Jiang, Peiwen (ID: 1247142)
Theme 3: Effects of Human-Mediated Selection
Title: Origin of Dog Domestication: How Dogs Evolved to Become Man’s Best Friend
Background and rationale: Dogs as a man’s best friend has been a prevalent view point among modern day humans, and some even accept it as fact. However, the genetics behind what makes dogs so compatible with mankind, and the history of domestication are not well known to most. The time of divergence, and geographic origin of dog domestication has been greatly debated, though many firmly believe they are of Asian origin (research article). Many researchers have studied the effects of breeding programs on genetics (pure breed), however the genetics behind initial domestication of dogs from wild wolves has not been well studied. The three following publications focus on these areas, and most show similar findings.
Wang et al. 2013: Much unlike studies for the genetic component of phenotypic variation among modern breeds, the first transition stage involving transition from wolves to ancestral dogs has been understudied (Wang et al. 2013). Previous studies of the origin of dogs using mtDNA as well as Y chromosome has identified indigenous dogs from southeast Asia as the “basal lineage connecting to wild grey wolves” (Wang et al. 2013 p. 3). Populations of dogs and wolves split around 32kya with decreasingly common admixture due to undesirable traits of the hybridization (Wang et al. 2013). Wang et al. (2013) suggested that domestication of dogs may have been a continuous process beginning with commensal living and hunting between humans and scavenging wolves that were excluded from hunting packs. A series of evolutionary events selecting for genes in dogs, as well as parallel selection of genes in humans and dogs, lead to the modern day fully domesticated dogs (Wang et al. 2013). Wang et al. (2013) found that many genes involving digestive systems were under positive selective pressure. These genes included maltase glucoamylase gene which evolved as an adaptation for agricultural starch based food source in humans. Wang et al. (2013) also found genes involving sound and smell, were positively selected for. A unique finding by Wang et al. (2013) was the parallel genes under positive selection in both human and dogs. Among the 32 genes found by Wang et al. (2013) between orthologous gene pairs of humans and dogs, some of the significant genes include ABCG5/ABCG8, and SLC6A4. The ATP-binding cassette transporters superfamily (ABCG) functions in transporting dietary cholesterol (Wang et al. 2013), which was likely a common adaptation in dietary content. SLC6A4 involved in serotonin transport has been associated with decreased aggression in dogs, and in humans, any variation of the gene leads to a range of neurological abnormalities (Wang et al. 2013).
Freedman et al. 2014: Humans expanded out of Africa and came in contact with grey wolves, then through a complicated process dogs emerged as the only...