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Cytotype diversity and genome size variation in Knautia (Caprifoliaceae, Dipsacoideae).

Frajman B, Rešetnik I, Weiss-Schneeweiss H, Ehrendorfer F, Schönswetter P - BMC Evol. Biol. (2015)

Bottom Line: We show that the frequency of polyploidisation is unevenly distributed in Knautia both in a geographic and phylogenetic context.Monoploid GS varies considerably among three evolutionary lineages (sections) of Knautia, but also within sections Trichera and Tricheroides, as well as within some of the species.Although the exact causes of this variation remain elusive, we demonstrate that monoploid GS increases significantly towards the limits of the genus' distribution.

View Article: PubMed Central - PubMed

Affiliation: Institute of Botany, University of Innsbruck, Sternwartestraße 15, A-6020, Innsbruck, Austria.

ABSTRACT

Background: Polyploidisation is one of the most important mechanisms in the evolution of angiosperms. As in many other genera, formation of polyploids has significantly contributed to diversification and radiation of Knautia (Caprifoliaceae, Dipsacoideae). Comprehensive studies of fine- and broad-scale patterns of ploidy and genome size (GS) variation are, however, still limited to relatively few genera and little is known about the geographic distribution of ploidy levels within these genera. Here, we explore ploidy and GS variation in Knautia based on a near-complete taxonomic and comprehensive geographic sampling.

Results: Genome size is a reliable indicator of ploidy level in Knautia, even if monoploid genome downsizing is observed in the polyploid cytotypes. Twenty-four species studied are diploid, 16 tetraploid and two hexaploid, whereas ten species possess two, and two species possess three ploidy levels. Di- and tetraploids are distributed across most of the distribution area of Knautia, while hexaploids were sampled in the Balkan and Iberian Peninsulas and the Alps.

Conclusions: We show that the frequency of polyploidisation is unevenly distributed in Knautia both in a geographic and phylogenetic context. Monoploid GS varies considerably among three evolutionary lineages (sections) of Knautia, but also within sections Trichera and Tricheroides, as well as within some of the species. Although the exact causes of this variation remain elusive, we demonstrate that monoploid GS increases significantly towards the limits of the genus' distribution.

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Related in: MedlinePlus

Geographical distribution of cytotypes in the genus Knautia. Circles: diploids; triangles: tetraploids; squares: hexaploids; colors denote taxa according to the individual legends inside each panel.
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Fig6: Geographical distribution of cytotypes in the genus Knautia. Circles: diploids; triangles: tetraploids; squares: hexaploids; colors denote taxa according to the individual legends inside each panel.

Mentions: Diploid and tetraploid populations of different species occur across most of the distribution area of Knautia, whereas hexaploid populations exhibit a more restricted distribution in the Balkans (central Dinaric Mountains), the Alps (extra-Alpine populations of K. dipsacifolia were not sampled) and the Iberian Peninsula (two populations of K. rupicola in eastern Spain; Figs. 6, 7). The monoploid RGS of di- and tetraploid individuals is smaller in the western Balkan Peninsula and the Alps and increases towards the eastern, western and southern margins of the genus’ distribution area in diploids, and towards the western and northern margins in tetraploids and hexaploids (rs = 0.405, rs = 0.656, and rs = 0.671 p < 0.01 for diploids, tetraploids and hexaploids, respectively; Fig. 7).Fig. 6


Cytotype diversity and genome size variation in Knautia (Caprifoliaceae, Dipsacoideae).

Frajman B, Rešetnik I, Weiss-Schneeweiss H, Ehrendorfer F, Schönswetter P - BMC Evol. Biol. (2015)

Geographical distribution of cytotypes in the genus Knautia. Circles: diploids; triangles: tetraploids; squares: hexaploids; colors denote taxa according to the individual legends inside each panel.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4504173&req=5

Fig6: Geographical distribution of cytotypes in the genus Knautia. Circles: diploids; triangles: tetraploids; squares: hexaploids; colors denote taxa according to the individual legends inside each panel.
Mentions: Diploid and tetraploid populations of different species occur across most of the distribution area of Knautia, whereas hexaploid populations exhibit a more restricted distribution in the Balkans (central Dinaric Mountains), the Alps (extra-Alpine populations of K. dipsacifolia were not sampled) and the Iberian Peninsula (two populations of K. rupicola in eastern Spain; Figs. 6, 7). The monoploid RGS of di- and tetraploid individuals is smaller in the western Balkan Peninsula and the Alps and increases towards the eastern, western and southern margins of the genus’ distribution area in diploids, and towards the western and northern margins in tetraploids and hexaploids (rs = 0.405, rs = 0.656, and rs = 0.671 p < 0.01 for diploids, tetraploids and hexaploids, respectively; Fig. 7).Fig. 6

Bottom Line: We show that the frequency of polyploidisation is unevenly distributed in Knautia both in a geographic and phylogenetic context.Monoploid GS varies considerably among three evolutionary lineages (sections) of Knautia, but also within sections Trichera and Tricheroides, as well as within some of the species.Although the exact causes of this variation remain elusive, we demonstrate that monoploid GS increases significantly towards the limits of the genus' distribution.

View Article: PubMed Central - PubMed

Affiliation: Institute of Botany, University of Innsbruck, Sternwartestraße 15, A-6020, Innsbruck, Austria.

ABSTRACT

Background: Polyploidisation is one of the most important mechanisms in the evolution of angiosperms. As in many other genera, formation of polyploids has significantly contributed to diversification and radiation of Knautia (Caprifoliaceae, Dipsacoideae). Comprehensive studies of fine- and broad-scale patterns of ploidy and genome size (GS) variation are, however, still limited to relatively few genera and little is known about the geographic distribution of ploidy levels within these genera. Here, we explore ploidy and GS variation in Knautia based on a near-complete taxonomic and comprehensive geographic sampling.

Results: Genome size is a reliable indicator of ploidy level in Knautia, even if monoploid genome downsizing is observed in the polyploid cytotypes. Twenty-four species studied are diploid, 16 tetraploid and two hexaploid, whereas ten species possess two, and two species possess three ploidy levels. Di- and tetraploids are distributed across most of the distribution area of Knautia, while hexaploids were sampled in the Balkan and Iberian Peninsulas and the Alps.

Conclusions: We show that the frequency of polyploidisation is unevenly distributed in Knautia both in a geographic and phylogenetic context. Monoploid GS varies considerably among three evolutionary lineages (sections) of Knautia, but also within sections Trichera and Tricheroides, as well as within some of the species. Although the exact causes of this variation remain elusive, we demonstrate that monoploid GS increases significantly towards the limits of the genus' distribution.

Show MeSH
Related in: MedlinePlus