Phylogeny and biogeography of the genus Stevia (Asteraceae: Eupatorieae): an example of diversification in the Asteraceae in the new world

• Published in: Journal of plant research 2017-11, Vol.130 (6), p.953-972
• Main Authors: Soejima, Akiko, Tanabe, Akifumi S., Takayama, Izumi, Kawahara, Takayuki, Watanabe, Kuniaki, Nakazawa, Miyuki, Mishima, Misako, Yahara, Tetsukazu
• Format: Article
• Language: English
• Subjects: Asteraceae; Asteraceae - classification; Asteraceae - genetics; Biodiversity; Biogeography; Biological Evolution; Biomedical and Life Sciences; Brazil; Coniferous forests; Divergence; DNA, Chloroplast - chemistry; DNA, Chloroplast - genetics; DNA, Intergenic - chemistry; DNA, Intergenic - genetics; DNA, Plant - chemistry; DNA, Plant - genetics; Ecosystem; Forests; Herbs; Life Sciences; Mexico; Migration; Phylogenetics; Phylogeny; Phylogeography; Pine; Plant Biochemistry; Plant Ecology; Plant Physiology; Plant Sciences; Polyploidy; Regular Paper; Sequence Alignment; Sequence Analysis, DNA; Species diversity; Stevia; Stevia - classification; Stevia - genetics
• ISSN: 0918-9440; 1618-0860
• DOI: 10.1007/s10265-017-0955-z

The genus Stevia comprises approximately 200 species, which are distributed in North and South America, and are representative of the species diversity of the Asteraceae in the New World. We reconstructed the phylogenetic relationships using sequences of ITS and cpDNA and estimated the divergence times of the major clade of this genus. Our results suggested that Stevia originated in Mexico 7.0–7.3 million years ago (Mya). Two large clades, one with shrub species and another with herb species, were separated at about 6.6 Mya. The phylogenetic reconstruction suggested that an ancestor of Stevia was a small shrub in temperate pine–oak forests and the evolutionary change from a shrub state to a herb state occurred only once. A Brazilian clade was nested in a Mexican herb clade, and its origin was estimated to be 5.2 Mya, suggesting that the migration from North America to South America occurred after the formation of the Isthmus of Panama. The species diversity in Mexico appears to reflect the habitat diversity within the temperate pine–oak forest zone. The presence of many conspecific diploid–polyploid clades in the phylogenetic tree reflects the high frequency of polyploidization among the perennial Stevia species.