. hastifolia/Ondinea, respectively. Polymorphisms among ITS paralogues, i.e. substitutions at single nucleotide positions and length polymorphisms, have been observed in some samples of N. violacea. This fact as well as the incongruent phylogenetic signal obtained from the chloroplast and the nuclear genomes point to recent hybridisation or introgression in this group. Remarkably, Ondinea purpurea is resolved within the small-seeded group by both markers and seems to have a close relationship to N. hastifolia. Although incomplete lineage sorting cannot be fully excluded to explain high variability in N. violacea, molecular data potentially hint to a case of still imperfect taxonomy.

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

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


2021 ◽  
Vol 8 ◽  
Author(s):  
Francis J. Nge ◽  
Ed Biffin ◽  
Kevin R. Thiele ◽  
Michelle Waycott

Cytonuclear discordance, commonly detected in phylogenetic studies, is often attributed to hybridization and/or incomplete lineage sorting (ILS). New sequencing technologies and analytical approaches can provide new insights into the relative importance of these processes. Hybridization has previously been reported in the Australian endemic plant genus Adenanthos (Proteaceae). Like many Australian genera, Adenanthos is of relatively ancient origin, and provides an opportunity to examine long-term evolutionary consequences of gene flow between lineages. Using a hybrid capture approach, we assembled densely sampled low-copy nuclear and plastid DNA sequences for Adenanthos, inferred its evolutionary history, and used a Bayesian posterior predictive approach and coalescent simulations to assess relative contributions of hybridization and ILS to cytonuclear discordance. Our analyses indicate that strong incongruence detected between our plastid and nuclear phylogenies is not only the result of ILS, but also results from extensive ancient introgression as well as recent chloroplast capture and introgression between extant Adenanthos species. The deep reticulation was also detected from long-persisting chloroplast haplotypes shared between evolutionarily distant species. These haplotypes may have persisted for over 12 Ma in localized populations across southwest Western Australia, indicating that the region is not only an important area for old endemic lineages and accumulation of species, but is also characterized by persistence of high genetic diversity. Deep introgression in Adenanthos coincided with the rapid radiation of the genus during the Miocene, a time when many Australian temperate plant groups radiated in response to large-scale climatic change. This study suggests that ancient introgression may play an important role in the evolution of the Australian flora more broadly.


2020 ◽  
Author(s):  
Fernando Lopes ◽  
Larissa R Oliveira ◽  
Amanda Kessler ◽  
Yago Beux ◽  
Enrique Crespo ◽  
...  

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.


Phytotaxa ◽  
2021 ◽  
Vol 484 (3) ◽  
pp. 291-297
Author(s):  
XINYU XU ◽  
CHANG-CHUN DING ◽  
WENQI HU ◽  
XIA YU ◽  
YU ZHENG ◽  
...  

A new species of Cymbidium (Orchidaceae), Cymbidium xichouense, from Yunnan Province, China, is described and illustrated based on morphological evidence and molecular analyses. The new orchid is morphologically similar to C. qinbeiense, but it has several morphological features that distinguish it from C. qiubeinense and all other recognized species in Cymbidium. Phylogenetic analyses based on nuclear (ITS) and plastid DNA (matK) were conducted, and the results also supported the status of C. xichouense as a new species, which is sister to C. qiubeiense.


2001 ◽  
Vol 33 (3) ◽  
pp. 181-187 ◽  
Author(s):  
Christian Printzen ◽  
H. Thorsten Lumbsch ◽  
Alan Orange

AbstractBiatora Britannica sp. nov is described from Wales. The species is the sorediate sister taxon of the Madeiran Biatora hertelii. The close relationship is supported by the presence of the hymenial pigment Hertelii-green, which is hitherto known only from these two species. Molecular data from the nuclear ITS-region of 14 Bratora¯ species renders further support for the close relationship of both species. Sterile, sorediate material from the British Isles earlier referred to B. efflorescens may in fact belong to B. britannica.


2020 ◽  
Vol 63 (2) ◽  
pp. 121-137
Author(s):  
Katarzyna Anna Jadwiszczak ◽  
Lidia Vetchinnikova ◽  
Agnieszka Bona ◽  
Łukasz Tyburski ◽  
Tatiana Kuznetsova ◽  
...  

Trees and shrubs belonging to the Betula L. genus seem to represent one of the most confused interspecific relationships, and hybridization is considered to be one of the main factors responsible for the substantial genetic and morphological variation of birches. In the present investigation, the internal transcribed spacer ITS1 and ITS2 regions of nuclear ribosomal DNA, nuclear alcohol dehydrogenase (ADH) gene sequences and amplified fragment length polymorphisms (AFLPs) as well as the Atkinson discriminant function (ADF) of leaf morphology were used to verify hypotheses concerning the origin of the dark barked Betula obscura and B. pendula var. carelica with the patterned wood. Both plants were considered by different authors to be distinct species, intraspecific forms of common B. pendula or B. pubescens, or hybrid taxa between B. pendula and B. pubescens. In the phylogenetic trees, the ITS and ADH gene sequences of both B. obscura and B. pendula var. carelica clustered with those of B. pendula, whereas B. pubescens trees were somewhat distinct. In turn, the AFLPs revealed genetic similarity of B. pendula var. carelica to both frequent species, whereas B. obscura was clearly distinct from other birches. Values of the ADF indices of the rare birches were typical for B. pendula. In the light of the results obtained, we imply that B. obscura and B. pendula var. carelica represent an intraspecific variation of B. pendula, they are neither intraspecific taxa of B. pubescens nor hybrid species between the common birches. Different grouping of B. obscura in the AFLPs and DNA sequences analyses is likely a result of an unreliable phylogenetic signal of the former molecular markers.


2019 ◽  
Author(s):  
Mark S. Springer ◽  
John Gatesy

AbstractDNA sequence alignments provide the majority of data for inferring phylogenetic relationships with both concatenation and coalescence methods. However, DNA sequences are susceptible to extensive homoplasy, especially for deep divergences in the Tree of Life. Retroposon insertions have emerged as a powerful alternative to sequences for deciphering evolutionary relationships because these data are nearly homoplasy-free. In addition, retroposon insertions satisfy the ‘no intralocus recombination’ assumption of summary coalescence methods because they are singular events and better approximate neutrality relative to DNA sequences commonly applied in phylogenomic work. Retroposons have traditionally been analyzed with phylogenetic methods that ignore incomplete lineage sorting (ILS). Here, we analyze three retroposon data sets for mammals (Placentalia, Laurasiatheria, Balaenopteroidea) with two different ILS-aware methods. The first approach constructs a species tree from retroposon bipartitions with ASTRAL, and the second is a modification of SVD-Quartets. We also develop a χ2 Quartet-Asymmetry Test to detect hybridization using retroposon data. Both coalescence methods recovered the same topology for each of the three data sets. The ASTRAL species tree for Laurasiatheria has consecutive short branch lengths that are consistent with an anomaly zone situation. For the Balaenopteroidea data set, which includes rorquals (Balaenopteridae) and gray whale (Eschrichtiidae), both coalescence methods recovered a topology that supports the paraphyly of Balaenopteridae. Application of the χ2 Quartet-Asymmetry Test to this data set detected 16 different quartets of species for which historical hybridization may be inferred, but significant asymmetry was not detected in the placental root and Laurasiatheria analyses.


2021 ◽  
Author(s):  
Alexander Knyshov ◽  
Yana Hrytsenko ◽  
Robert Literman ◽  
Rachel S Schwartz

The position of some taxa on the Tree of Life remains controversial despite the increase in genomic data used to infer phylogenies. While analyzing large datasets alleviates stochastic errors, it does not prevent systematic errors in inference, caused by both biological (e.g., incomplete lineage sorting, hybridization) and methodological (e.g., incorrect modeling, erroneous orthology assessments) factors. In our study, we systematically investigated factors that could result in these controversies, using the treeshrew (Scandentia, Mammalia) as a study case. Recent studies have narrowed the phylogenetic position of treeshrews to three competing hypotheses: sister to primates and flying lemurs (Primatomorpha), sister to rodents and lagomorphs (Glires), or sister to a clade comprising all of these. We sampled 50 mammal species including three treeshrews, a selection of taxa from the potential sister groups, and outgroups. Using a large diverse set of loci, we assessed support for the alternative phylogenetic position of treeshrews. A plurality of loci support treeshrews as sister to rodents and lagomorphs; however, only a few loci exhibit strong support for any hypothesis. Surprisingly, we found that a subset of loci that strongly support the monophyly of Primates, support treeshrews as sister to primates and flying lemurs. The overall small magnitude of differences in phylogenetic signal among the alternative hypotheses suggests that these three groups diversified nearly simultaneously. However, with our large dataset and approach to examining support, we provide evidence for the hypothesis of treeshrews as sister to rodents and lagomorphs, while demonstrating why support for alternate hypotheses has been seen in prior work. We also suggest that locus selection can unwittingly bias results.


2011 ◽  
Vol 279 (1734) ◽  
pp. 1847-1856 ◽  
Author(s):  
Leonardo Campagna ◽  
Pilar Benites ◽  
Stephen C. Lougheed ◽  
Darío A. Lijtmaer ◽  
Adrián S. Di Giacomo ◽  
...  

Adaptive radiations have helped shape how we view animal speciation, particularly classic examples such as Darwin's finches, Hawaiian fruitflies and African Great Lakes cichlids. These ‘island’ radiations are comparatively recent, making them particularly interesting because the mechanisms that caused diversification are still in motion. Here, we identify a new case of a recent bird radiation within a continentally distributed species group; the capuchino seedeaters comprise 11 Sporophila species originally described on the basis of differences in plumage colour and pattern in adult males. We use molecular data together with analyses of male plumage and vocalizations to understand species limits of the group. We find marked phenotypic variation despite lack of mitochondrial DNA monophyly and few differences in other putatively neutral nuclear markers. This finding is consistent with the group having undergone a recent radiation beginning in the Pleistocene, leaving genetic signatures of incomplete lineage sorting, introgressive hybridization and demographic expansions. We argue that this apparent uncoupling between neutral DNA homogeneity and phenotypic diversity is expected for a recent group within the framework of coalescent theory. Finally, we discuss how the ecology of open habitats in South America during the Pleistocene could have helped promote this unique and ongoing radiation.


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