Sheep and cattle population dynamics based on ancient and modern DNA reflects key events in the human history of the North-East Baltic Sea Region

Genetic data from ancient and modern domestic animals holds tremendous potential to reveal long term trends in population histories. Reconstruction of effective population sizes based on temporally well covered data may reveal the effects of particular events in the early history of animal populations as well as reflect the changes in the lifestyle and society of past human populations. We used an Extended Bayesian Skyline Plot approach to estimate the effective population sizes (Ne) and their temporal changes in sheep and cattle from Late Bronze Age to present in North-East Baltic Sea Region (NEBSR). The results support previous results from ancient DNA analyses (mtDNA, Y-chromosome, MC1R) in the NEBSR for cattle and reveal previously unidentified temporal fluctuation for sheep (mtDNA, Y-chromosome). The sheep and cattle Ne increased during the Iron Age, reaching their maximum at the Late Iron Age/Medieval period followed by deep decline in sizes until the present. Decline in Ne simultaneously with increase in total population sizes indicate selection and increasing inbreeding from the beginning of Post Medieval period to the middle of the 20th century. The timing of the increase in sheep and cattle Ne is roughly the same as the timing of transition from hunting-gathering to farming in Iron Age (400-1000 CE).