Tenebrionid beetle distributional patterns in Italy: multiple colonisation trajectories in a biogeographical crossroad

Abstract

Placed in the centre of the Mediterranean Basin, Italy is a complex biogeographical crossroad between North Western Europe, Central Europe, Eastern Europe and North Africa. The distribution of 280 species and subspecies of tenebrionid beetles in 17 Italian natural regions was used to study the influence of climatic, spatial and historical (palaeogeographical and palaeoecological) factors on current patterns of species richness, endemism and turnover (i.e. inter‐regional biogeographical differences). In accordance with the general latitudinal pattern of biodiversity in Europe, both tenebrionid richness and endemism increase southwards, in response to variations in rainfall and temperatures, as expected for thermo‐xerophilic animals. Turnover was correlated with both inter‐regional climatic dissimilarities and geographical distances. The importance of spatial relationships independent from climate, but consistent with palaeogeographical and palaeoecological history, was also confirmed by inter‐regional relationships based on all species and endemics only. Biogeographical similarities between Italian regions and adjacent European and North African source areas showed distinct geographical patterns which reflect various dispersal trajectories. During the Pleistocene glacials, cold adapted species coming from northern areas via the Alps used the Apennines as a filter to disperse into central and southern Italy, thereafter remaining confined to high altitude areas after deglaciation. Xero‐thermophilic species coming from North Africa or east Mediterranean countries colonised southern Italian regions probably in more ancient times. Islands and southern areas acted as centres of both speciation and post‐glacial recolonisation.

Higher level molecular phylogeny of darkling beetles (Coleoptera:Tenebrionidae)

“…They are also particularly diverse in tropical forests (Kaszab, ; Yeates et al , ; Matthews & Bouchard, ), with many groups having exclusive pantropical distributions (Matthews et al , ). Because of their worldwide distribution and their high level of diversity, they have become the focus of numerous studies in evolutionary biology (Papadopoulou et al , , ; Condamine et al , ; Lamb & Bond, ), island biogeography (Juan et al , , ,b; Rees et al , ), macroecology (De Los Santos et al , ; Carrara & Flores, ; Fattorini & Ulrich, ; Fattorini, ), developmental biology (Ohde et al , ) and conservation biology (Fattorini, , ; Cárdenas et al , ; Fattorini & Baselga, ). In addition, the numerous disjunct distribution patterns recovered in many tenebrionid groups (e.g.…”

Biogeography of western Mediterranean butterflies: combining turnover and nestedness components of faunal dissimilarity

“…The aim of our study was to compare the pattern of each partitioned and unpartitioned component of faunal dissimilarity, and to dissect local evidence of historical and ecological phenomena (endemicity, relictuality, filtering and peninsular effects) (e.g. Dobrovolski et al, 2012;Fattorini, 2013;Mouillot et al, 2013) using two approaches. The first approach focused on detecting faunal regionalization based on overall dissimilarity matrices.…”

Taxonomic variation in levels of endemism: a case study of Italian tenebrionid beetles

“…In Central Italy, the proportion of endemics increases with elevation; endemics tend to be more than 40% of the tenebrionids occurring over 1200 m a.s.l., 50% over 1800 m, and 100% over 2200 m (Fattorini, ; S. Fattorini & C. Mantoni, unpublished data). Mountains can be viewed as islands, and thus, the presence of endemics restricted to the Central Apennines can be a result of this form of geographical isolation (Fattorini, , ). Isolation is typically considered a factor promoting the evolution of flightlessness in insects (Roff, ), but also living under stones or barks may promote the loss of wings (Carpaneto & Fattorini, ).…”

“…Looking at the geographical distribution of endemic species in Italy (Fattorini, ), it appears that the areas with the highest proportions of endemics were the two main islands (Sardinia and Sicily) and the mountainous sectors of Central Italy (Apennines). In Central Italy, the proportion of endemics increases with elevation; endemics tend to be more than 40% of the tenebrionids occurring over 1200 m a.s.l., 50% over 1800 m, and 100% over 2200 m (Fattorini, ; S. Fattorini & C. Mantoni, unpublished data). Mountains can be viewed as islands, and thus, the presence of endemics restricted to the Central Apennines can be a result of this form of geographical isolation (Fattorini, , ).…”

“…The current taxonomic dividing line between species and subspecies, however, is arguably arbitrary as applied to tenebrionids. Thus, we considered species and subspecies as terminal taxonomic units of equal rank (see Fattorini, for details). For simplicity, both species and subspecies will be referred to as ‘species’.…”