Sequenced genomes and chromosome mapping illuminate key aspects of satellite DNA biology in Drosophila gouveai and D. borborema (buzzatii cluster, repleta group)

Satellite DNAs are abundant components of the genomes of many eukaryotic species. They are composed of long and rather homogeneous arrays of tandem repeats that are typically located at the heterochromatin. They may contribute to the structural organization and regulatory dynamics of the genome. However, they evolve rapidly between species and changes in their sequences and abundance may contribute to the process of speciation. Here we used Illumina genomic sequencing raw data and the TAREAN bioinformatic tool to identify and characterize the most abundant satDNAs present in two sister species from the buzzatii cluster (repleta group): D. gouveai and D. borborema. We found five satDNAs, two are reported in these species for the first time (CDSTR138 and CDSTR230), two have already been reported (pBuM and DBC-150) and one is described here for the first time (CDSTR8). These satDNAs differ in both quantitative and qualitative terms between the two species. Most notoriously, the pBuM satDNA was found in D. gouveai, but it is virtually absent in D. borborema, despite their relatively recent divergence (<0.5My). We mapped these satDNAs to the chromosomes and found that most of them are located near or at the centromeres, with overlapping distribution in several locations.