Post-Miocene tectonics of the Northern Calcareous Alps.

The Late Cretaceous orogeny followed by the Eocene collision of the Adriatic with the European plate dissected the Northern Calcareous Alps (NCA) by a number of well-studied strike-slip fault systems accommodating N-S shortening and E-W stretching. However, the post-Miocene fault activity is poorly constrained due to lack of Neogene faulted sediments, and glacial erosion of geomorphic indicators. Using the protected environment of caves, we fill the knowledge gap in the post-Miocene evolution of the NCA by paleostress analysis of 172 reactivated faults that offset passages in 28 caves near major faults. Constrained maximum age of caves, our results indicate that the NCA have been subjected to N to NE trending compression since Pliocene. Faulted speleothems dated with 230Th/U method, indicate that the recorded present-day stress state did not significantly change during the last 0.5 Ma. In contrast to the previously proposed post-Miocene N-S extension of NCA, but in agreement with what was observed in Vienna and Pannonian basins, we conclude that the eastward extrusion resulting from N-S convergence has continued despite a distinct slowdown of plate tectonic velocities in the late Miocene. The N-S extension affected only the Alpine front during Pliocene Molasse basin inversion, while at the scale of the Alpine orogen the NCA underwent successive N-S shortening and E-W stretching.

Investigating gene flow between the blind cavefish Garra barreimiae and its conspecific surface populations.

Cave-dwelling taxa often share the same phenotypic modifications like absence of eyes and pigmentation. These "troglomorphic characters" are expressed in the populations of Garra barreimiae from the Al Hoota Cave and nearby Hoti Pit in Northern Oman. Surface morphotypes of this cyprinid species are common throughout the distribution area. Very rarely individuals with intermediate phenotypes can be found. In the present study, potential gene flow between cave and surface populations was tested and population structure within five sampling sites was assessed. Overall, 213 individuals were genotyped at 18 microsatellite loci. We found that the cave populations have lower genetic diversity and are clearly isolated from the surface populations, which seem to be sporadically in contact with each other. The results indicate a recent genetic bottleneck in the cave populations. Thus, it can be assumed that during climatic changes the connection between cave and surface water bodies was disjoined, leaving a subpopulation trapped inside. Nevertheless, occasional gene flow between the morphotypes is detectable, but hybridisation seems only possible in cave habitat with permanent connection to surface water. Individuals from surface sites bearing intermediate phenotypes but cave genotypes imply that phenotypic plasticity might play a role in the development of the phenotype.