Domestication of the dog from the wolf was promoted by enhanced excitatory synaptic plasticity: a hypothesis.
Bottom Line: Here, we demonstrate that genes involved in glutamate metabolism, which account partially for fear response, indeed show the greatest population differentiation by whole-genome comparison of dogs and wolves.However, the changing direction of their expression supports a role in increasing excitatory synaptic plasticity in dogs rather than reducing fear response.Because synaptic plasticity are widely believed to be cellular correlates of learning and memory, this change may alter the learning and memory abilities of ancient scavenging wolves, weaken the fear reaction toward humans, and prompt the initial interspecific contact.
Affiliation: State Key Laboratory of Genetic Resources and Evolution, Yunnan Laboratory of Molecular Biology of Domestic Animals, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, China firstname.lastname@example.org email@example.com.Show MeSH
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Mentions: We firstly compared published resequenced genomes of three wolves and ten dogs (including five ancient dogs and five modern dogs, supplementary material, Supplementary Material online) to identify the most significant genetic legacy in the dogs deviating from their progenitors. To avoid inaccurate estimation of population differentiation due to small sample size, we only count the single nucleotide polymorphisms (SNPs) that differentiate extremely between the wolves and the dogs (allele frequency is 1 in wolves but 0 in dogs, or vice versa), which were defined as fixed SNPs. We identified 204 genes that have at least six fixed SNPs (within the 95% percentile rank). These genes showed an extremely significant lower level of nucleotide diversity and Tajima’s D values (P = 5.22E-05 and 1.23E-30, respectively, Mann–Whitney U test) compared with other genes in the genome (fig. 1A), suggesting a potential selection effects on the divergence observed here. Because only a very small number of fixed SNPs (totally 26) were nonsynonymous substitutions, this may indicate that the positive selection operated mainly on expressional regulation. Actually, the 204 genes showed appreciable changes in expression patterns between dogs and wolves than others for two different measurements: Absolute expression change and fold change (P = 0.022 and P = 0.005, respectively) (fig. 1B), based on the transcriptome data for the frontal cortex (Albert et al. 2012). These results suggest that expressional variation rather than structural variation in protein sequence is the major contributor to the currently observed differentiation between dogs and wolves.Fig. 1.—
Affiliation: State Key Laboratory of Genetic Resources and Evolution, Yunnan Laboratory of Molecular Biology of Domestic Animals, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, China firstname.lastname@example.org email@example.com.