scholarly journals Bayesian phylogenetic analysis for diploid and allotetraploid species networks

2017 ◽  
Author(s):  
Graham Jones

AbstractAllopolyploid species are formed by genome doubling after hybridization between otherwise intersterile parental species. Allopolyploidy is a common speciation mechanism in land plants. Here we describe and evaluate a Bayesian approach to the phylogenetic analysis of species relationships when both ordinary speciation and allopolyploidy are present. The approach takes incomplete lineage sorting into account using the multi-species coalescent model, and extends this to deal with the extra complications due to allopolyploidy. The number of hybridizations is not assumed, which means that the number of parameters varies and a reversible-jump MCMC algorithm is needed to sample from the posterior. The main restriction is that only diploids and allotetraploids are considered. The model is implemented in the BEAST framework and is an extension of Jones et al. (2013). Simulations show that the topology of the network can be reliably inferred along with estimates of other parameters.

Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 455
Author(s):  
Na Ra Jeong ◽  
Min Jee Kim ◽  
Sung-Soo Kim ◽  
Sei-Woong Choi ◽  
Iksoo Kim

Conogethes pinicolalis has long been considered as a Pinaceae-feeding type of the yellow peach moth, C. punctiferalis, in Korea. In this study, the divergence of C. pinicolalis from the fruit-feeding moth C. punctiferalis was analyzed in terms of morphology, ecology, and genetics. C. pinicolalis differs from C. punctiferalis in several morphological features. Through field observation, we confirmed that pine trees are the host plants for the first generation of C. pinicolalis larvae, in contrast to fruit-feeding C. punctiferalis larvae. We successfully reared C. pinicolalis larvae to adults by providing them pine needles as a diet. From a genetic perspective, the sequences of mitochondrial COI of these two species substantially diverged by an average of 5.46%; moreover, phylogenetic analysis clearly assigned each species to an independent clade. On the other hand, nuclear EF1α showed a lower sequence divergence (2.10%) than COI. Overall, EF1α-based phylogenetic analysis confirmed each species as an independent clade, but a few haplotypes of EF1α indicated incomplete lineage sorting between these two species. In conclusion, our results demonstrate that C. pinicolalis is an independent species according to general taxonomic criteria; however, analysis of the EF1α sequence revealed a short divergence time.


2018 ◽  
Author(s):  
Richard J. Wang ◽  
Matthew W. Hahn

AbstractSpeciation genes are responsible for reproductive isolation between species. By directly participating in the process of speciation, the genealogies of isolating loci have been thought to more faithfully represent species trees. The unique properties of speciation genes may provide valuable evolutionary insights and help determine the true history of species divergence. Here, we formally analyze whether genealogies from loci participating in Dobzhansky-Muller (DM) incompatibilities are more likely to be concordant with the species tree under incomplete lineage sorting (ILS). Individual loci differ stochastically from the true history of divergence with a predictable frequency due to ILS, and these expectations—combined with the DM model of intrinsic reproductive isolation from epistatic interactions—can be used to examine the probability of concordance at isolating loci. Contrary to existing verbal models, we find that reproductively isolating loci that follow the DM model are often more likely to have discordant gene trees. These results are dependent on the pattern of isolation observed between three species, the time between speciation events, and the time since the last speciation event. Results supporting a higher probability of discordance are found for both derived-derived and derived-ancestral DM pairs, and regardless of whether incompatibilities are allowed or prohibited from segregating in the same population. Our overall results suggest that DM loci are unlikely to be especially useful for reconstructing species relationships, even in the presence of gene flow between incipient species, and may in fact be positively misleading.


2018 ◽  
Vol 31 (1) ◽  
pp. 16 ◽  
Author(s):  
Rosemary A. Barrett ◽  
Michael J. Bayly ◽  
Marco F. Duretto ◽  
Paul I. Forster ◽  
Pauline Y. Ladiges ◽  
...  

This study presents a phylogeny of Zieria Sm. (Rutaceae) based on sequences of internal transcribed spacer and external transcribed spacer regions of nrDNA, and using Neobyrnesia suberosa J.A.Armstr. as the outgroup. The phylogeny includes 109 samples, representing 58 of the 60 currently recognised species of Zieria, with multiple accessions of most. Ten species were resolved as monophyletic on the basis of two, or in one case four, samples. Monophyly of four species was neither supported nor rejected, and all other species with more than one accession were resolved as polyphyletic or paraphyletic. Results showed that divergent paralogues of nrDNA are present in some individuals, although the underlying evolutionary process that gave rise to those paralogues is uncertain. Divergent paralogues within genomes could predate speciation and be variably retained or variably detected within the species sampled here; alternatively, they could represent novel nrDNA combinations formed through hybridisation after speciation. There was no strong evidence for recombination between paralogues or that paralogues represent pseudogenes. Variation of nrDNA sequences was clearly incongruent with previously published cpDNA variation, with the nrDNA potentially providing a better indication of species relationships in Zieria. Evidence for this comes from the greater level of congruence, in some species at least, between nrDNA and existing species-level taxonomy than between cpDNA and taxonomy. Incomplete lineage sorting is proposed as a plausible cause for much of the conflict between nrDNA and cpDNA in Zieria, although, in most cases, there was insufficient information to identify the underlying causes with confidence. Implications for species-level taxonomy are discussed.


2020 ◽  
Author(s):  
Liming Cai ◽  
Zhenxiang Xi ◽  
Emily Moriarty Lemmon ◽  
Alan R Lemmon ◽  
Austin Mast ◽  
...  

Abstract The genomic revolution offers renewed hope of resolving rapid radiations in the Tree of Life. The development of the multispecies coalescent (MSC) model and improved gene tree estimation methods can better accommodate gene tree heterogeneity caused by incomplete lineage sorting (ILS) and gene tree estimation error stemming from the short internal branches. However, the relative influence of these factors in species tree inference is not well understood. Using anchored hybrid enrichment, we generated a data set including 423 single-copy loci from 64 taxa representing 39 families to infer the species tree of the flowering plant order Malpighiales. This order includes nine of the top ten most unstable nodes in angiosperms, which have been hypothesized to arise from the rapid radiation during the Cretaceous. Here, we show that coalescent-based methods do not resolve the backbone of Malpighiales and concatenation methods yield inconsistent estimations, providing evidence that gene tree heterogeneity is high in this clade. Despite high levels of ILS and gene tree estimation error, our simulations demonstrate that these two factors alone are insufficient to explain the lack of resolution in this order. To explore this further, we examined triplet frequencies among empirical gene trees and discovered some of them deviated significantly from those attributed to ILS and estimation error, suggesting gene flow as an additional and previously unappreciated phenomenon promoting gene tree variation in Malpighiales. Finally, we applied a novel method to quantify the relative contribution of these three primary sources of gene tree heterogeneity and demonstrated that ILS, gene tree estimation error, and gene flow contributed to 10.0%, 34.8%, and 21.4% of the variation, respectively. Together, our results suggest that a perfect storm of factors likely influence this lack of resolution, and further indicate that recalcitrant phylogenetic relationships like the backbone of Malpighiales may be better represented as phylogenetic networks. Thus, reducing such groups solely to existing models that adhere strictly to bifurcating trees greatly oversimplifies reality, and obscures our ability to more clearly discern the process of evolution.


Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 28
Author(s):  
Umaru Bangura ◽  
Jacob Buanie ◽  
Joyce Lamin ◽  
Christopher Davis ◽  
Gédéon Ngiala Bongo ◽  
...  

Lassa fever is a viral hemorrhagic fever caused by the Lassa virus LASV, which was first isolated in the rodent Mastomys natalensis in 1974 in Kenema, Sierra Leone. As little is known about the abundance and the presence of LASV in rodents living in the Bo area, we carried out a small mammal longitudinal population survey. A standardized trapping session was performed in various habitats and seasons in six villages over two years (2014–2016) and samples collected were tested for arenavirus IgG and LASV. A Bayesian phylogenetic analysis was performed on sequences identified by PCR. A total of 1490 small mammals were collected, and 16 rodent species were identified, with M. natalensis (355, 24%) found to be the most prevalent species. Forty-one (2.8%) samples were IgG positive, and 31 of these were trapped in homes and 10 in surrounding vegetation. Twenty-nine of 41 seropositive rodents were M. natalensis. We detected four LASV by PCR in two villages, all found in M. natalensis. Phylogenetic analysis showed that the sequences were distributed within the Sierra Leonean clade within lineage IV, distinguishing a Bo sub-clade older than a Kenema sub-clade. Compared to other settings, we found a low abundance of M. natalensis and a low circulation of LASV in rodents in villages around Bo district.


Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 299
Author(s):  
Georgios Sioutas ◽  
Styliani Minoudi ◽  
Katerina Tiligada ◽  
Caterina Chliva ◽  
Alexandros Triantafyllidis ◽  
...  

Dermanyssus gallinae (the poultry red mite, PRM) is an important ectoparasite in the laying hen industry. PRM can also infest humans, causing gamasoidosis, which is manifested as skin lesions characterized by rash and itching. Recently, there has been an increase in the reported number of human infestation cases with D. gallinae, mostly associated with the proliferation of pigeons in cities where they build their nests. The human form of the disease has not been linked to swallows (Hirundinidae) before. In this report, we describe an incident of human gamasoidosis linked to a nest of swallows built on the window ledge of an apartment in the island of Kefalonia, Greece. Mites were identified as D. gallinae using morphological keys and amplifying the Cytochrome C oxidase subunit I (COI) gene by PCR. Bayesian phylogenetic analysis and median-joining network supported the identification of three PRM haplogroups and the haplotype isolated from swallows was identical to three PRM sequences isolated from hens in Portugal. The patient was treated with topical corticosteroids, while the house was sprayed with deltamethrin. After one week, the mites disappeared and clinical symptoms subsided. The current study is the first report of human gamasoidosis from PRM found in swallows’ nest.


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.


The Auk ◽  
2019 ◽  
Vol 136 (4) ◽  
Author(s):  
Catalina Palacios ◽  
Silvana García-R ◽  
Juan Luis Parra ◽  
Andrés M Cuervo ◽  
F Gary Stiles ◽  
...  

Abstract Ecological speciation can proceed despite genetic interchange when selection counteracts the homogenizing effects of migration. We tested predictions of this divergence-with-gene-flow model in Coeligena helianthea and C. bonapartei, 2 parapatric Andean hummingbirds with marked plumage divergence. We sequenced putatively neutral markers (mitochondrial DNA [mtDNA] and nuclear ultraconserved elements [UCEs]) to examine genetic structure and gene flow, and a candidate gene (MC1R) to assess its role underlying divergence in coloration. We also tested the prediction of Gloger’s rule that darker forms occur in more humid environments, and examined morphological variation to assess adaptive mechanisms potentially promoting divergence. Genetic differentiation between species was low in both ND2 and UCEs. Coalescent estimates of migration were consistent with divergence with gene flow, but we cannot reject incomplete lineage sorting reflecting recent speciation as an explanation for patterns of genetic variation. MC1R variation was unrelated to phenotypic differences. Species did not differ in macroclimatic niches but were distinct in morphology. Although we reject adaptation to variation in macroclimatic conditions as a cause of divergence, speciation may have occurred in the face of gene flow driven by other ecological pressures or by sexual selection. Marked phenotypic divergence with no neutral genetic differentiation is remarkable for Neotropical birds, and makes C. helianthea and C. bonapartei an appropriate system in which to search for the genetic basis of species differences employing genomics.


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