Geographical patterns of genetic variation in rosemary ( R osmarinus officinalis ) in the M editerranean basin

Climate changes during the Q uaternary had important effects on the evolution of E uropean plant species. The distribution of genetic variability in rosemary, a strictly M editerranean species of reputed P lio‐ Q uaternary origin for which the diversification centre is hypothesized to be located in the western part of the M editerranean basin, was investigated across the species range by using plastid microsatellites [plastid simple sequence repeat (cp SSR )] markers. Seven out of the 17 primer pairs screened were polymorphic, with up to four alleles, yielding a total of 17 size variants combined into ten haplotypes. A permutation test to investigate for geographical structure showed no significant differences between R ST and G ST , indicating that the species lacks geographical structure. Low correlation between genetic and geographical distances was shown by the M antel test. B ayesian analysis identified two coancestry groups of populations. The distribution of genetic diversity supports the hypothesized origin in the western M editerranean basin, and with the demographic expansion test indicates three different routes of migration: a northern route expanding along the northern side of the M editerranean and two southern routes, one from west to east through N orth A frica and reaching C yrenaica, and a second to the south‐west of the I berian P eninsula, from where it came back to the south–central areas. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society , 2013 , 171 , 700 – 712 .