Eastern expansions of itinerant olive (Olea europaea)

Mapping a new direction for the origin and distribution of olive (Olea europaea), Mousavi et al. measure genetic diversity levels and population genetic structure of a representative set of Iranian ecotypes and varieties of olives screened by chloroplast and nuclear markers. The results of this analysis are coupled with archaeo-botanical and historical data, tracing a new scenario regarding the origin and distribution of this important fruit crop.

Geographical distribution of different gene pools detected through Mediterranean and Iran using Structure software
(A) Geographical distribution of different gene pools detected through Mediterranean and Iran using Structure software. Size of circles refers to the number of samples. (B) Four populations detected based on the entire set of samples. Red: Western Mediterranean (WM) cultivars including Morocco, Spain and Portugal; blue: Central-Eastern Mediterranean (CEM) cultivars including Algeria, Tunisia, France, Italy, Croatia, Albania, Greece, Turkey, Egypt, Cyprus, Lebanon and Syria; dark and light green: Iranian cultivars and ecotypes (IR). (C) Iranian samples split into four populations (1–4).

Approximate Bayesian Computation was applied to define the demographic history of olives including Iranian germplasm, and species distribution modelling was performed in order to understand the impact of the Late Quaternary Period on olive distribution. Two routes of olive differentiation are proposed: one westward, spreading along the Mediterranean basin, and another moving towards the East, reaching the Iranian plateau before its domestication.

Reference

Mousavi, S., Mariotti, R., Bagnoli, F., Costantini, L., Cultrera, N. G. M., Arzani, K., … Baldoni, L. (2017). The eastern part of the Fertile Crescent concealed an unexpected route of olive (Olea europaea L.) differentiation. Annals of Botany, 119(8), 1305–1318. https://doi.org/10.1093/aob/mcx027