Facultad de Ciencias

Seminario del 28 de marzo de 2019

Seminario Departamento de Biología. Arne Ludwig

In 2014 the 30th anniversary of ancient DNA (aDNA) research was celebrated in meetings and special issues publications worldwide. Considering these three decades, it is thus a good time both to highlight the striking transformations the field has undergone over the past 30 years, and to look forward to the future. Ancient DNA research started with a huge mistake; the first ever published aDNA sequence from an ancient Egyptian Mummy was a contamination of modern DNA. But this artifact founded the whole area of ancient DNA research which has been produced manifold insights into human history and evolution so far. The first reliable starting point of aDNA research was a short mitochondrial DNA fragment of 229 bp length from the quagga (Equus quagga quagga, an extinct, stripeless sub‐species of plain zebra). With the introduction of the polymerase chain reaction (PCR) around 1990, it became possible to target and replicate specific DNA sequences. Ancient DNA sequences obtained via PCR have allowed comprehensive phylogenetic studies and population genetics of both extinct and extant species, as well as functional studies of extinct genes and various aspects of domestication. However, in some fields PCR‐based studies remained controversial, such as aDNA studies on human pathogens. Furthermore, complete nuclear palaeogenomes were out of reach for any PCR‐based approaches. Almost all of these limitations have been overcome with the development of next generation sequencing (NGS) technologies that allow billions of sequences to be analyzed simultaneously. These technologies have not only enabled high‐coverage nuclear and mitochondrial genomes to be obtained from aDNA; they have also paved the way for other technical applications that have revolutionized research on aDNA in recent years, such as hybridization capture. Hybridization enrichment has been used to target full mitochondrial genomes, as well as for enrichment of nuclear DNA. It has been particularly important in re‐establishing studies on ancient pathogen DNA. Moreover, it has allowed the retrieval of the oldest aDNA sequences to date from non‐permafrost samples (∼400,000 year old), even from samples for which shotgun sequencing did not reveal any endogenous DNA. Given all these achievements, the direction and challenges of aDNA research are likely to change radically over the next decades. De-extinction of formerly lost species (mammoths, woolly rhinos etc.) seems to be in near distance. But there are still a lot of issues to solve before mammoths will walk around in Spain or anywhere else.