An investigation by the Spanish Scientifc Council (Consejo Superior de Investigaciones Cientficas, CSIC) reveals that the large impacts occurred during the last ice age maintain their effects on the current distribution of dung beetles of the scarab family (Scarabaeidae). The presence of these beetles in Europe seems to be more influenced by the climate of that glaciation than by the present one.
The study, published yesterday in the journal Ecology Letters, analyzed the species richness and the structure of their communities throughout the different regions of the European territory from the Ural Mountains to the Iberian Peninsula. The selection of this family of insects was motivated by their high dispersal ability and because their food sources (mainly cattle and sheep dung) are present throughout the continent.
Scarabs are insects of tropical origin that cannot survive below 0 C mean annual temperature, "so it could be expected that their presence gradually decreases as temperatures drop down northwards " says the researcher from the National Museum of Natural Sciences, CSIC, Joaqun Hortal. However, the analysis of the relationship between the magnitude of climate change since the last glaciation and the distribution of scarabs evidences that these insects are not evenly distributed according to this gradient, but rather show two different patterns, one in the north and one in the south. Horton said: "The border defining the two areas is almost similar to the limit of 0 C of mean annual temperature at the time of the last ice age."
Although scarab species richness is actually lower in the north that in the south, two other characteristics can be explained under the hypothesis of the influence of the last ice age.
The first one is based on the species present throughout Europe. Data show that all scarab species living in the northern territory above the border defined by the 0 C limit in the last glaciations are
|Contact: J. Hortal|