Phylogenetic Placement and Phylogeography of Large-Flowered Lotus Species (Leguminosae) Formerly Classified in Dorycnium: Evidence of Pre-Pleistocene Differentiation of Western and Eastern Intraspecific Groups

Abstract

The Mediterranean region is a center of species and genetic diversity of many plant groups, which served as a source of recolonization of temperate regions of Eurasia in Holocene. We investigate the evolutionary history of species currently classified in Lotus sect. Bonjeanea in the context of the evolution of the genus Lotus as a whole, using phylogenetic, phylogeographic and dating analyses. Of three species of the section, L. rectus and L. hirsutus have wide Mediterranean distribution while L. strictus has a disjunctive range in Bulgaria, Turkey, Armenia, Eastern Kazakhstan, and adjacent parts of Russia and China. We used entire nuclear ribosomal ITS1-5.8S-ITS2 region (nrITS) and a plastid dataset (rps16 and trnL-F) to reconstruct phylogenetic relationships within Lotus with an extended representation of Bonjeanea group. We analyzed the phylogeographic patterns within each species based on the plastid dataset. For divergence time estimation, the nrITS dataset was analyzed. Our results confirmed the non-monophyletic nature of the section Bonjeanea. They indicate that Lotus is likely to have diverged about 15.87 (9.99–19.81) million years ago (Ma), which is much older than an earlier estimate of ca. 5.54 Ma. Estimated divergence ages within L. strictus, L. rectus, and L. hisrutus (6.1, 4.94, and 4.16 Ma, respectively) well predate the onset of the current type of Mediterranean climate. Our data suggest that relatively ancient geological events and/or climatic changes apparently played roles in early diversification of Lotus and its major clades, as well as in formation of phylogeographic patterns, in at least some species.

Mediterranean Subspecies versus Californian Varieties: An Example from Acmispon (Leguminosae, Loteae)

“…Alternatively, the apparent difference may be mainly caused by the differences in taxonomic approaches adopted by botanists at the two sides of the Atlantic. Resolving the question will be facilitated by a more consistent use of criteria for recognizing infraspecific taxa, direct comparisons of levels of infraspecific variation using statistical approaches, dating more detailed molecular phylogenetic trees (e.g., [47,48]), and comparing ratios of species with recognized subspecies or varieties in different geographical regions across large data sets that include various taxonomic groups. The recently published worldwide checklist of legumes [49] provides an opportunity of making such comparisons.…”

When Morphology and Biogeography Approximate Nuclear ITS but Conflict with Plastid Phylogeny: Phylogeography of the Lotus dorycnium Species Complex (Leguminosae)

“…was traditionally accepted as a distinct genus by European botanists [ 1 , 2 ], but on the global scale it cannot be properly separated from Lotus in terms of morphology [ 3 , 4 , 5 , 6 ]. Molecular phylogenetic data showed that even at the European scale separation of Dorycnium is strongly problematic [ 7 , 8 ]. In a monograph of Dorycnium which was published 120 years ago but which still remains the latest detailed worldwide study of the group, Rikli [ 9 ] recognized three sections within the genus: Canaria Rikli, Bonjeanea Taubert, and Eudorycnium Boiss.…”

“…(the valid name of the latter section is Dorycnium ). Members of the sections Canaria and Bonjeanea combine morphological characters of the genera Lotus and Dorycnium in their traditional circumscriptions [ 8 ]. In the present paper, we follow a wide concept of the genus Lotus , which includes all members traditionally classified in sections Canaria , Bonjeanea , and Dorycnium .…”

“…In the present paper, we follow a wide concept of the genus Lotus , which includes all members traditionally classified in sections Canaria , Bonjeanea , and Dorycnium . The section Canaria is not closely related to members of the other two sections [ 7 , 8 , 10 ]. This agrees with earlier ideas of Gillett [ 4 ].…”

A Multivariate Morphometric Analysis of the Genus Lotus L., 1753 (Fabaceae, Loteae) From Egypt

“…The greatest genetic diversity for Lotus occurs in the Mediterranean Basin (Grant, 1991;Sokoloff, 1998). Based on previous studies, this genus is a taxonomically difficult genus as it includes complexes of closely related groups with similar vegetative characters (Gillett, 1958;Heyn, 1967;Kramina, 1999Kramina, , 2006Kramina and Sokoloff, 2004;Kramina et al, 2016Kramina et al, , 2018Kramina et al, , 2020Kramina et al, , 2021, including seasonal polymorphisms (Heyn, 1970), and it is difficult to distinguish among the species (Ojeda et al, 2009).…”