Sequence analysis, chromosomal distribution and long-range organization show that rapid turnover of new and old pBuM satellite DNA repeats leads to different patterns of variation in seven species of the Drosophila buzzatii cluster Gustavo C. S. Kuhn 1 *, Fabio M. Sene 2 , Orlando Moreira-Filho 1 , Trude Schwarzacher 3 & John S. Heslop-Harrison 3 1 Departamento de Gene´tica e Evoluc ¸a˜o, Universidade Federal de Sa˜o Carlos, Via Washington Luı´s, Km 235, 13565-905, Sa˜o Carlos, SP, Brazil; Tel: +55-(16)-3351-8431; Fax: +55-(16)-3351-8377; E-mail: gcskuhn@iris.ufscar.br; 2 Departamento de Gene´tica, Universidade de Sa˜o Paulo, Faculdade de Medicina de Ribeira˜o Preto, Ribeira˜o Preto, SP, Brazil; 3 Department of Biology, University of Leicester, Leicester, UK * Correspondence Received 25 September 2007. Received in revised form and accepted for publication by Mary Delany 7 December 2007 Key words: concerted evolution, Drosophila buzzatii, homogenization, molecular drive, satellite DNA Abstract We aimed to study patterns of variation and factors influencing the evolutionary dynamics of a satellite DNA, pBuM, in all seven Drosophila species from the buzzatii cluster (repleta group). We analyzed 117 alpha pBuM-1 (monomer length 190 bp) and 119 composite alpha/beta (370 bp) pBuM-2 repeats and determined the chromosome location and long-range organization on DNA fibers of major sequence variants. Such combined methodologies in the study of satDNAs have been used in very few organisms. In most species, concerted evolution is linked to high copy number of pBuM repeats. Species presenting low-abundance and scattered distributed pBuM repeats did not undergo concerted evolution and maintained part of the ancestral inter-repeat variability. The alpha and alpha/beta repeats colocalized in heterochromatic regions and were distributed on multiple chromosomes, with notable differences between species. High-resolution FISH revealed array sizes of a few kilobases to over 0.7 Mb and mutual arrangements of alpha and alpha/beta repeats along the same DNA fibers, but with considerable changes in the amount of each variant across species. From sequence, chromosomal and phylogenetic data, we could infer that homogenization and amplification events involved both new and ancestral pBuM variants. Altogether, the data on the structure and organization of the pBuM satDNA give insights into genome evolution including mechanisms that contribute to concerted evolution and diversification. Abbreviations BA Bahia state (Brazil) CENH3 centromeric histone H3 COI cytochrome oxidase I EDTA disodium ethylenediaminetetraacetate FISH fluorescence in situ hybridization FITC fluorescein isothiocyanate MG Minas Gerais state (Brazil) Mya million years ago Electronic supplementary material The online version of this article (doi:10.1007/s10577-007-1195-1) contains supplementary material, which is available to authorized users. Chromosome Research (2008) 16:307Y324 # Springer 2008 DOI: 10.1007/s10577-007-1195-1