The Haynei is one of seven species aggregates (clusters of species having similar flower morphology) recognized in section Oncocyclus of genus Iris. This aggregate, characterized by dark-colored flowers, is represented by six species in Israel and adjacent Jordan. There is, however, no knowledge of the genetic relationship of these species making verification of their taxonomic status impossible. We investigated genetic variation in this group using analysis of whole chloroplast genomes and amplified fragment length polymorphism (AFLP). We also used species distribution modeling (SDM) to predict species ranges under current climatic conditions. We found some population groups within the currently recognized species of section Oncocyclus to represent dramatically different genetic entities which devaluates a general trend of merging many previously recognized species of section Oncocyclus based on their flower morphology. Despite the importance of homoploid hybridization in this group’s evolution and some apparently sporadically happening inter-specific gene flow, the main evolutionary forces in Oncocyclus appear to be vicariance and spatial isolation. Our findings suggest that some of the currently recognized species in section Oncocyclus need revision. A revision must be based on genetic analyses allowing the reconstruction of ancestry and recognition of the importance of vicariance and spatial isolation in the evolution of this group. The implications of the present findings for conservation are discussed.
Historical processes during the Quaternary are likely to have left a signature on the geographical distribution of intraspecific genetic variation. In particular, high genetic uniqueness could be expected within glacial refugia for multiple species. We aimed to test this for plants in China and whether multi-species hotspots of genetic diversity are good indicators of glacial refugia in this region. From chloroplast DNA haplotype data for 116 species we calculated two local genetic diversity metrics for each species: haplotype genetic richness and genetic uniqueness. From these two, only uniqueness could reliably identify refugia, whereas richness may indicate either glacial refugia or areas recolonized by genetic lineages from different refugia in the postglacial period. Our results suggest the occurrence of numerous cryptic refugia and their likely importance in the maintenance and evolution of the Chinese flora, and indicate that an approach that locates geographic hotspots of genetic diversity data can reliably identify refugia.
In reconstructing taxon evolution, historical biogeography is concerned with two kinds of speciation events, both resulting in a fragmented taxon distribution – vicariance and dispersal. We used PCR-RFLP of plastid DNA and a ribosomal internal transcribed spacer, sequencing of the rps16-trnK chloroplast region, flow cytometry (florescence-activated cell sorter; FACS), and ecological niche modeling to understand the role of these two processes in a disjunct distribution of genus Mandragora. The observed phylogeographic structure only partly coincided with currently recognized species. Commonly used recognition of a single species in the whole Mediterranean is not supported, given that a single haplotype observed from Morocco and Spain to Turkey is strikingly different from the haplotypes found in Israel. In the Sino-Himalayan area, the previously recognized M. chinghaiensis is nested within the M. caulescens clade indicating a very recent diversification within this lineage. And, most importantly, the obtained minimum spanning tree, observed haplotype distribution, and results of FACS call into question the existence of M. turkomanica as a species, and even as a lower taxonomic unit. Rather, the mandrake from Central Asia is nested within those from Israel, suggesting their closely related evolutionary history and ancient human assisted migration from Israel to Persia in historic times. Our study suggests that human assisted migration can explain the cases of disjunct species distribution for which vicariance was previously considered as the only plausible explanation.