Background: Hybridization events are relatively common in vascular plants. However, the frequency of these events is unevenly distributed across the plant phylogeny. Plant families in which individual species are pollinated by specific pollinator species are predicted to be less prone to hybridization than other families. However, exceptions may occur within these families, when pollinators shift host-plant species. Indeed, host shifts are expected to increase the rate of hybridization events. Pollinators of Ficus section Galoglychia are suspected to have changed host repeatedly, based on several cases of incongruence between plant phylogeny and taxonomy, and insect phylogeny and taxonomy. We tracked cyto-nuclear discordance across section Galoglychia as evidence for hybridization. To achieve a proper global view, we first clarified the monophyly of section Galoglychia as it had been questioned by recent phylogenetic studies. Moreover, we investigated if fig size could be a factor facilitating host shifts.

Patterns of mitochondrial DNA (mtDNA) variation revealed by RFLP were investigated for 63 individuals of the common fig, Ficus carica L., in 15 supposedly natural populations throughout the Mediterranean basin. Fifteen haplotypes were detected using one restriction enzyme (HindIII) and four probes (atp, coxIII, nad3rpsl2 and rps12). Mitochondrial diversity within populations varied from monomorphic to entirely polymorphic and population differentiation was high (F ST ¼ 0.323, P < 10 À5 ). Seven groups of populations were defined on the basis of genetic and geographic proximity and lead to significant pairwise F ST estimates except for the Corsican group which was similar to the Moroccan one. Fig populations were structured into three clusters: Balearic, West and East Mediterranean gene pools. The low diversity and strong differentiation of the Balearic populations strongly supports an ancient origin and the presence of natural populations in this area before domestication. Significant genetic differentiation between the West and East Mediterranean probably also reflects a diversification of the common fig over the Mediterranean basin preceding domestication. In contrast, Italian island populations seem to result from introduced cultivated fig since they present continental haplotypes. Our study represents a first mtDNA polymorphism survey and these indications should be confirmed by analysing local cultivated forms from the Baleares and from Italian islands and further natural populations from the East Mediterranean.

A detailed genomic linkage map of the olive [Olea europaea L. ssp. europaea (2x = 2n = 46)] was constructed with a 147 F1 full-sib ‘Olivière’ × ‘Arbequina’ progeny in a two-way pseudo-test cross-mapping configuration. Based on a logarithm of odds threshold of 6 and a maximum recombination fraction of 0.4, maternal and paternal maps were constructed using 222 makers [178 amplified fragment length polymorphism (AFLP), 37 simple sequence repeat (SSR), seven intersimple sequence repeat (ISSR)] and 219 markers (174 AFLP, 39 SSR, 6 ISSR) markers, respectively. The female map regrouped 36 linkage groups (LGs) defining 2210.2 cM of total map length with an average marker spacing 11.2 cM and a maximum gap of 48.5 cM between adjacent markers. The male map contained 31 LGs and covered a distance of 1966.2 cM with an average and a maximum distance between two adjacent markers of 10.3 and 40.4 cM, respectively. Mean LG size was 61.3 and 63.4 cM in the maternal and paternal maps, respectively. The LGs consisted of two to 17 loci (up to 21 loci in the paternal map) and ranged in length from 2.7 to 182 cM (female map) or from 4.1 to 218.1 cM (paternal map). Markers were distributed throughout the maps without any clustering. The total length of the consensus map was 3823.2 cM containing 436 markers distributed into 42 LGs with a mean distance between two adjacent loci of 8.7 cM. Both parental maps and the consensus maps were compared with previously published olive maps. Although not saturated yet, the present maps offer a promising tool for quantitative trait loci mapping because phenotypic characterization of the cross is currently carried out.