Author Correction: The spread of steppe and Iranian-related ancestry in the islands of the western Mediterranean.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The spread of steppe and Iranian-related ancestry in the islands of the western Mediterranean.

Steppe-pastoralist-related ancestry reached Central Europe by at least 2500 BC, whereas Iranian farmer-related ancestry was present in Aegean Europe by at least 1900 BC. However, the spread of these ancestries into the western Mediterranean, where they have contributed to many populations that live today, remains poorly understood. Here, we generated genome-wide ancient-DNA data from the Balearic Islands, Sicily and Sardinia, increasing the number of individuals with reported data from 5 to 66. The oldest individual from the Balearic Islands (~2400 BC) carried ancestry from steppe pastoralists that probably derived from west-to-east migration from Iberia, although two later Balearic individuals had less ancestry from steppe pastoralists. In Sicily, steppe pastoralist ancestry arrived by ~2200 BC, in part from Iberia; Iranian-related ancestry arrived by the mid-second millennium BC, contemporary to its previously documented spread to the Aegean; and there was large-scale population replacement after the Bronze Age. In Sardinia, nearly all ancestry derived from the island's early farmers until the first millennium BC, with the exception of an outlier from the third millennium BC, who had primarily North African ancestry and who-along with an approximately contemporary Iberian-documents widespread Africa-to-Europe gene flow in the Chalcolithic. Major immigration into Sardinia began in the first millennium BC and, at present, no more than 56-62% of Sardinian ancestry is from its first farmers. This value is lower than previous estimates, highlighting that Sardinia, similar to every other region in Europe, has been a stage for major movement and mixtures of people.

Body size structure of Pleistocene mammalian communities: what support is there for the "island rule"?

Islands are often regarded by scientists as living laboratories of evolution and an optimal context for the study of forces influencing evolution and diversification. Two main issues have been attentively scrutinized and debated: the loss of biodiversity and the peculiar changes undergone by island settlers, primarily changes in size of endemic vertebrates. Over time, several hypotheses have been formulated to explain the causal mechanism of body size modification. Faunas of those islands where mainland taxa migrate more than once provide the most interesting data to answer the question of whether or not trends of insular taxa result from a predictable response to differences in competition and availability of niches between insular and mainland environments. To contribute to the debate, the body size structure of the Pleistocene mammalian faunas from two Mediterranean islands, Sicily and Crete, were analyzed and compared with the structure of coeval mainland faunas. The results obtained suggest that: (i) size of endemic species does not directly depend on the area of islands; (ii) evolution and size of endemic species seems somewhat affected by the degree of isolation (constraining colonization from mainland) and physiography (sometimes permitting adaptive radiation); (iii) in unbalanced insular communities, the shift in size of non-carnivorous species largely depends on the nature of competing species; and (iv) body size of carnivorous species mainly depends on the size of the most available prey. Consequently, it is rational to suppose that the body size of insular mammals mainly results from the peculiar biological dynamics that characterizes unbalanced insular communities. Ecological interaction, particularly the intraguild competition, is the major driver behind the evolution of insular communities, leading towards an optimization of energy balance through a change in body size of endemic settlers.

Biochronology, paleobiogeography and faunal turnover in western Mediterranean Cenozoic mammals.

Cenozoic terrestrial mammals from Sardinia contribute substantial information for reconstructing the complex history of the western Mediterranean. The occurrence of endemic perissodactyls in Eocene marine and marsh deposits suggests the existence of ecological or physical barriers between the Corso-Sardinian massif and the Iberian-Occitanic area. At the end of the Oligocene, isolation of Sardinia was almost complete, although a migration from Europe occurred at the beginning of the Early Miocene, as indicated by the unbalanced endemic fauna from Oschiri. During the Late Miocene, the Tusco-Sardinian palaeobioprovince came into existence as an isolated region inhabited by the quite diversified, but notably endemic, Oreopithecus fauna. Sardinia was definitely isolated from Tuscany by the Messinian, but temporary connections with the European mainland possibly allowed the colonization of forerunners of some Sardinian Pliocene taxa. During the Plio-Pleistocene, Sardinia maintained permanent isolation. However, sea level drop, resulting in a relatively short distance between Sardinia and the European mainland, allowed different migratory events. From the Late Pliocene to the Late Pleistocene-Holocene, two main mammalian faunal complexes (FC) can be recognized: the Nesogoral FC (Late Pliocene-Early Pleistocene) and the Microtus (Tyrrhenicola) FC (late Early Pleistocene-Early Holocene). At the transition from Nesogoral to Microtus (Tyrrhenicola) FC, approximately 47% of the genera and 76% of the species disappeared, while approximately 58% of the genera and 71% of the species appeared. A noticeable turnover followed the arrival of Neolithic man and his accompanying fauna. Nonetheless, Praemegaceros was still present at about 7000 years BP, while Microtus (Tyrrhenicola) and Prolagus are respectively recorded in the Bronze and Iron Ages.