Estimating the heritability of cognitive traits across dog breeds reveals highly heritable inhibitory control and communication factors (original) (raw)
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Breed Differences in Dog Cognition Associated with Brain-Expressed Genes and Neurological Functions
Integrative and Comparative Biology, 2020
Synopsis Given their remarkable phenotypic diversity, dogs present a unique opportunity for investigating the genetic bases of cognitive and behavioral traits. Our previous work demonstrated that genetic relatedness among breeds accounts for a substantial portion of variation in dog cognition. Here, we investigated the genetic architecture of breed differences in cognition, seeking to identify genes that contribute to variation in cognitive phenotypes. To do so, we combined cognitive data from the citizen science project Dognition.com with published breed-average genetic polymorphism data, resulting in a dataset of 1654 individuals with cognitive phenotypes representing 49 breeds. We conducted a breedaverage genome-wide association study to identify specific polymorphisms associated with breed differences in inhibitory control, communication, memory, and physical reasoning. We found five single nucleotide polymorphisms (SNPs) that reached genome-wide significance after Bonferroni correction, located in EML1, OR52E2, HS3ST5, a U6 spliceosomal RNA, and a long noncoding RNA. When we combined results across multiple SNPs within the same gene, we identified 188 genes implicated in breed differences in cognition. This gene set included more genes than expected by chance that were (1) differentially expressed in brain tissue and (2) involved in nervous system functions including peripheral nervous system development, Wnt signaling, presynapse assembly, and synaptic vesicle exocytosis. These results advance our understanding of the genetic underpinnings of complex cognitive phenotypes and identify specific genetic variants for further research.
Heritability of behavioural traits in domestic dogs: A meta-analysis
Applied Animal Behaviour Science, 2015
Reviews summarizing the literature on heritability of behavioural traits in dogs have been published repeatedly over the last four decades. The conclusions of these reviews vary to some extent. We applied meta-analysis and re-evaluated the literature available collecting 48 references dealing with heritability of behavioural traits in domestic dogs. For each study included, data was extracted for individual behavioural traits. Each of these traits was entered into the analysis as a separate unit of measure, giving a total of 1763 measures. We classified the traits measured in each study into five functional categories (Environment, Herding, Hunting, Play, and Psychical characteristic). The meta-analysis has shown low general heritability of the categorised behavioural traits analysed. Thus, the commonly used behaviour tests for many breeds, to determine the dog's eligibility for reproducing, traditionally required by many associations, is not supported by the present results of the meta-analysis.
Canine behavioral genetics — A review
Applied Animal Behaviour Science, 1986
A chronological review of the history of research in canine behavioral genetics is presented. Prior to the work of Scott and Fuller, many studies attempted to describe observed results in simple Mendelian terms. More recently, a quantitative mode of inheritance has been ascribed to many behavioral traits, and heritabilities have been calculated in different populations. Studies of behavioral traits are complicated by the effects of learning, which may well explain the reports of low heritability of behavioral traits measured on adults. Both genotype and environment have been shown to play major roles in the expression of behavioral traits. Maternal effects and the sex of an individual have important effects on behavior scores. Breeders usually select for both physical and behavioral traits in the same individuals, and this review includes a summary of reported research on the relationships between physical and mental traits.
Heritability and correlations among learning and inhibitory control traits
Behavioral Ecology, 2020
To understand the evolution of cognitive abilities, we need to understand both how selection acts upon them and their genetic (co)variance structure. Recent work suggests that there are fitness consequences for free-living individuals with particular cognitive abilities. However, our current understanding of the heritability of these abilities is restricted to domesticated species subjected to artificial selection. We investigated genetic variance for, and genetic correlations among four cognitive abilities: inhibitory control, visual and spatial discrimination, and spatial ability, measured on >450 pheasants, Phasianus colchicus, over four generations. Pheasants were reared in captivity but bred from adults that lived in the wild and hence, were subject to selection on survival. Pheasant chicks are precocial and were reared without parents, enabling us to standardize environmental and parental care effects. We constructed a pedigree based on 15 microsatellite loci and implemente...
The genetic contribution to canine personality
Genes, Brain and Behavior, 2006
The domestic dog may be exceptionally well suited for behavioral genetic studies owing to its population history and the striking behavior differences among breeds. To explore to what extent and how behavioral traits are transmitted between generations, heritabilities and genetic correlations for behavioral traits were estimated in a cohort containing over 10 000 behaviorally tested German shepherd and Rottweiler dogs. In both breeds, the pattern of co-inheritance was found to be similar for the 16 examined behavioral traits. Furthermore, over 50% of the additive genetic variation of the behavioral traits could be explained by one underlying principal component, indicating a shared genetic component behind most of the examined behavioral traits. Only aggression appears to be inherited independently of the other traits. The results support a genetic basis for a broad personality trait previously named shynessboldness dimension, and heritability was estimated to be 0.25 in the two breeds. Therefore, breeds of dogs appear to constitute a valuable resource for behavioral genetic research on the normal behavioral differences in broad personality traits.
Effects of selection for cooperation and attention in dogs
Behavioral and Brain Functions, 2009
Background: It has been suggested that the functional similarities in the socio-cognitive behaviour of dogs and humans emerged as a consequence of comparable environmental selection pressures. Here we use a novel approach to account for the facilitating effect of domestication in dogs and reveal that selection for two factors under genetic influence (visual cooperation and focused attention) may have led independently to increased comprehension of human communicational cues. Method: In Study 1, we observed the performance of three groups of dogs in utilizing the human pointing gesture in a two-way object choice test. We compared breeds selected to work while visually separated from human partners (N = 30, 21 breeds, clustered as independent worker group), with those selected to work in close cooperation and continuous visual contact with human partners (N = 30, 22 breeds, clustered as cooperative worker group), and with a group of mongrels (N = 30). Secondly, it has been reported that, in dogs, selective breeding to produce an abnormal shortening of the skull is associated with a more pronounced area centralis (location of greatest visual acuity). In Study 2, breeds with high cephalic index and more frontally placed eyes (brachycephalic breeds, N = 25, 14 breeds) were compared with breeds with low cephalic index and laterally placed eyes (dolichocephalic breeds, N = 25, 14 breeds). Results: In Study 1, cooperative workers were significantly more successful in utilizing the human pointing gesture than both the independent workers and the mongrels. In study 2, we found that brachycephalic dogs performed significantly better than dolichocephalic breeds. Discussion: After controlling for environmental factors, we have provided evidence that at least two independent phenotypic traits with certain genetic variability affect the ability of dogs to rely on human visual cues. This finding should caution researchers against making simple generalizations about the effects of domestication and on dog-wolf differences in the utilization of human visual signals.
During the domestication process, dogs were selected for their suitability for multiple purposes, resulting in a variety of behavioral characteristics. In particular, the ancient group of breeds that is genetically closer to wolves may show different behavioral characteristics when compared to other breed groups. Here, we used questionnaire evaluations of dog behavior to investigate whether behavioral characteristics of dogs were different among genetically clustered breed groups. A standardized questionnaire, the Canine Behavioral Assessment and Research Questionnaire (C-BARQ), was used, and breed group differences of privately-owned dogs from Japan (n = 2,951) and the United States (n = 10,389) were analyzed. Results indicated that dogs in the ancient and spitz breed group showed low attachment and attention-seeking behavior. This characteristic distinguished the ancient group from any other breed groups with presumed modern European origins, and may therefore, be an ancestral trait. The dog (Canis familiaris) was the first animal to be domesticated 1 and today hundreds of different breeds are recognized. Breeds seem to be different in several aspects of their behavior due to the effects of artificial selection 2–5. Although breeds are traditionally classified by the jobs they were originally selected to perform, parallel selection for other traits, such as suitability as pets, has also affected modern breed-typical behavior 6. With the remarkable improvement of technologies available for genetic analysis, genetic relationships in dog breeds have recently been studied and genetic classifications of dog breeds have been constructed 7,8. As a result, although dog breeds have traditionally been classified by their roles in human activities, historical records, and physical phenotypes, it is now possible to classify them based on patterns of genetic variation 9–11. Cladogram analysis of dog genes showed the separation of several breeds with supposedly ancient origins from a large group of breeds with presumed modern European origins 7,8. Modern European breeds are the products of controlled breeding practices since the Victorian era, and because they have originated recently and lack deep histories, the genetic groups have short internodes and low bootstrap support. On the other hand, ancient breeds are highly divergent and are distinct from modern European breeds. Since the dogs from these ancient breeds are genetically related most closely to wolves, they may exhibit remnants of wolves' behavioral, morphological and physiological characteristics. The Canine Behavioral Assessment and Research Questionnaire (C-BARQ) is designed to provide dog owners and professionals with standardized evaluations of canine temperament and behavior 12. The