canigou_petitEarth climate is changing at a global scale as a result of human activity. Such changes have tremendous consequences for human societies by increasing natural catastrophes and by causing profound modifications on ecosystems that are essential for human survival. From a biological conservation standpoint, global climate change has come to accelerate the rate of destruction of biodiversity. An extremely dynamic geological history and climatic oscillations caused by earth’s movement across the solar system have shaped Mediterranean ecosystems and have converted this region in one of the planetary hot-spots of biodiversity. Unfortunately, overpopulation and a long-history of human occupation have had a deep impact on Mediterranean biological communities and have brought many endemics to the verge of extinction. The study of the past effect of climatic changes on the Mediterranean biota, namely the Pleistocene ice-ages, may shade light on the future impact of global warming on current ecosystems and can help to predict the sensitivity of particular areas to such changes. Modern molecular techniques are powerful tools for the study of the factors that shaped species relationships and population structure and provide the temporal framework for the occurrence of evolutionary events. The ground spider genera Harpactocrates and Parachtes provide an excellent model for the study of the effect of past climatic changes on the origin and shaping of biodiversity in the Western Mediterranean. They are both endemic to the region, and their species have high-elevation, non-overlapping distributions across major cordilleras in the Iberian and Italian Peninsulas, the Alps and the larger Islands of the region. We suggest that the diversity and distribution ranges of these genera are mostly the result of Pleistocene climatic oscillations and post-Oligocene tectonic movements. We propose to study these spider genera to identify the factors that promoted their diversification and to generate a precise temporal framework for the occurrence of such events. The results of this research will have important implications for the understanding of the origins of our biodiversity and for its conservation. Moreover, we will provide the scientific community with information to calibrate molecular clocks for studies in spiders or the Mediterranean region