Non-adaptive hypothesis of allopatric cytotype distribution inMyosotis lamottiana (Boraginaceae)

Štěpánková, Jitka

doi:10.1007/bf02803159

Cited by 10 publications

(6 citation statements)

References 24 publications

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“…Limonium ) also presented frequency values above the average. Despite no exhaustive study being made to evaluate the frequency of polyploidy in such families or genera, there are several pieces of evidence in the literature that support our estimations (Štěpánková ; Castro & Rosselló ; Caperta et al . ).…”

Section: Hybridisation and Polyploidy In The Mediterranean Regionsupporting

confidence: 65%

How much do we know about the frequency of hybridisation and polyploidy in the Mediterranean region?

et al. 2017

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Natural hybridisation and polyploidy are currently recognised as drivers of biodiversity, despite early scepticism about their importance. The Mediterranean region is a biodiversity hotspot where geological and climatic events have created numerous opportunities for speciation through hybridisation and polyploidy. Still, our knowledge on the frequency of these mechanisms in the region is largely limited, despite both phenomena are frequently cited in studies of Mediterranean plants. We reviewed information available from biodiversity and cytogenetic databases to provide the first estimates of hybridisation and polyploidy frequency in the Mediterranean region. We also inspected the most comprehensive modern Mediterranean Flora (Flora iberica) to survey the frequency and taxonomic distribution of hybrids and polyploids in Iberian Peninsula. We found that <6% of Mediterranean plants were hybrids, although a higher frequency was estimated for the Iberian Peninsula (13%). Hybrids were concentrated in few families and in even fewer genera. The overall frequency of polyploidy (36.5%) was comparable with previous estimates in other regions; however our estimates increased when analysing the Iberian Peninsula (48.8%). A surprisingly high incidence of species harbouring two or more ploidy levels was also observed (21.7%). A review of the available literature also showed that the ecological factors driving emergence and establishment of new entities are still poorly studied in the Mediterranean flora, although geographic barriers seem to play a major role in polyploid complexes. Finally, this study reveals several gaps and limitations in our current knowledge about the frequency of hybridisation and polyploidy in the Mediterranean region. The obtained estimates might change in the future with the increasing number of studies; still, rather than setting the complete reality, we hope that this work triggers future studies on hybridisation and polyploidy in the Mediterranean region.

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Section: Hybridisation and Polyploidy In The Mediterranean Regionsupporting

confidence: 65%

How much do we know about the frequency of hybridisation and polyploidy in the Mediterranean region?

et al. 2017

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“…The allopolyploid interpretation for the origin of P. marginata dodecaploids might appear to conflict with their lack of morphological differentiation [25,34; Casazza, unpublished observations]. Our case study might represent an example where the allopolyploids resemble one of the putative parental lineages, a situation that has been found also in Mimulus [ 69 ] and Centaurea toletana [ 70 ]; as reviewed in [ 10 ] and is compatible with the non-adaptive scenario [ 43 , 44 ] proposed above to explain the geographic separation between hexaploid and dodecaploid populations.…”

Section: Discussionsupporting

confidence: 53%

“…In the non-adaptive scenario, hybridization between cytotypes is thought to be either non-viable or produce plants with lower fitness, gradually leading to the elimination of the minority cytotype through frequency-dependent mechanisms (‘minority cytotype exclusion model’, [ 42 ]). These non-adaptive processes, while producing cytological uniformity, promote differentiation in a stochastic manner that does not usually produce distinct morphological and ecological characteristics [ 43 , 44 ]. In P. marginata the lack of morphological distinctiveness of the two cytotypes [ 25 ] and the absence of any obvious new ecological preferences in the dodecaploids [ 34 ] all fit the predictions of the non-adaptive scenario.…”

Section: Discussionmentioning

confidence: 99%

Polyploid evolution and Pleistocene glacial cycles: A case study from the alpine primrose Primula marginata (Primulaceae)

et al. 2012

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BackgroundRecent studies highlighted the role of Pleistocene climatic cycles in polyploid speciation and of southern Alpine refugia as reservoirs of diversity during glacial maxima. The polyploid Primula marginata, endemic to the southwestern Alps, includes both hexaploid and dodecaploid cytotypes that show no ecological or morphological differences. We used flow cytometry to determine variation and geographic distribution of cytotypes within and between populations and analyses of chloroplast (cp) and nuclear ribosomal (nr) DNA sequences from the Internal Transcribed Spacer (ITS) region to infer the evolutionary history of the two cytotypes and the auto- vs. allopolyploid origin of dodecaploid populations.ResultsWe did not detect any intermediate cytotypes or variation of ploidy levels within populations. Hexaploids occur in the western and dodecaploids in the eastern part of the distributional range, respectively. The cpDNA and nrDNA topologies are in conflict, for the former supports shared ancestry between P. marginata and P. latifolia, while the latter implies common origins between at least some ITS clones of P. marginata and P. allionii.ConclusionsOur results suggest an initial episode of chloroplast capture involving ancestral lineages of P. latifolia and P. marginata, followed by polyploidization between P. marginata-like and P. allionii-like lineages in a southern refugium of the Maritime Alps. The higher proportion of ITS polymorphisms in dodecaploid than in hexaploid accessions of P. marginata and higher total nucleotide diversity of ITS clones in dodecaploid vs. hexaploid individuals sequences are congruent with the allopolyploid hypothesis of dodecaploid origin.

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“…Other cytobiogeographical studies have also failed to find evidence that polyploid species occupy more extreme environments (Tyler et al, 1978; Stutz and Sanderson, 1983; Gauthier et al, 1998; Hardy et al, 2000; Schönswetter et al, 2007; Martin and Husband, 2009; Laport et al, 2012; Glennon et al, 2014). Moreover, experimental approaches have failed to reveal polyploid species occupying wider niches (Stebbins and Dawe, 1987; Petit and Thompson, 1999; Martin and Husband, 2009; Glennon et al, 2012; Theodoridis et al, 2013; Harbert et al, 2014) or distinct niches from their lower‐ploidy progenitors (Štěpánková, 2001; Baack and Stanton, 2005; Mandáková and Münzbergová, 2006; Glennon et al, 2012, 2014; Godsoe et al, 2013). These studies, in addition to our findings, suggest that these hypotheses are not universally upheld, therefore suggesting that more mechanistic studies will be required to understand how WGD influences ecological niches.…”

Section: Discussionmentioning

confidence: 99%

Ecological niche differentiation of polyploidization is not supported by environmental differences among species in a cosmopolitan grass genus

Visser

Molofsky

2015

American J of Botany

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Our results suggest that these commonly held hypotheses about the effects of polyploidization on ecological distributions are not universally applicable. Correlative biogeographic studies like ours provide a necessary first step for suggesting specific hypotheses that require experimental verification. A combination of genetic, physiological, and ecological studies will be required to achieve a better understanding of the role of polyploidization in niche evolution.

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Non-adaptive hypothesis of allopatric cytotype distribution inMyosotis lamottiana (Boraginaceae)

Cited by 10 publications

References 24 publications

How much do we know about the frequency of hybridisation and polyploidy in the Mediterranean region?

How much do we know about the frequency of hybridisation and polyploidy in the Mediterranean region?

Polyploid evolution and Pleistocene glacial cycles: A case study from the alpine primrose Primula marginata (Primulaceae)

Ecological niche differentiation of polyploidization is not supported by environmental differences among species in a cosmopolitan grass genus

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