scholarly journals Natural hybridization among three Rhododendron species (Ericaceae) revealed by morphological and genomic evidence

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Zheng ◽  
Li-Jun Yan ◽  
Kevin S. Burgess ◽  
Ya-Huang Luo ◽  
Jia-Yun Zou ◽  
...  

Abstract Background Natural hybridization can influence the adaptive response to selection and accelerate species diversification. Understanding the composition and structure of hybrid zones may elucidate patterns of hybridization processes that are important to the formation and maintenance of species, especially for taxa that have experienced rapidly adaptive radiation. Here, we used morphological traits, ddRAD-seq and plastid DNA sequence data to investigate the structure of a Rhododendron hybrid zone and uncover the hybridization patterns among three sympatric and closely related species. Results Our results show that the hybrid zone is complex, where bi-directional hybridization takes place among the three sympatric parental species: R. spinuliferum, R. scabrifolium, and R. spiciferum. Hybrids between R. spinuliferum and R. spiciferum (R. ×duclouxii) comprise multiple hybrid classes and a high proportion of F1 generation hybrids, while a novel hybrid taxon between R. spinuliferum and R. scabrifolium dominated the F2 generation, but no backcross individuals were detected. The hybrid zone showed basically coincident patterns of population structure between genomic and morphological data. Conclusions Natural hybridization exists among the three Rhododendron species in the hybrid zone, although patterns of hybrid formation vary between hybrid taxa, which may result in different evolutionary outcomes. This study represents a unique opportunity to dissect the ecological and evolutionary mechanisms associated with adaptive radiation of Rhododendron species in a biodiversity hotspot.

2019 ◽  
Vol 110 (5) ◽  
pp. 523-534 ◽  
Author(s):  
Brendan J Pinto ◽  
James Titus-McQuillan ◽  
Juan D Daza ◽  
Tony Gamble

Abstract Determining the mechanisms that create and maintain biodiversity is a central question in ecology and evolution. Speciation is the process that creates biodiversity. Speciation is mediated by incompatibilities that lead to reproductive isolation between divergent populations and these incompatibilities can be observed in hybrid zones. Gecko lizards are a speciose clade possessing an impressive diversity of behavioral and morphological traits. In geckos, however, our understanding of the speciation process is negligible. To address this gap, we used genetic sequence data (both mitochondrial and nuclear markers) to revisit a putative hybrid zone between Sphaerodactylus nicholsi and Sphaerodactylus townsendi in Puerto Rico, initially described in 1984. First, we addressed discrepancies in the literature on the validity of both species. Second, we sampled a 10-km-wide transect across the putative hybrid zone and tested explicit predictions about its dynamics using cline models. Third, we investigated potential causes for the hybrid zone using species distribution modeling and simulations; namely, whether unique climatic variables within the hybrid zone might elicit selection for intermediate phenotypes. We find strong support for the species-level status of each species and no evidence of movement, or unique climatic variables near the hybrid zone. We suggest that this narrow hybrid zone is geographically stable and is maintained by a combination of dispersal and selection. Thus, this work has identified an extant model system within geckos that that can be used for future investigations detailing genetic mechanisms of reproductive isolation in an understudied vertebrate group.


2013 ◽  
Vol 300 (4) ◽  
pp. 645-664 ◽  
Author(s):  
Mubo A. Sonibare ◽  
Metin Armagan ◽  
Fevzi Özgökce ◽  
Ahmet Emre Yaprak ◽  
Eike Mayland-Quellhorst ◽  
...  

Author(s):  
Sara Fuentes-Soriano ◽  
Elizabeth A. Kellogg

Physarieae is a small tribe of herbaceous annual and woody perennial mustards that are mostly endemic to North America, with its members including a large amount of variation in floral, fruit, and chromosomal variation. Building on a previous study of Physarieae based on morphology and ndhF plastid DNA, we reconstructed the evolutionary history of the tribe using new sequence data from two nuclear markers, and compared the new topologies against previously published cpDNA-based phylogenetic hypotheses. The novel analyses included ca. 420 new sequences of ITS and LUMINIDEPENDENS (LD) markers for 39 and 47 species, respectively, with sampling accounting for all seven genera of Physarieae, including nomenclatural type species, and 11 outgroup taxa. Maximum parsimony, maximum likelihood, and Bayesian analyses showed that these additional markers were largely consistent with the previous ndhF data that supported the monophyly of Physarieae and resolved two major clades within the tribe, i.e., DDNLS (Dithyrea, Dimorphocarpa, Nerisyrenia, Lyrocarpa, and Synthlipsis)and PP (Paysonia and Physaria). New analyses also increased internal resolution for some closely related species and lineages within both clades. The monophyly of Dithyrea and the sister relationship of Paysonia to Physaria was consistent in all trees, with the sister relationship of Nerisyrenia to Lyrocarpa supported by ndhF and ITS, and the positions of Dimorphocarpa and Synthlipsis shifted within the DDNLS Clade depending on the employed data set. Finally, using the strong, new phylogenetic framework of combined cpDNA + nDNA data, we discussed standing hypotheses of trichome evolution in the tribe suggested by ndhF.


The Auk ◽  
2007 ◽  
Vol 124 (1) ◽  
pp. 71-84 ◽  
Author(s):  
W. Andrew Cox ◽  
Rebecca T. Kimball ◽  
Edward L. Braun

Abstract The evolutionary relationship between the New World quail (Odontophoridae) and other groups of Galliformes has been an area of debate. In particular, the relationship between the New World quail and guineafowl (Numidinae) has been difficult to resolve. We analyzed >8 kb of DNA sequence data from 16 taxa that represent all major lineages of Galliformes to resolve the phylogenetic position of New World quail. A combined data set of eight nuclear loci and three mitochondrial regions analyzed with maximum parsimony, maximum likelihood, and Bayesian methods provide congruent and strong support for New World quail being basal members of a phasianid clade that excludes guineafowl. By contrast, the three mitochondrial regions exhibit modest incongruence with each other. This is reflected in the combined mitochondrial analyses that weakly support the Sibley-Ahlquist topology that placed the New World quail basal in relation to guineafowl and led to the placement of New World quail in its own family, sister to the Phasianidae. However, simulation-based topology tests using the mitochondrial data were unable to reject the topology suggested by our combined (mitochondrial and nuclear) data set. By contrast, similar tests using our most likely topology and our combined nuclear and mitochondrial data allow us to strongly reject the Sibley-Ahlquist topology and a topology based on morphological data that unites Old and New World quail. Posición Filogenética de las Codornices del Nuevo Mundo (Odontophoridae): Ocho Loci Nucleares y Tres Regiones Mitocondriales Contradicen la Morfología y la Filogenia de Sibley y Ahlquist


2009 ◽  
Vol 34 (3) ◽  
pp. 580-594 ◽  
Author(s):  
Anthony R. Magee ◽  
Ben-Erik van Wyk ◽  
Patricia M. Tilney ◽  
Stephen R. Downie

Generic circumscriptions and phylogenetic relationships of the Cape genera Capnophyllum, Dasispermum, and Sonderina are explored through parsimony and Bayesian inference analyses of nrDNA ITS and cpDNA rps16 intron sequences, morphology, and combined molecular and morphological data. The relationship of these genera with the North African genera Krubera and Stoibrax is also assessed. Analyses of both molecular data sets place Capnophyllum, Dasispermum, Sonderina, and the only southern African species of Stoibrax (S. capense) within the newly recognized Lefebvrea clade of tribe Tordylieae. Capnophyllum is strongly supported as monophyletic and is distantly related to Krubera. The monotypic genus Dasispermum and Stoibrax capense are embedded within a paraphyletic Sonderina. This complex is distantly related to the North African species of Stoibrax in tribe Apieae, in which the type species, Stoibrax dichotomum, occurs. Consequently, Dasispermum is expanded to include both Sonderina and Stoibrax capense. New combinations are formalized for Dasispermum capense, D. hispidum, D. humile, and D. tenue. An undescribed species from the Tanqua Karoo in South Africa is also closely related to Capnophyllum and the Dasispermum–Sonderina complex. The genus Scaraboides is described herein to accommodate the new species, S. manningii. This monotypic genus shares the dorsally compressed fruit and involute marginal wings with Capnophyllum, but is easily distinguished by its erect branching habit, green leaves, scabrous umbels, and fruit with indistinct median and lateral ribs, additional solitary vittae in each marginal wing, and parallel, closely spaced commissural vittae. Despite the marked fruit similarities with Capnophyllum, analyses of DNA sequence data place Scaraboides closer to the Dasispermum–Sonderina complex, with which it shares the erect habit, green (nonglaucous) leaves, and scabrous umbels.


1995 ◽  
Vol 347 (1320) ◽  
pp. 213-234 ◽  

Phylogenedc reladonships of higher taxa of echinoids have been invesdgated using a 163 character morphological data base and molecular sequences from large and small subunit (LSU and SSU) ribosomal RNA (rRNA) genes. The complete ssu rRNA gene has been sequenced for 21 taxa, with representatives from nine of the 14 extant orders of Echinoidea. Partial LSU sequences, representing the first 400 base pairs (b.p.) from the 5' end were also sequenced for three taxa to complement an existing data base of ten taxa. The two molecular sequences provided a total of 371 variable sites, of which 143 were phylogenetically informative (compared to 145 phylogenetically informative sites from morphological data). Morphological, LSU and SSU data have been analysed separately and together. Morphological and ssu sequence data generate topologies that are not significantly in conflict (under Templeton’s test), but the strong signal pairing arbaciids with clypeasteroids in the LSU derived tree marks the LSU sequence data as anomalous for this taxon. A ‘ total evidence’ approach derived a tree very similar in topology to that derived from morphological data. Rooted on the stem group echinoid Archaeocidaris , our total evidence tree suggested relationships of higher taxa as follows: Gidaroida Phormosomatidae Echinothuriidae Diadematidae Spatangoida Clypeasteroida, Cassiduloida Calycina, Arbacioida Stomopneustidae Glyphocidaridae Temnopleuridae Echinometridae Echinidae, Strongylocentridae. Phylogenetic analyses run both with and without key fossil taxa yielded slightly different topologies. It is important to include fossil taxa in a phylogenetic analysis where there are long stem-group branches or where the crown group is highly derived.


2018 ◽  
Vol 285 (1874) ◽  
pp. 20172081 ◽  
Author(s):  
Paola Pulido-Santacruz ◽  
Alexandre Aleixo ◽  
Jason T. Weir

We possess limited understanding of how speciation unfolds in the most species-rich region of the planet—the Amazon basin. Hybrid zones provide valuable information on the evolution of reproductive isolation, but few studies of Amazonian vertebrate hybrid zones have rigorously examined the genome-wide underpinnings of reproductive isolation. We used genome-wide genetic datasets to show that two deeply diverged, but morphologically cryptic sister species of forest understorey birds show little evidence for prezygotic reproductive isolation, but substantial postzygotic isolation. Patterns of heterozygosity and hybrid index revealed that hybrid classes with heavily recombined genomes are rare and closely match simulations with high levels of selection against hybrids. Genomic and geographical clines exhibit a remarkable similarity across loci in cline centres, and have exceptionally narrow cline widths, suggesting that postzygotic isolation is driven by genetic incompatibilities at many loci, rather than a few loci of strong effect. We propose Amazonian understorey forest birds speciate slowly via gradual accumulation of postzygotic genetic incompatibilities, with prezygotic barriers playing a less important role. Our results suggest old, cryptic Amazonian taxa classified as subspecies could have substantial postzygotic isolation deserving species recognition and that species richness is likely to be substantially underestimated in Amazonia.


Phytotaxa ◽  
2021 ◽  
Vol 516 (3) ◽  
Author(s):  
KURTULUŞ ÖZGİŞİ ◽  
BURCU TARIKAHYA-HACIOĞLU

Symphytum is regarded one of the most complicated genera in terms of the classification of its members among the Boraginaceae. In addition to different infrageneric classification methods, several species complex or aggregates have been proposed to deal with the taxonomical problem of genus members. Symphytum asperum aggregate was first introduced by Kurtto, who proposed six taxa within this aggregate. However, according to further studies by different researchers based on morphological data, total number of species of the complex was variable. The number of species was reduced to three, comprising S. asperum, S. savvalense, and S. sylvaticum, after the phylogenetic and morphological studies of Tarıkahya-Hacıoğlu and Erik. However, the taxonomical status of some of these species (i.e., S. savvalense and S. sylvaticum, and S. sepulcrale), which was assigned as a member of this complex by Kurtto, has been regarded as unresolved. To solve this uncertainty, different species delimitation methods were used, including statistical parsimony network analysis (TCS), generalized mixed Yule coalescent (GMYC), and Bayesian Phylogenetics and Phylogeography (BPP) of the ITS, trnL-F and trnS-G sequence data. In addition to members of this complex, S. ibericum, which is phylogenetically nested within the S. asperum aggregate, was also used. The TCS and GMYC analyses demonstrated more complicated clusters, whereas high posterior probabilities of BPP clusters were more compatible with the morphological data. In accordance with the morphological approach of Tarıkahya-Hacıoğlu and Erik, the species delimitation analyses based on molecular data support the recognition of S. asperum, S. ibericum, S. savvalense, and S. sylvaticum as different species.


Zootaxa ◽  
2009 ◽  
Vol 1991 (1) ◽  
pp. 28-42 ◽  
Author(s):  
T. HEATH OGDEN ◽  
JONATHAN T. OSBORNE ◽  
LUKE M. JACOBUS ◽  
MICHAEL F. WHITING

This study represents the first combined molecular and morphological analysis for the mayfly family Ephemerellidae (Ephemeroptera), with a focus on the relationships of genera and species groups of the subfamily Ephemerellinae. The phylogeny was constructed based on DNA sequence data from 3 nuclear (18S rDNA, 28S rDNA, histone H3) and 2 mitochondrial (12S rDNA, 16S rDNA) genes, and 23 morphological characters. Taxon sampling for Ephemerellidae included exemplars from all 25 extant genus groups and additional representatives from those genera with the highest diversity. Ephemerellidae appears to consist of three major clades. Ephemerella, the largest genus of Ephemerellidae, and Serratella were not supported as monophyletic, and each had representatives in two of the three major clades. However, the genera Drunella and Cincticostella were supported as monophyletic. Lineages strongly supported as monophyletic include a grouping of the Timpanoginae genera Timpanoga, Dannella, Dentatella and Eurylophella, and groupings of the Ephemerellinae genera Torleya, Hyrtanella and Crinitella and the genera Kangella, Uracanthella and Teloganopsis. The placement of the Timpanoginae genus Attenella fell within Ephemerellinae, based on molecular and combined data, but it grouped with other Timpanoginae based on morphological data alone. Further study and analysis of Ephemerellidae morphology is needed, and classification should be revised, if it is to reflect phylogenetic relationships.


Sign in / Sign up

Export Citation Format

Share Document