Parasites as drivers of host diversification, including domestication

Parasites are ubiquitous evolutionary agents that, among other things, drive the diversification of hosts. This could also apply to animal domestication, one of the most striking evolutionary processes generating phenotypic diversity, which has recently been proposed as a parasite-mediated process (“The parasites-mediated domestication hypothesis”, PMD). The PMD is based on the fact that parasites can alter the (neuro)endocrine system (hypothalamic-pituitary-adrenal (HPA) axis, gut-brain axis, thyroid secretion, etc.), influence gene expression and ontogenetic systems, including neural crest cell development, and thus modulate physiological, behavioural and developmental components underlying the domestication. In this article, domestication is therefore placed in the context of parasite-driven diversification. The rationale for the parasite-mediated domestication process and associated diversification is supported by explanations of possible underlying mechanisms in light of the pioneering work of the Belyaev fox experiment and the later proposed hypothesis on the role of neural crest cells. Finally, a framework for plausible comparative and experimental approaches to test the PMD is proposed. Placing domestication in the context of the parasite-driven host diversification process provides a broad perspective for future research in the field of animal evolution and domestication.