Reviewing an eco-biogeographic question at regional scale: the unexpected absence of a ubiquitous mammal species (Microtus savii, Rodentia) in coastal Southern Tuscany (central Italy)

We reviewed the historical and recent data about the unexpected absence of a generalist ubiquitous mammal (Savi's pine vole Microtus savii, Rodentia) from a large sub-regional coastal land reclaimed area of Tyrrhenian central Italy, trying to search for causes explaining it. We assessed the possible role of different factors for different sub-areas as, in primis, biogeographic isolation (Monte Argentario) and granulometric/geochemical soil characteristics (Maremma plain) linked to land reclaimed history. However, bioclimatic regime, and competition with other species in area of recent colonization, examined in relation to some specialized species traits could be added to explain the unexpected absence of this ubiquitous rodent. Comparing our data with other geographical areas with similar characteristics, we hypothesize that none of these factors can be considered individually determinant, but that the cause of this absence could be determined by their interaction among different causal factors. This note would stimulate future field sampling design aimed to test the different hypotheses here inductively proposed.