Hotspots of intraspecific diversity have been observed in most species, often within areas of putative Pleistocene refugia. They have thus mostly been viewed as the outcome of prolonged stability of large populations within the refugia. However, recent evidence has suggested that several other microevolutionary processes could also be involved in their formation. Here, we investigate the contribution of these processes to current range-wide patterns of genetic diversity in the Italian endemic mole Talpa romana, using both nuclear (30 allozyme loci) and mitochondrial markers (cytochrome b sequences). Southern populations of this species showed an allozyme variation that is amongst the highest observed in small mammals (most populations had an expected heterozygosity of 0.10 or above), which was particularly unexpected for a subterranean species. Population genetic, phylogeographic and historical demographic analyses indicated that T. romana populations repeatedly underwent allopatric differentiations followed by secondary admixture within the refugial range in southern Italy. A prolonged demographic stability was reliably inferred from the mitochondrial DNA data only for a population group located north and east of the Calabrian peninsula, showing comparatively lower levels of allozyme variability, and lacking evidence of secondary admixture with other groups. Thus, our results point to the admixture between differentiated lineages as the main cause of the higher levels of diversity of refugial populations. When compared with the Pleistocene evolutionary history recently inferred for species from both the same and other geographic regions, these results suggest the need for a reappraisal of the role of gene exchange in the formation of intraspecific hotspots of genetic diversity.

Macroinvertebrates are commonly used as environmental indicators in monitoring programs. Among crustaceans, amphipod communities play a relevant role in describing changes of sea bottom features, being therefore well appreciated as indicators. In this study the effects of sediment management off the Tyrrhenian coasts of Latium (Central Italy) have been assessed, using amphipod assemblages to monitor changes occurred in soft bottom areas before and after the perturbation. Results showed a variation in number of both individuals and species, with Ampelisca brevicornis (Costa, 1853), A. diadema (Costa, 1853), A. typica (Bate, 1856) and A. tenuicornis Liljeborg, 1855 as the most abundant species before sediment management, and Autonoe spiniventris Della Valle, 1893, Urothoe pulchella (Costa, 1853) and Medicorophium runcicorne Della Valle, 1893 as the most abundant ones after the perturbation. Amphipod assemblage appeared modified after sediment management showing an increase of species linked to sandy substrates. It is known that amphipod species have different degrees of sensitivity to environmental impacts but deeper studies concerning single species are problematic, also because of the limitation of a correct taxonomic classification of specimens based on morphological characters. With the aim to set up a tool for a quick and reliable assignment of the abundant genus Ampelisca, we have carried out a preliminary survey of a 658 bp (base pair) fragment of the mitochondrial cytochrome oxidase I (COI) gene, showing that some possible mis-assignments can occur based only on morphological characters.