Karyotypic variation in Nicotiana section Suaveolentes

Marks, Claire E.; Ladiges, Pauline Y.; Newbigin, Ed

doi:10.1007/s10722-011-9724-3

Cited by 18 publications

(18 citation statements)

References 23 publications

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“…Some allopolyploids are recent and have no close polyploid relatives, whereas others appear to be much older and numerous, the result of speciation at the polyploid level. Polyploidy and diploidisation have been the subject of study in the genus for around two decades: chromosome arm translocations (Lim et al 2004), homoploid hybridisation , intergenic recombination , concerted evolution , long-term diploidisation of genomic repeats (Clarkson et al 2005;Dodsworth et al 2016a), progenitor determination (Kelly et al 2013), maternal genome donors , elimination of genomic repeats (Renny-Byfield et al 2011), the phylogenetic signal in repeats (Dodsworth et al 2015(Dodsworth et al , 2016b, floral evolution (McCarthy et al 2015), morphological character evolution (Marks et al 2011a;McCarthy et al 2016), biogeography (Ladiges et al 2011) and genome size changes (Leitch et al 2008). An earlier paper (Clarkson et al 2005) focused on the timing of polyploid events for a subset of polyploids in Nicotiana, using nonparametric rate smoothing (NPRS), but recent advances in molecular clock analysis make another study of this subject in the genus as a whole timely.…”

Section: Polyploidy In Nicotianamentioning

confidence: 99%

Time-calibrated phylogenetic trees establish a lag between polyploidisation and diversification in Nicotiana (Solanaceae)

2017

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We investigate the timing of diversification in allopolyploids of Nicotiana (Solanaceae) utilising sequence data of maternal and paternal origin to look for evidence of a lag phase during which diploidisation took place. Bayesian relaxed clock phylogenetic methods show recent allopolyploids are a result of several unique polyploidisation events, and older allopolyploid sections have undergone subsequent speciation at the polyploid level (i.e. a number of these polyploid species share a singular origin). The independently formed recent polyploid species in the genus all have mean age estimates below 1 million years ago (Ma). Nicotiana section Polydicliae (two species) evolved 1.5 Ma, N. section Repandae (four species) formed 4 Ma, and N. section Suaveolentes (*35 species) is about 6 million years old. A general trend of higher speciation rates in older polyploids is evident, but diversification dramatically increases at approximately 6 Ma (in section Suaveolentes). Nicotiana sect. Suaveolentes has spectacularly radiated to form 35 species in Australia and some Pacific islands following a lag phase of almost 6 million years. Species have filled new ecological niches and undergone extensive diploidisation (e.g. chromosome fusions bringing the ancestral allotetraploid number, n = 24, down to n = 15 and ribosomal loci numbers back to diploid condition). Considering the progenitors of Suaveolentes inhabit South America, this represents the colonisation of Australia by polyploids that have subsequently undergone a recent radiation into new environments. To our knowledge, this study is the first report of a substantial lag phase being investigated below the family level.

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Section: Polyploidy In Nicotianamentioning

confidence: 99%

Time-calibrated phylogenetic trees establish a lag between polyploidisation and diversification in Nicotiana (Solanaceae)

2017

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“…Counts were recorded from the literature (Wheeler 1945;Goodspeed 1954;Burbidge 1960;Merxmüller and Buttler 1975;Williams 1975;Horton 1981;Symon 1984Symon , 1998Clarkson and Symon 1991;Symon and Kenneally 1994;Laskowska and Berbec 2003), and from root squashes of freshly grown material for 20 taxa, the latter providing new counts and checks of older records (Marks 2010b).…”

Section: Chromosome Numbermentioning

confidence: 99%

Comparative morphology and phylogeny of Nicotiana section Suaveolentes (Solanaceae) in Australia and the South Pacific

Marks

Newbigin

Ladiges

2011

Aust. Systematic Bot.

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Abstract. Molecular phylogenies alone have failed to resolve evolutionary relationships of Nicotiana L. section Suaveolentes Goodsp. (Solanaceae), a section largely comprising Australian endemics. Comparative morphology of Suaveolentes is illustrated and characters, together with the chromosome number, coded for phylogenetic analysis. Morphological characters included discrete characters of seeds and trichomes studied by scanning electron and light microscopy, and gap-coded quantitative measurements of flowers and vegetative organs. These data were analysed using both maximum parsimony and splits network, and compared to and combined with molecular analyses based on published nuclear and chloroplast-DNA sequences. Among morphological characters, there was a high level of homoplasy, possibly attributable to convergent evolution, hybridisation and introgression, and the underlying polyploid origin of the group. There was some conflict between the morphological and molecular datasets; however, overall there was a level of concordance that identified a phylogenetic sequence of taxa that reflected a reduction in the chromosome number.

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“…Nicotiana sect. Suaveolentes has also been the focus of recent studies aimed at analyzing karyotypic variation, morphology, and biogeography of these species (Ladiges et al 2011; Marks et al 2011a,b).…”

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confidence: 99%

RECONSTRUCTING THE COMPLEX EVOLUTIONARY ORIGIN OF WILD ALLOPOLYPLOID TOBACCOS (NICOTIANASECTIONSUAVEOLENTES)

et al. 2012

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Nicotiana (Solanaceae) provides an ideal system for understanding polyploidization, a pervasive and powerful evolutionary force in plants, as this genus contains several groups of allotetraploids that formed at different times from different diploid progenitors.However, the parental lineages of the largest group of allotetraploids, Nicotiana section Suaveolentes, have been problematic to identify. Using data from four regions of three low-copy nuclear genes, nuclear ribosomal DNA, and regions of the plastid genome, we have reconstructed the evolutionary origin of sect. Suaveolentes and identified the most likely diploid progenitors by using a combination of gene trees and network approaches to uncover the most strongly supported evidence of species relationships. Our analyses best support a scenario where a member of the sect. Sylvestres lineage acted as the paternal progenitor and a member of either sect. Petunioides or sect. Noctiflorae that also contained introgressed DNA from the other, or a hypothetical hybrid species between these two sections, was the maternal progenitor. Nicotiana exemplifies many of the factors that can complicate the reconstruction of polyploid evolutionary history and highlights how reticulate evolution at the diploid level can add even greater complexity to allopolyploid genomes.

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Karyotypic variation in Nicotiana section Suaveolentes

Cited by 18 publications

References 23 publications

Time-calibrated phylogenetic trees establish a lag between polyploidisation and diversification in Nicotiana (Solanaceae)

Time-calibrated phylogenetic trees establish a lag between polyploidisation and diversification in Nicotiana (Solanaceae)

Comparative morphology and phylogeny of Nicotiana section Suaveolentes (Solanaceae) in Australia and the South Pacific

RECONSTRUCTING THE COMPLEX EVOLUTIONARY ORIGIN OF WILD ALLOPOLYPLOID TOBACCOS (NICOTIANASECTIONSUAVEOLENTES)

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