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Distribution and clustering of genes preferentially expressed in specific tissues based on their length. A) Boxplot depicting the length of all human genes grouped by preferential expression. The letters under each box represent statistical similarity of the series (p-values

HD-, HN- and AMH-specific RI distribution in present-day populations. A-B) Heatmaps of respectively HD- and HN-specific RI distribution in present-day populations. Each line of the maps represents a single insertion, intensity of the color from grey to green reflects the frequency in modern populations. Arrows indicate three insertions that were identified as shared between HN and HD, rectangles highlight insertions that are putatively introgressed in modern populations post Out-of-Africa. C) Simulated curve representing random sampling of AFR individuals for the identification and exclusion of polymorphic archaic-specific insertions. Red dotted lines indicate 95% confidence intervals. D) Heatmap of AMH-specific RI distribution in in present-day populations: each line of the map represents a single insertion, intensity of the color from grey to purple reflects the frequency in modern populations. E) Neighbour joining tree calculated by using AMH-specific RIs in present-day populations as phylogenetic markers. Branches in orange are from populations with African descent, blue for European descent, green for South-Asian descent, red for East-Asian descent and black for Native-American descent, as clustered by RI distribution. (PDF 229 kb)

Transposable elements (TEs) play an essential role in shaping eukaryotic genomes and generating variability. Speciation and TE activity bursts could be strongly related in mammals, in which simple gradualistic models of differentiation do not account for the currently observed species variability. In order to test this hypothesis, we designed two parameters: the Density of insertion (DI) and the Relative rate of speciation (RRS). DI is the ratio between the number of TE insertions in a genome and its size, whereas the RRS is a conditional parameter designed to identify potential speciation bursts. Thus, by analyzing TE insertions in mammals, we defined the genomes as "hot" (high DI) and "cold" (low DI). Then, comparing TE activity among 29 taxonomical families of the whole Mammalia class, 16 intra-order pairs of mammalian species, and four superorders of Eutheria, we showed that taxa with high rates of speciation are associated with "hot" genomes, whereas taxa with low ones are associated with "cold" genomes. These results suggest a remarkable correlation between TE activity and speciation, also being consistent with patterns describing variable rates of differentiation and accounting for the different time frames of the speciation bursts. Correction in: Journal of Molecular Evolution, vol. 86, issue 5, pages 311-311. DOI: 10.1007/s00239-018-9850-zThe original version of the article unfortunately contained tagging error in Given and Surname of all the authors. This has been corrected with this erratum.WoS title: Transposable Elements Activity is Positively Related to Rate of Speciation in Mammals (vol 86, pg 303, 2018)

Background Transposable elements are biologically important components of eukaryote genomes. In particular, non-LTR retrotransposons (N-LTRrs) played a key role in shaping the human genome throughout evolution. In this study, we compared retrotransposon insertions differentially present in the genomes of Anatomically Modern Humans, Neanderthals, Denisovans and Chimpanzees, in order to assess the possible impact of retrotransposition in the differentiation of the human lineage. Results We first identified species-specific N-LTRrs and established their distribution in present day human populations. These analyses shortlisted a group of N-LTRr insertions that were found exclusively in Anatomically Modern Humans. These insertions are associated with an increase in the number of transcriptional/splicing variants of those genes they inserted in. The analysis of the functionality of genes containing human-specific N-LTRr insertions reflects changes that occurred during human evolution. In particular, the expression of genes containing the most recent N-LTRr insertions is enriched in the brain, especially in undifferentiated neurons, and these genes associate in networks related to neuron maturation and migration. Additionally, we identified candidate N-LTRr insertions that have likely produced new functional variants exclusive to modern humans, whose genomic loci show traces of positive selection. Conclusions Our results strongly suggest that N-LTRr impacted our differentiation as a species, most likely inducing an increase in neural complexity, and have been a constant source of genomic variability all throughout the evolution of the human lineage. Electronic supplementary material The online version of this article (10.1186/s13100-018-0133-4) contains supplementary material, which is available to authorized users.

The Mediterranean shores stretching between Sicily, Southern Italy and the Southern Balkans witnessed a long series of migration processes and cultural exchanges. Accordingly, present-day population diversity is composed by multiple genetic layers, which make the deciphering of different ancestral and historical contributes particularly challenging. We address this issue by genotyping 511 samples from 23 populations of Sicily, Southern Italy, Greece and Albania with the Illumina GenoChip Array, also including new samples from Albanian-and Greek-speaking ethno-linguistic minorities of Southern Italy. Our results reveal a shared Mediterranean genetic continuity, extending from Sicily to Cyprus, where Southern Italian populations appear genetically closer to Greek-speaking islands than to continental Greece. Besides a predominant Neolithic background, we identify traces of Post-Neolithic Levantine-and Caucasus-related ancestries, compatible with maritime Bronze-Age migrations. We argue that these results may have important implications in the cultural history of Europe, such as in the diffusion of some Indo-European languages. Instead, recent historical expansions from North-Eastern Europe account for the observed differentiation of present-day continental Southern Balkan groups. Patterns of IBD-sharing directly reconnect Albanian-speaking Arbereshe with a recent Balkan-source origin, while Greek-speaking communities of Southern Italy cluster with their Italian-speaking neighbours suggesting a long-term history of presence in Southern Italy., This study was supported by the Genographic Project 2.0 (Geno 2.0) Scientific Research Grant 4–13 and by the European Research Council ERC-2011-AdG 295733 grant (Langelin).