Long DNA sequences and large data sets: investigating the Quaternary via ancient DNA

Progress in technical development has allowed piecing together increasingly long DNA sequences from subfossil remains of both extinct and extant species. At the same time, more and more species are analyzed on the population level, leading to a better understanding of population dynamics over time. Finally, new sequencing techniques have allowed targeting complete nuclear genomes of extinct species. The sequences obtained yield insights into a variety of research fields. First, phylogenetic relationships can be resolved with much greater accuracy and it becomes possible to date divergence events of species during and before the Quaternary. Second, large data sets in population genetics facilitate the assessment of changes in genetic diversity over time, an approach that has substantially revised our views about phylogeographic patterns and population dynamics. In the future, the combination of population genetics with long DNA sequences, e.g. complete mitochondrial (mt) DNA genomes, should lead to much more precise estimates of population size changes to be made. This will enable us to make inferences about - and hopefully understand - the causes for faunal turnover and extinctions during the Quaternary. Third, with regard to the nuclear genome, complete genes and genomes can now be sequenced and studied with regard to their function, revealing insights about the numerous traits of extinct species that are not preserved in the fossil record. (C) 2008 Elsevier Ltd. All rights reserved.