Biogeography of the xerophytic genus Anabasis L. (Chenopodiaceae)

Abstract

Aim Using the extremophile genus Anabasis, which includes c. 28 succulent, xerophytic C4 species, and is widely distributed in arid regions of Northern Africa, Arabia, and Asia, we investigate biogeographical relationships between the Irano‐Turanian floristic region (ITfr) and its neighboring regions. We test whether the spread of arid and semi‐arid biomes in Eurasia coincides with the biogeography of this drought‐adapted genus, and whether the ITfr acted as source area of floristic elements for adjacent regions. Location Deserts and semi‐deserts of Northern Africa, Mediterranean, Arabia, West and Central Asia. Methods Four cpDNA markers (rpL16 intron, atpB‐rbcL, trnQ‐rps16, and ndhF‐rpL32 spacers) were sequenced for 58 accessions representing 21 Anabasis species. Phylogenetic relationships and divergence times were inferred using maximum likelihood and a time‐calibrated Bayesian approach. To document the extant distribution of Anabasis, material from 23 herbaria was surveyed resulting in 441 well‐documented collections used for the coding of eight floristic regions. Using this coded data, ancestral range was estimated using “BioGeoBEARS” under the DEC model. Results Anabasis originated during the Late Miocene and the ancestral range was probably widespread and disjunct between Western Mediterranean and the Irano‐Turanian regions. Diversification started with two divergence events at the Miocene/Pliocene boundary (5.1 and 4.5 mya) leading to Asian clade I with ITfr origin which is sister to a slightly younger Asian clade II, which originated in the Western ITfr, and a Mediterranean/North African clade with an origin in the Western Mediterranean. Main conclusions Anabasis did not follow aridification and continuously expanded its distribution area, in fact its probably wide ancestral distribution area seems to have been fragmented during the very Late Miocene and the remnant lineages then expanded into neighboring arid regions. This genus supports the role of the ITfr as source area for xerophytic elements in the Mediterranean and Central Asia.

Pleistocene dynamics of the Eurasian steppe as a driving force of evolution: Phylogenetic history of the genus Capsella (Brassicaceae)

“…The "southern route” scenario: Mediterranean steppes are thought to be descendants of the Anatolian steppes that expanded throughout the Mediterranean during the Pliocene (Suc et al., 2018 ). This route, however, is discussed for xeric steppe elements only (Jia & Bartish, 2018 ; Lauterbach et al., 2019 ; Manafzadeh et al., 2014 ; Žerdoner Čalasan et al., 2021 ), and Capsella does not belong to this ecological group. The main argument against an Early Pliocene southern Capsella route is the estimated divergence time between the two basally branching lineages, the Mediterranean C. grandiflora/rubella and the continental C. orientalis lineage of ca.…”

Cenozoic evolution of the steppe-desert biome in Central Asia

“…1 ) in particular serving as a center for plant diversification since at least the early Miocene [e.g., ( 3 , 117 )]. Molecular phylogenetic analyses reveal that diversification in both the alpine biome [e.g., ( 3 , 118 )] and steppe-desert lowlands ( 119 – 121 ) occurred during the mid- to late Miocene, which appear to be driven mainly by cooling and progressive aridity, respectively. This may be related to the generalized northward expansion of the Tibetan Highland and mountain ranges in the vicinity, including uplift of the Tian Shan, Pamir, Kunlun, and Qilian Shan-Nan Shan ( 122 , 123 ).…”

Phylogeny and biogeography of the northern temperate genus Dracocephalum s.l. (Lamiaceae)

“…As has been discussed above, the genus might have experienced an early rapid radiation during the middle to late Miocene, as major lineages of the genus arose in a short timescale between 11 and 7 Ma, which is consistent with the origin and diversification of other taxa distributed in the Asian interior arid‐zone flora such as Ephedra L. (Ephedraceae; Qin et al., 2013), Caragana Fabr. (Fabaceae; Zhang et al., 2016), Astragalus L. (Fabaceae; Azani et al., 2019), and Anabasis L. (Amaranthaceae; Lauterbach et al., 2019). Pollen records also demonstrated that herbs first become widespread in Central Asia at ca.…”