Forest Dormouse (Dryomys nitedula) populations in southern Italy belong to a deeply divergent evolutionary lineage

Abstract

The Forest Dormouse (Dryomys nitedula) is a small rodent with a wide, albeit severely fragmented distribution, ranging from central Europe to central Asia. Within the Italian region, D. nitedula populations are restricted to forested mountain areas of two largely disconnected regions, the eastern Alps and the Calabria region, where two distinct subspecies (D. nitedula intermedius and D. nitedula aspromontis, respectively) have been described on the basis of phenotypic characters (i.e., fur colour). Here we analysed D. nitedula samples from both regions, to investigate patterns of genetic divergence and phylogenetic relationship among these two populations. Genetic variation was studied at the level of one mitochondrial (cytochrome b gene) and three nuclear gene fragments (exon1 of the interstitial retinoid-binding protein, exon 10 of the growth hormone receptor, and recombination activating gene 1). Phylogenetic analyses were performed using Maximum Likelihood and Bayesian inference methods. D. n. aspromontis and D. n. intermedius were found to be reciprocally monophyletic in all the phylogenetic analyses, and the genetic divergence observed between them at the mitochondrial CYTB gene was conspicuous (HKY: 0.044) when compared to previously observed values among many sister species of rodents. Our results clearly show that D. nitedula aspromontis is a deeply divergent, narrow endemic evolutionary lineage, and its conservation needs should be carefully evaluated in the near future. Moreover, such deep genetic divergence, together with phenotypic differentiation between D. n. intermedius and D. n. aspromontis, suggest that D. nitedula populations in southern Italy might belong to a distinct, previously unrecognized species.

Mammal endemism In Italy: A review

“…Previous studies did not show substantial cytogenetic and morphometric differences between the disjoined population of Calabria with those of the Alps (Civitelli et al 1995. Recent molecular studies (Bisconti et al 2017) have shown that the subspecies of Calabria D. nitedula aspromontis (see distribution in Fig. 5) is a deeply divergent evolutionary lineage representing a new endemic taxon to Italy.…”

“…The amount of sequence divergence suggested a divergence time between the Calabrian and north Italian population around one million years ago (i.e. the Early Pleistocene) (Bisconti et al 2017). Altobello, 1926.…”

Population genetic structure of the bank vole Myodes glareolus within its glacial refugium in peninsular Italy

“…The Calabrian region is a well-known glacial refugium for temperate species in peninsular Italy, 8 and provides one of the best examples of highly sub-structured refugia, a scenario known as refugia-within-refugia (Gomez & Lunt, 2007). Indeed, for most of the temperate species studied to date in this area, the Calabrian region provided suitable albeit fragmented habitats through most of Pleistocene, allowing long-term survival of relict populations (Bisconti et al, 2018;Senczuk, Colangelo, De Simone, Aloise & Castiglia, 2017). Accordingly, the Early-Middle Pleistocene origin of Calabrian bank vole populations was suggested by both molecular dating and fossil evidence (Colangelo et al, 2012;Sala & Masini 2007).…”

“…Strong genetic differentiation and high intra-specific variation of Calabrian populations is a fairly common pattern in both animal and plant species (Bisconti et al, 2018;Canestrelli et al, 2006;Canestrelli, Cimmaruta & Nascetti, 2008;Canestrelli, Aloise, Cecchetti & Nascetti 2010;Canestrelli, Sacco & Nascetti, 2012;Chiocchio, Bisconti, Zampiglia, Nascetti & Canestrelli, 2017;Hewitt, 2011;Vega, Amori, Aloise, Cellini, Loy & Searle, 2010). The Calabrian region is a well-known glacial refugium for temperate species in peninsular Italy, 8 and provides one of the best examples of highly sub-structured refugia, a scenario known as refugia-within-refugia (Gomez & Lunt, 2007).…”

“…Canestrelli, Cimmaruta, Costantini & Nascetti, 2006), often with narrow distribution (e.g. Bisconti et al, 2018)detecting which is crucial to understanding species genetic structure and to defining evolutionary and management units for conservation planning (Avise, 2008;Frankham, 2010;Groves et al, 2017;Palsbøll, Berube & Allendorf, 2007). However, despite their disproportionate importance for the historical biogeography of Western Palearctic biota, current knowledge of their biodiversity patterns is still far from satisfactory.…”