Plastid and nuclear DNA polymorphism reveals historical processes of isolation and reticulation in the olive tree complex (Olea europaea)

摘要: Aim The olive tree is considered one of the best indicators Mediterranean climate. species’ distribution associated with geographical and bioclimatic factors, as well being influenced by a long period cultivation. Despite concerted efforts different research groups, origin still remains elusive. In present study, relationships between taxa populations covering entire range Olea europaea were investigated using both maternal (plastid genome) biparental (nuclear markers to disclose evolutionary patterns in complex. Phylogenetic phylogeographical results two-genome analyses interpreted biogeographical context. Location Mediterranean, temperate subtropical floristic regions Old World. Methods Phylogeographical reconstructions plastid DNA polymorphism performed microsatellites, restriction sites indels on wide sample 185 representative trees across World, including 28 herbarium specimens from remote areas. Additionally, potential utility ITS-1 pseudogene for phylogenetic was explored Bayesian maximum parsimony approaches subsample 38 trees. Results Forty haplotypes recognized split into two lineages seven sublineages. analysis sequences also allowed identification differentiated groups. Distribution ribosomal congruent, but particular cases incongruence disclosed (particularly Sahara Madeira). Lastly, divergent copies isolated same four individuals subspecies. Main conclusions congruence suggested an scenario predominant isolation during PlioPleistocene Macaronesia, southern Africa, eastern Africa Asia. Saharan desert appeared have played important role vicariant barrier northern African early times. Incongruence some nuclear results, intermingled single individuals, result recurrent reticulation events We identified ancient hybrid zone north-eastern mountains, where co-exist. this paper, previous studies, suggest that cultivated originated pre-Quaternary ancestor, no evidence recent origin. contrast, continuous process domestication through local hybridization natural may brought about remarkably high genomic diversity among Mediterranean.