Intrinsic and extrinsic factors act at different spatial and temporal scales to shape population structure, distribution and speciation in Italian Barbus (Osteichthyes: Cyprinidae)

Previous studies have given substantial attention to external factors that affect the distribution and diversification of freshwater fish in Europe and North America, in particular Pleistocene and Holocene glacial cycles. In the present paper we examine sequence variation at one mitochondrial and four nuclear loci (over 3 kbp) from populations sampled across several drainages of all species of Barbus known to inhabit Italian freshwaters (introduced B. barbus and native B. balcanicus, B. caninus, B. plebejus and B. tyberinus). By comparing species with distinct ecological preferences (rheophilic and fluvio-lacustrine) and using a fossil-calibrated phylogeny we gained considerable insight about the intrinsic and extrinsic processes shaping barbel distribution, population structure and speciation. We found that timescales of Italian barbel diversification are older than previously thought, starting in the Early Miocene, and involving local and regional tectonism and basin paleo-evolution r...