Genetic legacy from past panmixia: high genetic variability and low differentiation in disjunct populations of the Eastern Large Heath butterfly

Biogeography of Italy revisited: genetic lineages confirm major phylogeographic patterns and a pre-Pleistocene origin of its biota

Warm-adapted species survived the cold stages of the past glacial-interglacial cycles in southern European peninsulas and recolonized major parts of Central and Northern Europe in the wake of postglacial warming. However, many of the genetic lineages which differentiated within these refugia predate even the Pleistocene. One of these refugia is the Italian Peninsula with its surrounding islands. In this meta-analysis, we compiled phylogeographic patterns of multiple species across this region. We transformed existing geographic information on 78 animal and plant species (with a total of 471 genetic lineages) within 17 predefined areas into presence/absence matrices. We elaborated three matrices: (i) only old lineages exclusively distinguished by deep splits, (ii) only young lineages distinguished by shallow (i.e. recent) splits, and (iii) presence/absence of the respective species. To infer biogeographic relationships between the predefined areas, we performed bootstrapped neighbour joining cluster analyses on these three matrices. In addition, we reviewed the geological history of Italy to identify causes of the observed biogeographic patterns. We found Sardinia and Corsica to be biogeographically closely linked with each other, and that they diverge strongly from all other regions. Sicily also diverges strongly from all other regions, while the intra-island differentiation was comparatively low. On the Italian mainland, Calabria exhibited the most pronounced biogeographic differentiation, often with several lineages present, resulting from old vicariance events within the region. Furthermore, southern Apulia and the Po Plain with adjoining areas of northern peninsular Italy displayed considerable distinctiveness. Admixture prevailed in the areas between these three regions. The ancient isolation of Sicily, as well as Sardinia plus Corsica, resulted in endemic lineages with only moderate recent exchange with adjacent mainland regions. Pronounced diversification occurs within the Italian Peninsula. The complex tectonic activities, such as shifting (micro)plates, submergence of major parts of peninsular Italy with the genesis of numerous Pliocene islands, in combination with the climatic cycles during the Pleistocene have most likely generated the current biogeographic pattern of species. Immigrations from the Balkan Peninsula into northern Italy partly accounted for the distinctiveness of this region.

Out of the alps: the biogeography of a disjunctly distributed mountain butterfly, the almond-eyed ringlet Erebia alberganus (Lepidoptera, Satyrinae)

Many studies on the biogeography of thermophilic and arctic-alpine species were performed during the past. Only little is known about species with intermediate characteristics. We analyzed the molecular biogeography of the butterfly Erebia alberganus (30 populations, representing 1106 individuals), sampled over the Alps, Apennines (Italy), and the Stara Planina (Bulgaria) using allozyme electrophoresis (17 loci). Genetic analyses revealed 3 major splits, with the strongest between the Stara Planina populations and all other populations, and a weaker split between the Alps and the Apennines. Individuals from the Apennines were genetically nested within the Alps group. The Alps cluster was segregated into 3 groups: the Southwestern, Western/Central, and Eastern Alps. The genetic diversities were highest for the Alps populations and significantly lower in the 2 isolates (Apennines, Stara Planina). The remarkable genetic split between Stara Planina and all other populations and the genetic distinctiveness of the former cluster might be interpreted as an ancient colonization event of this Balkan mountain range. The Apennines populations derive from a more recent expansion out of the Southwestern Alps. After surviving the Würm ice age most probably in the central Apennines, accompanied by genetic modification of some of these populations, northward expansion might have started from the western parts of the central Apennines reaching the northern Apennines during the early postglacial. The subtle genetic differentiation found among the Alps populations probably reflects 3 geographically disjunct Würm glacial centers located at the western slopes of the Southwestern Alps, at the southern slopes of the Central Alps, and in the Southeastern Alps.