HIGH ALTITUDE ENDEMIC CARABID BEETLES AS BIOGEOGRAPHIC INDICATORS: A CASE STUDY IN EQUATORIAL ANDES

The tropical Andean páramo ecosystem emerged after the final uplift of the Cordilleras, leading to the rapid radiation of species-rich clades and to the diversification of narrowrange endemic taxa in isolated high-altitude island-like environments. This study focuses on the wingless carabid species that inhabit the so-called superpáramo, i.e. the upper belt of this ecosystem, above 4200/4300 m a.s.l. The low dispersal ability of these cold-adapted ground beetles gives the opportunity of an exceptionally fine-grained analysis of endemism patterns. Two hypotheses are tested: (i) that most of these endemic carabids have evolved by niche shift, from local ancestors in the montane forest, rather than by long range dispersal from cool regions north or south, and (ii) that the high level of microendemism observed in several genera is the result of recent speciation events, related to the volcanic and tectonic history of the Andes.