Biogeography of the Azorean Coleoptera

Borges, Paulo A. V.

http://hdl.handle.net/10400.3/1906

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Authors

Borges, Paulo A. V.

Abstract(s)

After 140 years of study, the Azorean beetle fauna is, in some islands, still poorly known, with 51 families. 305 genera, and 524 species present in the whole archipelago (61 of which - 11.6% - seem to be endemic). The intention of this account was to investigate which factors could best predict the number of species from each Azorean island. The correlations between the known distribution of the Azorean Coleoptera per island (total species, autochthonous species, total of endemics, exclusive endemics), and the area distance from mainland altitude and geological age were computed. We found that there were good correlations between the species diversity and the geological age of the islands, most remarkable being the value of r=0,83 (p<0,005) for the exclusive endemics. Considering only the autochthonous species we will find an interesting Mediterranean-Macaronesian component with the endemics reaching 29%. This Mediterranean-Macaronesian component reaches 31.4% of the autochthonous species: moreover, there is a close taxonomic relation between many Azorean neo-endemics and related Madeiran and Canarian species. These two facts can signify colonization with Macaronesian origin by "stepping stones". Apparently the poverty of the Azorean Coleoptera is somewhat illusory, because the differences in diversity between the Azores and other Macaronesian archipelagoes may be explained in two probable order of importance by: isolation, geological youth lack of strong diversity in some ecological parameters and an unsuitably humid climate. The disastrous action of me Pleistocene glaciations though difficult to prove could be alternative or complementary to the other factors.