Ontogeny of domestic dogs and the developmental foundations of carnivoran domestication

Abstract

Whereas hundreds of breeds of domestic dogs are known, only several dozen domestic cat breeds are currently recognized, and the ferret is not classified into specific breeds. We studied pre- and postnatal patterns of development and growth in the domesticated forms of these three carnivoran species. We present the most comprehensive staging system for domestic dog embryos to date and define qualitative characters for phylogenetic comparisons. For postnatal development, we present analyses of new and literature measurements of cranial and limb proportions. We analyze changes in the progress of growth among different domestic dog and domestic cat breeds. All three domesticated forms drastically differ in the relative timing of prenatal development. This is correlated with ontogenetic plasticity at birth, which enables artificial selection to act. For postnatal development, we detected a greater shape variance in domestic dog ontogeny when compared to that of the domestic cat. We conclude that ontogenetic preconditions as well as body size constrain the species’ capability for artificial selection in domestic dogs and cats. However, we speculate that the human requirements for functional performance of their domesticates might render some developmental biases substantially. Although ferrets would be preferable for artificial selection given their plastic embryonic development, they have been of less interest for domestication due to their small body size - by which they were already well adapted for hunting in burrows - and due to the fact that other relevant tasks were already assumed by domestic cats and dogs since earlier phases of human cultural evolution.