Roman dogs from the Iberian Peninsula and the Maghreb - A glimpse into their morphology and genetics

Our results confirm the existence of distinct dog morphotypes in Roman times that also harboured distinct genetic lineages. According to our data, dogs from distinct mtDNA lineages (clades A and D) have been continuously bred in the Iberian Peninsula since at least 1600 years ago. Moreover, the sharing of matrilines between dogs from Spain and North Africa may indicate gene flow. Dogs could have been easily transported between these regions by humans along maritime and terrestrial trade routes. These results provide new insights into pre-Roman and Roman domestication practices, confirming selection practices were extensively applied to dogs during the first centuries of our era in the Iberian Peninsula. We show that the greater size variability of teeth length (and consequently cranium) and long bone breadths (and consequently phenotype) of Roman dogs in the Iberian Peninsula, is concomitant with the detection of diverse and rare maternal lineages. This would reflect an intensification of dog breeding and the use of non-local dogs for breeding.