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

Abstract

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.

A revision and morphological analysis of the Uruguayan species of Stevia (Compositae, Eupatorieae)

“…We proposed S. oxylaena to be a synonym of S. veronicae because the latter is more frequently used in literature (e.g., Orth Ritter et al 2010;Magalhaes et al 2013;Soejima et al 2017). Three specimens in total, kept at G and P that match the protologue of S. veronicae were found.…”

“…Currently, there is no agreement for recognizing these infrageneric categories , although some of them have been used for a comprehensive approach to the Brazilian species (Monteiro 1982;Nakajima 1991). In addition, molecular phylogenetic evidence indicated that these categories are not monophyletic (Soejima et al 2017).…”

Neuroendocrine and Metabolic Effects of Low-Calorie and Non-Calorie Sweeteners

“…Energy from fermentation of steviol glycosides (usually assessed as 2 kcal/g) is low (92). Stevia has a strong sweetening power, 200-to 400-fold higher than that of sucrose (94). Its maximal recommended daily intake is 4 mg/kg, and it is considered unsafe at higher doses (EU regulation 1129/2011) (95).…”

Relationships of Conoclinium, a Recently Diverged Genus (Asteraceae, Eupatorieae) and Description of a New Species from Western Mexico.

“…Similarly, there have been few studies that attempt detailed phylogenetic analysis of genera newly segregated from Eupatorium. Recent phylogenetic studies have focused on long-accepted genera, such as Stevia (Soejima et al, 2017) or Brickellia (Schilling et al, 2015), or have taken a broader synthetic approach sampling across multiple genera of the tribe Eupatorieae (Tippery et al, 2012;Rivera et al, 2016). Given the large size of the tribe and its widespread geographic distribution within the New World, studies of genera segregated from Eupatorium hold promise to reveal new insights that would have applications beyond the simple understanding of the systematics of the tribe.…”