Dung beetle assemblages organization in two contrasted areas of the Mediterranean region: affinities and divergences

Quantification of the species richness and diversity is important when comparing sites; these variables are influenced by local and regional factors. The structure of assemblages of dung beetles as well as their species composition and diversity were compared between two sites on both sides of the Mediterranean Sea (France FR and Tunisia TN). From a total of 132 traps, 15,778 specimens were collected belonging to 86 species (46 in FR vs. 40 in TN). Species composition varied highly between FR and TN (only 10 species in common). The temporal occurrence of Aphodiidae and Scarabaeidae showed different patterns due to several factors: phenology of species, geographical distribution and local ecological requirements. When quantifying the beta diversity, the turnover of species was for almost cases higher within the same season than between seasons. Moreover, seasonal turnover was different at both sites. Evenness and rank-abundance analyses demonstrated that autumn-winter was the most constraining season in FR, with one dominant species (Agrilinus constans) in winter assemblages (96.8% of individuals). Conversely summer was the most constraining season in TN, with Onthophagus taurus as dominant species in assemblages (87.7%). The influence of local and historical factors is discussed.