We found two potential crossings in the Adige Valley, likely the biggest constraint for the study population to expand eastward and impeding dispersal to/from the closest bear population (Dinaric Pindos population).
We expect a higher level of genetic structure (i.e. higher Fst values) for all species in the fragmented landscape because weirs might partially impede dispersal between patches (Raeymaekers et al. 2008).
This suggests that a barrier between Málaga and the Guadalquivir River may prevent population mixing and led to vicariant diversification by impeding dispersal, from the betic uplift in the late Miocene/early Pliocene until the present.
Eastward gene flow could be impeded by dispersal barriers (e.g. currents), or by selection (i.e. unfavourable environmental conditions) causing outbreeding depression if lineages are locally adapted.
Physical barriers, such as rivers and roads, constrain the movement of animals, usually by preventing access to adjacent habitats and impeding dispersal.
On the other hand, barriers degrade preferred habitat and impede dispersal, contributing to the degree of genetic differentiation among populations.
In contrast, barriers both fragment and degrade preferred habitat and impede dispersal, contributing to the genetic differentiation of populations.
Lack of isolation by distance observed here suggests that there are no physical barriers impeding broad dispersal.
In the case of marine organisms, extrinsic factors such as light, temperature, pH and of course currents may promote or impede larval dispersal.
The removal of dispersing larvae from axial troughs by these currents and the apparent scarcity of vent habitats may together impede the dispersal of some species.
