• Phylogenetic relationships of Gaultheria series Trichophyllae are reconstructed with plastid phylogenomic analyses.
• Eight sequence divergence hotspot regions are screened across the plastid genomes of the studied individuals.
• Morphological characters important for species delimitation in G. series Trichophyllae are traced onto the phylogeny.
Gaultheria series Trichophyllae Airy Shaw is an angiosperm clade of high-alpine shrublets endemic to the Himalaya-Hengduan Mountains and characterized by recent species divergence and convergent character evolution that has until recently caused much confusion in species circumscription. Although multiple DNA sequence regions have been employed previously, phylogenetic relationships among species in the group have remained largely unresolved. Here we examined the effectiveness of the plastid genome for improving phylogenetic resolution within the G. series Trichophyllae clade. Plastid genomes of 31 samples representing all 19 recognized species of the series and three outgroup species were sequenced with Illumina Sequencing technology. Maximum likelihood (ML), maximum parsimony (MP) and Bayesian inference (BI) phylogenetic analyses were performed with various datasets, i.e., that from the whole plastid genome, coding regions, noncoding regions, large single-copy region (LSC) and inverted-repeat region a (IRa). The partitioned whole plastid genome with inverted-repeat region b (IRb) excluded was also analyzed with ML and BI. Tree topologies based on the whole plastid genome, noncoding regions, and LSC region datasets across all analyses, and that based on the partitioned dataset with ML and BI analyses, are identical and generally strongly supported. Gaultheria series Trichophyllae form a clade with three species and one variety that is sister to a clade of the remaining 16 species; the latter comprises seven main subclades. Interspecific relationships within the series are strongly supported except for those based on the coding-region and IRa-region datasets. Eight divergence hotspot regions, each possessing >5% percent variable sites, were screened across the whole plastid genome of the 28 individuals sampled in the series. Results of morphological character evolution reconstruction diagnose several clades, and a hypothesis of adaptive evolution for plant habit is postulated.
Keywords: Plastid genome; Character evolution; Gaultheria; Phylogenetic relationships
Ming-Ying Zhang, Peter W. Fritsch, Peng-Fei Ma, Hong Wang, Lu Lu and De-Zhu Li. 2017. Plastid Phylogenomics and Adaptive Evolution of Gaultheria series Trichophyllae (Ericaceae), A Clade from Sky Islands of the Himalaya-Hengduan Mountains. Molecular Phylogenetics and Evolution. 110; 7–18. DOI: 10.1016/j.ympev.2017.01.015