1. ¹Department of Biology, University College London, London NW1 2HE, UK
2. ²Department of Biology, The Centre for Genetic Anthropology, University College London, London NW1 2HE, UK
3. ³Center for Population Genomics and Pharmacogenetics, Duke Institute for Genome Sciences and Policy, Duke University, DUMC Box 3471, Durham NC 27710, USA
4. ⁴McDonald Institute for Archaeological Research, University of Cambridge, Downing Street, Cambridge CB2 3ER, UK
5. ⁵The Centre for Genetic Anthropology, University College London, London NW1 2HE, UK
6. ⁶Institute of Genetic Medicine, EURAC Research, 39100 Bolzano, Italy

Correspondence: Dr MG Thomas, Department of Biology, The Centre for Genetic Anthropology, University College London, Wolfson House, 4 Stephenson Way, London NW1 2HE, UK. Tel: +44 (020) 7 679 2654; Fax: +44 (020) 7 679 5052; E-mail: m.thomas@ucl.ac.uk

⁷Current address: School of Biological Sciences, Royal Holloway, University of London, Egham, TW20 0EX, UK.

⁸Current address: Department of Forensic Science and Chemistry, Anglia Ruskin University, East Road, Cambridge CB1 1PT, UK.

Received 5 April 2006; Revised 26 June 2007; Accepted 28 June 2007; Published online 22 August 2007.

Abstract

The Alps are one of the most significant geographical barriers in Europe and several isolated Swiss and Italian valleys retain the distinctive Ladin and Romansch languages, alongside the modern majority of Italian and German languages. Linguistically, Ladin belongs to the Romance languages, but some studies on mitochondrial DNA (mtDNA) variation have suggested a major Middle Eastern component to their genealogical origin. Furthermore, an observed high degree of within-population diversity has been interpreted as reflecting long-standing differentiation from other European populations and the absence of a major bottleneck in Ladin population history. To explore these issues further, we examined Y chromosome and mtDNA variation in two samples of Ladin speakers, two samples of German speakers and one sample of metropolitan Italian speakers. Our results (1) indicate reduced diversity in the Ladin-speaking and isolated German-speaking populations when compared to a sample of metropolitan Italian speakers, (2) fail to identify haplotypes that are rare in other European populations that other researchers have identified, and (3) indicate different Middle Eastern components to Ladin ancestry in different localities. These new results, in combination with Bayesian estimation of demographic parameters of interest (population size, population growth rate, and Palaeolithic/Neolithic admixture proportions) and phylogeographic analysis, suggest that the Ladin groups under study are small genetically isolated populations (subject to strong genetic drift), having a predominantly European ancestry, and in one locality, may have a greater Palaeolithic component to that ancestry than their neighbours.