Abstract
Tibetia and Gueldenstaedtia are two morphologically similar and small genera in Fabaceae, with distributions largely corresponding to the Sino-Himalayan and Sino-Japanese subkingdoms in eastern Asia, respectively. These two genera have confusing relationships based on morphology; therefore, we aimed to provide a clear understanding of their phylogenetic and biogeographic evolution within eastern Asia. In our investigations we included 88 samples representing five Gueldenstaedtia species, five Tibetia species, and outgroup species were sequenced using five markers (nuclear: ITS; chloroplast: matK, trnL-F, psbA-trnH and rbcL). Our phylogenetic results support (1) the monophyly of Tibetia and of Gueldenstaedtia, respectively; and (2) that Tibetia and Gueldenstaedtia are sister genera. Additionally, our data identified that Tibetia species had much higher sequence variation than Gueldenstaedtia species. Our results suggest that the two genera were separated from each other about 17.23 million years ago, which is congruent with the Himalayan orogeny and the uplift of the Tibetan Plateau in the mid Miocene. The divergence of Tibetia and Gueldenstaedtia is strongly supported by the separation of the Sino-Himalayan and Sino-Japanese region within eastern Asia. In addition, the habitat heterogeneity may accelerate the molecular divergence of Tibetia in the Sino-Himalayan region.
Highlights
Gueldenstaedtia Fischer is a small genus in the legume family (Fabaceae) which was named by F
Incongruence was detected between nuclear and plastid sequences (ILD, P < 0.05), whether the conflicting data sets could be combined in a simultaneous analysis is a complex and controversial decision [47,48]
Tibetia are endemic to the Hengduan Mountain region (i.e. Sino-Himalayan subkingdom), and its prostrate habit and dense glandular hair might be an adaptation to the high-altitude plateau
Summary
Gueldenstaedtia Fischer is a small genus in the legume family (Fabaceae) which was named by F. E. Fischer to pay tribute to the Russian naturalist Gueldenstaedt [1]. Fischer to pay tribute to the Russian naturalist Gueldenstaedt [1] This genus has usually been divided into two subgenera based on morphological characteristics of the stipules, style, and seeds: subgenera Gueldenstaedtia and Tibetia [2]. Species in subgenus Gueldenstaedtia are characterized by lateral stipules that are not leaf-opposed, free from each other, and seeds that are glazed, pitted, uniformly colored, and never spotted. Species in subgenus Tibetia has stipules that are amplexicaul, leaf-opposed, and united at least in the young condition, and seeds that are unglazed, never pitted, and have irregular blackish spots (Table 1)
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