Format: ORAL

Emmanuele Farris1, Jordi Lpez-Pujol2, Alfredo Maccioni1, Guillaume Papuga3, Virginie Pons4, Alfonso Susanna2, John D. Thompson4, Roser Vilatersana2

1 University of Sassari, Sassari, Italy; 2 Institut Botanic de Barcelona (IBB, CSIC-CMCNB), Barcelona, Spain; 3 University of Montpellier, Montpellier, France; 4 Centre d’Ecologie Fonctionnelle et Evolutive-CNRS, Montpellier, France

Homoploid hybridisation gives rise to new lineages having the same chromosome numbers as parental species. Therefore the reproductive isolation of hybrid individuals from parental ones is complex and slow. Moreover, homoploid hybrids act as a bridge between the two parental species, favoring introgression events among them. These often combined processes form hybrid zones where homoploid hybrid populations and introgressed parental populations coexist. This is the case for the western Mediterranean Cyclamen subgenus Psilanthum, composed of two closely related allopatric taxa (Cyclamen repandum and C. balearicum). Cyclamen repandum is a geographically widespread taxon (central Mediterranean Basin), whereas the second is endemic to the Balearic Islands and the south of France west of the Rhne valley. In 2002, three small populations of C. balearicum, C. repandum and bicoloured flowers were discovered in northern Corsica. These populations grow on limestone outcrops in a disjunct, until then unknown, peripheral part of the distribution of the endemic species and in an ecologically marginal area for the widespread species. Further, based on floral traits and genetic variability, it was highlighted that bicoloured floral types in these populations were of homoploid hybrid origin. Later a wide hybrid zone was discovered in north-western Sardinia, where bicoloured floral types dominate in hybrid populations, revealing a more advanced hybridisation process compared to Corsican populations. Recent findings showed that the cpDNA of all floral types in Sardinian populations is of C. balearicum rather than C. repandum, highlighting a bi-directional asymmetric introgression. These findings emphasise the need for precise comprehension of ongoing hybridisation processes to plan appropriate conservation strategies. These should include both small areas with incipient hybridisation events (like in Corsica) and wide hybrid zones where reticulate introgression among parental and hybrid lineages is the prevailing process on wide spatial scales (like in Sardinia).