Sequence variation and dispersal ability by epizoochory in Mediterranean Cynoglossum (Boraginaceae): preliminary evidence from ITS and fruit traits.

Cynoglossum comprises ca. 75 biennial to perennial (rarely annual) herbs in the Old and New World, mainly growing in open habitats and especially pasturelands. A major centre of diversity is the Mediterranean, where some 30 species range from Anatolia to the Iberian peninsula and north Africa. Taxonomists know that their identification is often difficult mainly due a weak phenotypic differentiation in vegetative and reproductive characters. Available karyological data also indicate highly conserved chromosome complements. This may be associated with a relatively recent radiation triggered by the onset and spread of nomadic and transhumant pasture in the Mediterranean pre-history, perhaps between 10.000 and 8.000 y.a. The role of migrating herds of sheep and other mammals as effective agents of long-distance dispersal in epizoochorous plant groups has been experimentally shown by various authors. Cynoglossum is one such groups, its fruits being provided with characteristical glochids that allow the immediate interlocking to the fur of wild and domesticated mammals, especially sheep and goats. We tested this hypothesis using a combined morphoanatomical and phylogenetic approach. The dispersal ability of the fruits was evaluated based on structural features examined using LM and SEM microscopy with EDX microanalysis; their attachment potential to sheep and cattle coat was estimated by means of the General Linear Models by Römermann et al. (in Oikos 110: 219-230, 2005). Nuclear DNA ITS sequences were then generated for nearly all Mediterranean species. These were used to open a window on the phylogeny of Cynoglossum and to evaluate the level of ITS variation as compared with that in other genera of Boraginaceae characterized by mainly non-epizoochorous strategies of seed dispersal.