Phylogeny, biogeography and divergence times of Astragalus section Incani DC. (Fabaceae) inferred from nrDNA ITS and plastid rpl32‐trnL_(UAG) sequences

Abstract

Astragalus sect. Incani, one of the most species‐rich sections of Astragalus with ca 140 species, is well known for its taxonomic complexity resulting from overlapping morphological characters and high phenotypic plasticity. Its main centers of diversity are in Iran and Turkey with about 120 species. Using nrDNA ITS and plastid rpl32‐trnL(UAG) markers, we reconstructed the phylogeny of members of the section by means of maximum parsimony, maximum likelihood, Bayesian, Beast and S‐DIVA analyses. This is the first comprehensive work on the section Incani covering its full geographic range. All members of the section (including A. subsecundus) except A. platyphyllus formed a well‐supported clade (Incani s.s.). Within the section, two major groups with different geographic distribution were detected. One group includes nine examined species restricted to eastern Iran and Central Asia and the other group comprises a majority of the species from west and northwestern Iran, Turkey and southern Europe. The Divergence time analysis suggests that Incani s.s. originated in the late Pliocene and a majority of the speciation events dates to the last 1–1.5 Myr. This indicates that the recent diversification of Incani s.s. coincided with climatic changes during the Pliocene and Pleistocene and was followed by complex biogeographical processes in which dispersal have been vital for shaping the current distribution pattern . The S‐DIVA suggested a predominantly east–west route of dispersal from an origin in the east, and a major phylogenetic split between eastern and western lineages. However, the geographical distribution of A. monspessulanus/A. incanus and A. ackerbergensis/A. gueldenstaedtiae does not correspond to their phylogenetic positions. The former species are restricted to southern Europe/North Africa, but belong in two distinct subclades. The latter, restricted to northeastern Iran are phylogenetically close to species of western and northwestern Iran and Turkey. Astragalus sykesiae is resurrected as a distinct species separated from a broadly defined A. mercklinii.

Anatomy of a mega-radiation: Biogeography and niche evolution inAstragalus

“…Astragalus has used few genetic loci and focused either on representative sampling (Wojciechowski et al, 1999;Scherson et al, 2008) or on more extensive sampling of focal clades (Scherson et al, 2008;Bartha et al, 2013;Azani et al, 2017bAzani et al, , 2019Bagheri et al, 2017;Amini et al, 2019) and areas (Su et al, 2021).…”

“…The ecological dominance, species richness, and narrow endemism of Astragalus in many semiarid areas of the Northern Hemisphere have attracted the attention of biogeographers and ecologists (Scherson et al, 2008;Samad et al, 2014;Hardion et al, 2016;Amini et al, 2019;Azani et al, 2019;Záveská et al, 2019;Plenk et al, 2020;Li et al, 2021;Wang et al, 2021;Maassoumi and Ashouri, 2022). Perhaps the major biogeographic finding of molecular phylogenetic studies in Astragalus, suspected previously on the basis of chromosome counts (Ledingham, 1960;Barneby, 1964), is the recovery of a clade comprising nearly all North American Astragalus, informally termed the Neo-Astragalus clade (Wojciechowski et al, 1993(Wojciechowski et al, , 1999, which renders species in the Eastern Hemisphere a paraphyletic group.…”

Anatomy of a mega‐radiation: Biogeography and niche evolution in Astragalus

“…Most previous phylogenetic work in Astragalus has used few genetic loci and focused either on representative sampling (Wojciechowski et al, 1999; Scherson et al, 2008) or on more extensive sampling of focal clades (Scherson et al, 2008; Bartha et al, 2013; Bagheri et al, 2017; Amini et al, 2019; Azani et al, 2017b, 2019) and areas (Su et al, 2021). Our analysis primarily corroborates previous phylogenetic findings across Astragalus while greatly improving sampling of Eurasian species.…”

“…The ecological dominance, species richness, and narrow endemism of Astragalus in many semi‐arid areas of the northern hemisphere and a smaller disjunct portion of the southern hemisphere have attracted the attention of biogeographers and ecologists (Scherson et al, 2008; Samad et al, 2014; Hardion et al, 2016; Amini et al, 2019; Azani et al, 2019; Záveská et al, 2019; Plenk et al, 2020; Li et al, 2021; Wang et al, 2021; Maassoumi and Ashouri, 2022). Perhaps the major biogeographic finding of molecular phylogenetic studies in Astragalus , suspected previously based on chromosome counts (Ledingham, 1960; Barneby, 1964), is the recovery of a clade comprising nearly all North American Astragalus , informally termed the Neo‐Astragalus clade (Wojciechowski et al, 1993, 1999), which renders species in the eastern hemisphere a paraphyletic group.…”

Palyno-morphology of Hedera L. (The ivy genus, araliaceae) and their systematics implications

“…Micromorphological characters are good diagnostic value to recognize many taxa, fundamentally at the species level. The pollen morphological analysis is successfully used as an additional document for delimitation of the taxa (AMINI et al, 2018;. In the Northwest European Pollen Flora mentioned that pollen class of Hedera is 3-zonocolporate, sub-erect to semi-erect with reticulate ornamentation (VAN HELVOORT and PUNT, 1984).…”