A biogeographical analysis of the tenebrionid beetles (Coleoptera, Tenebrionidae) of the island of Thasos in the context of the Aegean Islands (Greece)

Abstract

This research aimed to study the origin and the biogeographical relationships of the tenebrionid beetle (Coleoptera, Tenebrionidae) fauna of the island of Thasos, with reference to the other Aegean Islands. A total of 32 Aegean Islands and 170 taxa (species and subspecies), 23 of which occur on Thasos, were included in this study. Nine tenebrionid species are here reported for the first time from Thasos, including the first records of Platydema europaeum and Nalassus plebejus from the Aegean Islands. Several models (linear, exponential, power, logistic, Gompertz, Weibull and Lomolino functions) were used to test the species-area relationship. The power function appeared to be the most appropriate model and the parameters of the curve suggest a possible relict character for this fauna. The proportion of Balkan taxa on the islands sharply decreases from west to east, whereas the Anatolian taxa follow an opposite trend. Multi-dimensional scaling, Parsimony Analysis of Endemicity and discriminant function analysis revealed a clear faunal discontinuity between the western and central Aegean Islands on one side, and the islands close to the Anatolian coast on the other. This discontinuity, consistent with the persistence (from Messinian to Pleistocene) of a sea barrier between these two groups of islands, strongly supports the importance of Pleistocene island configurations in determining present distributional patterns. The comparative richness of the tenebrionid fauna on Thasos is enhanced by the proximity of the island to the mainland and the diversity of its surviving habitats.

SPATIAL VARIATIONS IN RARITY IN THE AEGEAN TENEBRIONID BEETLES (Coleoptera, Tenebrionidae)

“…Taxonomic treatment and data concerning species distribution are the same as in Fattorini & Fowles (2006). As a whole, 170 taxa (138 species and 32 subspecies) were ascertained to occur as native populations on the study islands.…”

“…Fattorini & Fowles 2006). On the Aegean Islands, several tenebrionid species are represented by different subspecies endemic to individual islands or groups of islands.…”

“…Médail & Quézel 1999;Troumbis & Dimitrakopoulos 1998;Sfenthourakis & Legakis 2001;Fattorini 2006a). In addition, the Aegean Islands are of high biogeographical and conservation interest because of their location at the crossroad between the Balkan and the Anatolian faunas (Dennis et al 2000;Fattorini 2002;Fattorini & Fowles 2006). For these reasons, the Aegean tenebrionids represent a faunal group deserving special attention for the conservation of nature in the Mediterranean.…”

Shapes and functions of species–area curves (II): a review of new models and parameterizations

“…Flather (1996), who applied six different models to species-accumulation curves based on bird occurrences from roadside stops, reported that the Weibull distribution and the beta-P distribution produce the best fit. Fattorini & Fowles (2005) applied 10 different models to SARs of beetle species on Greek islands and have reported that the power model and the Weibull distribution produced the best fits. Fattorini (2007), who applied five models plus a linearized power model to the distribution of butterflies in Europe, reports the linearized power function and the Archibald logistic (which he calls the 'He-Legendre model') produces the best fit.…”

Are planar areas adequate for the species–area relationship?

“…Connor & McCoy 1979;Rosenzweig 1995;Williamson et al 2001Williamson et al , 2002Fattorini & Fowles 2005) studies showed that SARs can be most often modelled by a simple power function: S5CA z , where S is the species number in a given area A, and C and z are the parameters of the model, with C being an estimate of the mean number of species per unit area and z is a scaling coefficient that ranges frequently between 0.1 and 0.3. Also, this allometric function is simple to fit and the only one whose parameters can be assigned a biological meaning.…”