Abstract
Genome-wide association study (GWAS) using dog breed standard values as phenotypic measurements is an efficient way to identify genes associated with morphological and behavioral traits. As a result of strong human purposeful selections, several specialized behavioral traits such as herding and hunting have been formed in different modern dog breeds. However, genetic analyses on this topic are rather limited due to the accurate phenotyping difficulty for these complex behavioral traits. Here, 268 dog whole-genome sequences from 130 modern breeds were used to investigate candidate genes underlying dog herding, predation, temperament, and trainability by GWAS. Behavioral phenotypes were obtained from the American Kennel Club based on dog breed standard descriptions or groups (conventional categorization of dog historical roles). The GWAS results of herding behavior (without body size as a covariate) revealed 44 significantly associated sites within five chromosomes. Significantly associated sites on CFA7, 9, 10, and 20 were located either in or near neuropathological or neuronal genes including THOC1, ASIC2, MSRB3, LLPH, RFX8, and CHL1. MSRB3 and CHL1 genes were reported to be associated with dog fear. Since herding is a restricted hunting behavior by removing killing instinct, 36 hounds and 55 herding dogs were used to analyze predation behavior. Three neuronal-related genes (JAK2, MEIS1, and LRRTM4) were revealed as candidates for predation behavior. The significantly associated variant of temperament GWAS was located within ACSS3 gene. The highest associated variant in trainability GWAS is located on CFA22, with no variants detected above the Bonferroni threshold. Since dog behaviors are correlated with body size, we next incorporate body mass as covariates into GWAS; and significant signals around THOC1, MSRB3, LLPH, RFX8, CHL1, LRRTM4, and ACSS3 genes were still detected for dog herding, predation, and temperament behaviors. In humans, these candidate genes are either involved in nervous system development or associated with mental disorders. In conclusion, our results imply that these neuronal or psychiatric genes might be involved in biological processes underlying dog herding, predation, and temperament behavioral traits.
Highlights
Dogs are man’s best friend and the first domesticated animal, originating from a now-extinct wolf population
Body Size as a Covariate We investigated four dog behavioral trait phenotypes using a univariate linear mixed model incorporating in GEMMA 0.98 [32]
Two, and eight significantly associated intron variants were detected in acid sensing ion channel subunit 2 (ASIC2), methionine sulfoxide reductase B3 (MSRB3), and regulatory factor X8 (RFX8) genes, respectively, on chromosomes 9 and 10 (Table 2)
Summary
Dogs are man’s best friend and the first domesticated animal, originating from a now-extinct wolf population. Dogs have shared living space and food sources with humans and have maintained this close relationship for more than 11,000 years [1]. For only 200–300 years, humans have selectively bred dogs for excellence in herding, hunting, and obedience and have created diverse breeds with a wealth of behaviors. Humans have bred dogs for different morphological traits such as body types, sizes, skull shapes, coat colors, and textures according to human preferences and needs. Two major bottlenecks in dog history, i.e., early domestication and the creation of modern breeds, have characterized long-range linkage disequilibrium (LD) within dog breeds, providing an excellent natural model for studying morphology, complex diseases, and behaviors [2]. Many cross-breed researches were performed including morphologic traits [3,4,5], diseases [6], behavior or cognition [6,7,8], and athletic ability [9]
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