Genetic and behavioral characteristics of the St. Kitts ‘island dog’

Recent studies of the ancient and indigenous dog breeds, while informing us about the origins of the domestic dog and the process of domestication, can also aid in understanding the behavior of modern-day dogs. Genetic signatures of indigenous American dog origins may be present on the Caribbean island of St. Kitts, where a population of largely free-roaming, mixed-breed street dogs exists in association with human residential areas. Behavior is the product of a complex interplay of genetic predispositions and individual experiences, and any distinctive behavioral tendencies present in this population of dogs may represent adaptations (in the evolutionary sense) to the human cultural context in which they evolved. We wished to assess whether the St. Kitts dog population represented a model of dogs of indigenous origin living in close association with humans, and thus be useful in understanding the relative importance of factors (genetic vs. environmental) contributing to the behavior of modern-day dogs. To address the question of whether ‘island dogs’ possess the genetic signature of an indigenous origin, we used both mitochondrial deoxyribonucleic acid (mtDNA) and Y chromosome typing to partially assess the ancestry and geographic origins of these dogs. To investigate whether ‘island dogs’ differed in behavioral characteristics from mixed breed dogs in a larger population (North America), we compared ‘island dog’ scores on the Canine Behavioral and Research Questionnaire (C-BARQ) with scores from North American mixed breed dogs. DNA haplotypes known to be associated with indigenous American dog origins were not found in the ‘island dogs’ sampled, and genetic analysis indicated a likely European (post-colonial) origin for these dogs. ‘Island dogs’ had significantly higher scores for non-social fear (p<0.02), defined as ‘showing fearful or wary responses to sudden or loud noises, traffic, and unfamiliar objects and situations’. It may be that neophobia and noise phobias have been selected for in ‘island dogs’, given the realities of living on the street with minimal direct human oversight and care. Alternately, these dogs may have become sensitized to certain types of stimuli, and have learned to be more fearful of novel situations and sounds, as such occurrences may represent a more serious threat than in North American households, where owners intervene frequently to manage risk and provide medical care. Overall, these ‘island dogs’ are likely responding to similar selection pressures and developmental influences as the North American dogs; factors associated with living within human cultures (i.e., selection pressures associated with domestication).