Diploid hybrid origin ofHippophaë gyantsensis(Elaeagnaceae) in the western Qinghai-Tibet Plateau

Abstract

Homoploid hybrid speciation, the origin of a hybrid species without change in chromosome number, is currently considered to be a rare form of speciation. In the present study, we examined the phylogenetic origin of Hippophaë gyantsensis, a diploid species occurring in the western Qinghai–Tibet Plateau. Some of its morphological and molecular traits suggest a close relationship to H. rhamnoides ssp. yunnanensis while others indicate H. neurocarpa. We conducted phylogenetic analyses of sequence data of two maternally inherited chloroplast (cp) DNA fragments and the bi‐parentally inherited nuclear ribosomal internal transcribed spacer (ITS) from 17 populations of H. gyantsensis, 15 populations of H. rhamnoides ssp. yunnanensis and 27 populations of H. neurocarpa across their distributional ranges, and modelled the niche differentiation of the three taxa. Multiple lines of evidence suggested that H. gyantsensis is a morphologically stable, genetically independent and ecologically distinct species. The inconsistent phylogenetic placements of the H. gyantsensis clade that comprised the dominant cpDNA haplotypes and ITS ribotypes suggested a probable diploid hybrid origin from multiple crosses between H. rhamnoides ssp. yunnanensis and H. neurocarpa. This tentative hypothesis is more parsimonious than alternative explanations according to the data available, although more evidence based on further testing is needed.

Climatic Changes and Orogeneses in the Late Miocene of Eurasia: The Main Triggers of an Expansion at a Continental Scale?

“…The relationships among the three species within the other sub-clade are still poorly resolved in the cpDNA phylogeny and incongruent between the two data sets. This could probably result from the homoploid hybridizations between species falling into the two sub-clades, i.e., H. neurocarpa and H. rhamnoides , as indicated by our previous work based on population genetic data and niche modeling ( Jia et al, 2016 ).…”

“…This sampling design aimed to obtain representatives across whole ranges and/or main lineages of each taxon, and to allow us robust tests of reciprocal monophyly and ancestral area reconstructions for all taxa. Geographic representation of the main lineages within the following taxa was inferred from the literature: H. tibetana ( Wang et al, 2010 ; Jia et al, 2011 ), H. neurocarpa ( Kou et al, 2013 ), H. gyantsensis ( Jia et al, 2016 ), and H. rhamnoides ssp. yunnanensis and sinensis ( Jia et al, 2012 ).…”

Response to climate change of montane herbaceous plants in the genus Rhodiola predicted by ecological niche modelling

“…yunnanensis , H . neurocarpa , Eriophyton wallichii , Thalictrum squamiferum , Paraquilegia microphylla and Allium przewalskianum also tend towards range expansion with climate warming 38 – 40 . Such patterns may be explained by a number of factors.…”

Species divergence with gene flow and hybrid speciation on the Qinghai–Tibet Plateau

“…Another HHS was revealed for the genetic origin of Hippophae gyantsensis (Elaeagnaceae) from its two parent species. This species occurs in both the Himalaya and the platform region, while the two parents are present on the northeastern platform and Hengduan Mountains and have contrasting niches (Jia et al ., 2016). The hybrid species Picea purpurea and its two parents occur together in the Hengduan Mountains, but still inhabit different niches with respect to both altitude and latitude (Ru et al ., 2018).…”