Inferring Effective Past Population Size Changes of Italian Goat Breeds

Genomic data from livestock are revealing complex demographic trajectories and unexpected patterns of divergence and admixture. Reconstructing this history and estimating effective population size (Ne) is relevant toward effective conservation plans.  Here we use the Illumina Goat 50K SNP chip to predict a marker based Ne and its trend in 15 Italian goat breeds.  Assuming a generation length of 4 years, all breeds showed a consistent trend of population reduction from approximately 7.000 years ago towards the present.   Data suggest a decline of Ne size by one order of magnitude on average during the last millennia, reaching as few as ~500 Ne in the recent past.   In detail, Ne reduced by about half its size in ~5.000 years, while the last ~2.000 years showed the strongest decline, mainly in the last 250 generations.  Since low Ne suggests genetic diversity depletion - which is of concern for breed viability - these results prompt further analyses to understand the reasons for this drop and immediate conservation actions at the population level.