Morphology and anatomy of the exine in Saxifraga (Saxifragaceae)

Zhang, Zhuoxin; Chen, Shilong; Gornall, R. J.

doi:10.11646/phytotaxa.212.2.1

Cited by 10 publications

(5 citation statements)

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“…Unique morphological synapomorphies of this section, however, are hard to find. The feature that comes closest is the sculpturing of the pollen exine, which is finely striate in all but two species (Zhang Z.-X. & al., 2015).…”

Section: Discussionmentioning

confidence: 99%

Phylogeny and speciation in Saxifraga sect. Ciliatae (Saxifragaceae): Evidence from psbA‐trnH, trnL‐F and ITS sequences

Gao

Gornall

et al. 2015

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Nearly half of the species in the large genus Saxifraga belong to Saxifraga sect. Ciliatae, a largely Sino‐Himalayan taxon. We report here that evidence from chloroplast DNA sequences (psbA‐trnH, trnL‐F) and from nuclear sequences (ITS) indicates that this section is monophyletic and composed of at least three main lineages, corresponding to (1) a clade made up of species from S. subsect. Gemmiparae, subsect. Cinerascentes, subsect. Flagellares and subsect. Hemisphaericae, in which the last three subsections are nested in the first; (2) a clade of species belonging to S. subsect. Rosulares (including S. subsect. Serpyllifoliae); and (3) a clade of species belonging to S. subsect. Hirculoideae. Species relationships in S. subsect. Rosulares and subsect. Hirculoideae are not well resolved. A molecular clock analysis indicates that the diversification of S. sect. Ciliatae into its three lineages dates from ca. 9.48 Ma, coinciding with orogenic events associated with one of the most important phases of uplift of the Qinghai‐Tibet Plateau. Extensive diversifications within S. subsect. Rosulares and subsect. Hirculoideae have been more recent (ca. 4.51 Ma and 2.12 Ma, respectively), again correlated with Qinghai‐Tibet Plateau uplift events and, in the case of S. subsect. Hirculoideae, have occurred at a rate comparable to that seen in the radiation of Hawaiian fruit flies.

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Section: Discussionmentioning

confidence: 99%

Phylogeny and speciation in Saxifraga sect. Ciliatae (Saxifragaceae): Evidence from psbA‐trnH, trnL‐F and ITS sequences

Gao

Gornall

et al. 2015

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“…Any sampling bias is likely to affect the accuracy of rate estimates [69], so we specified section-specific sampling fractions to account for incomplete taxon sampling. However, given that published species numbers for some sections differ widely (Additional file 6, e.g., [26, 30, 70, 71]), we calculated sampling fractions for minimum and maximum published species numbers per section and ran all analyses with both values.…”

Section: Methodsmentioning

confidence: 99%

Evolutionary radiations in the species-rich mountain genus Saxifraga L.

et al. 2017

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BackgroundA large number of taxa have undergone evolutionary radiations in mountainous areas, rendering alpine systems particularly suitable to study the extrinsic and intrinsic factors that have shaped diversification patterns in plants. The species-rich genus Saxifraga L. is widely distributed throughout the Northern Hemisphere, with high species numbers in the regions adjacent to the Qinghai-Tibet Plateau (QTP) in particular the Hengduan Mountains and the Himalayas. Using a dataset of 297 taxa (representing at least 60% of extant Saxifraga species), we explored the variation of infrageneric diversification rates. In addition, we used state-dependent speciation and extinction models to test the effects of geographic distribution in the Hengduan Mountains and the entire QTP region as well as of two morphological traits (cushion habit and specialized lime-secreting glands, so-called hydathodes) on the diversification of this genus.ResultsWe detected two to three rate shifts across the Saxifraga phylogeny and two of these shifts led to radiations within two large subclades of Saxifraga, sect. Ciliatae Haworth subsect. Hirculoideae Engl. & Irmsch. and sect. Porphyrion Tausch subsect. Kabschia Engl. GEOSSE analyses showed that presence in the Hengduan Mountains had a positive effect on diversification across Saxifraga. Influence of these mountains was strongest in Saxifraga sect. Ciliatae subsect. Hirculoideae given its pronounced distribution there, and thus the radiation in this group can be classified at least partially as geographic. In contrast, the evolution of the cushion life form and lime-secreting hydathodes had positive effects on diversification only in selected Saxifraga sections, including sect. Porphyrion subsect. Kabschia. We therefore argue that radiation in this group was likely adaptive.ConclusionsOur study underlines the complexity of processes and factors underpinning plant radiations: Even in closely related lineages occupying the same life zone, shifts in diversification are not necessarily governed by similar factors. In conclusion, alpine plant radiations result from a complex interaction among geographical settings and/or climatic modifications providing key opportunities for diversification as well as the evolution of key innovations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0967-2) contains supplementary material, which is available to authorized users.

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“…S. sect. Irregulares Haw., characterized by zygomorphic flowers with two elongated petals and stamens with club-shaped filaments (Tkach et al 2015b), is the ancestral clade of Saxifraga first described by Haworth (Haworth 1803; Soltis et al 2001;Zhang et al 2015;Tkach et al 2015b;Zhang et al 2019b). This section currently comprises 16 species mainly distributed in East Asia (Magota et al 2021).…”

Section: Introductionmentioning

confidence: 99%