Evidence for reticulate palaeogeography: beetle diversity linked to connection-disjunction cycles of the Gibraltar strait

Aim Dispersal barriers between areas within some regions have appeared and disappeared throughout evolutionary time. Here we describe the distribution al patterns displayed by three taxa living in such kind of regions. These p atterns can be better explained considering a reticulated rather than a hie rarchically branched palaeogeography. Location Western Mediterranean. Methods The taxa studied are Misolampus (Coleoptera, Tenebrionidae), Tentyr ia (Coleoptera, Tenebrionidae) and Thorectes (Coleoptera, Geotrupidae). All them are flightless and show a high degree of endemicity. The individual p attern of area relationships was determined separately for each genus by Br ooks Parsimony Analysis (BPA). A theoretical general area cladogram was con structed based on the palaeogeographical history of the region. Finally, th e general area cladogram is reconciled with the individual ones. Results The ancestor of Misolampus probably was North African. Land dispers al toward the Iberian Peninsula is proposed. Speciation within Iberia is re lated to specific vicariance events, and the presence of insular (Balearic Islands) populations is explained by sea-surface or, more probably, human-m ediated dispersal. The ancestor of Tentyria was Iberic. The proposed hypoth esis to explain the current species distribution mainly relies on the occur rence of specific vicariance events. However, the occurrence of some sea-su rface dispersal event is not discarded. Almost all possible vicariance even ts can be recognized in the first clade of the Thorectes genus. There is ev idence for dispersal between Africa and Europe at different dates and in bo th directions. In spite of some uncertainties, the appearance of the second Thorectes clade can also be explained by the occurrence of specific histor ical events. An ancient dispersal toward the eastern Mediterranean and seve ral dispersal events during the Messinian seem likely. Main conclusions The same historical events have specific outcomes in every tree (even in every branch within a tree) depending on the ability for dis persal and speciation of each taxon. Connection-disjunction cycles of dispe rsal barriers have acted as diversity producers.