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- Persson, Mia, 1988-
(författare)
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Pawsitive selection : Genetics of dog-human communication
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Through domestication and recent selection, dogs have evolved a unique set of communicative skills to attract and redirect human attention. These social skills have not been seen to the same extent in socialised wolves and are therefore believed to have a significant genetic basis. The process of domestication and breed formation has also had effects on the structure of the dog genome that are favourable for genetic mapping. With a high amount of linkage and long haplotype blocks, fewer genetic markers are needed to find gene-trait associations in dogs than in humans. Dogs serve as an important research model for us since humans and dogs share several diseases, psychiatric disorders and behavioural traits.In Paper I, I recorded human-directed social behaviours during a two-minute unsolvable problem task in 500 laboratory beagles. The dogs were living at a breeding facility and had been bred, kept and handled under standardised conditions. Behaviours related to task solving and human-directed contact seeking were separated in a principal component analysis, indicating that the behavioural test can be used to study dog-human interaction. Narrowsense heritability (h2) of the largest principal component related to contact seeking behaviours was estimated to 0.23. This study found a significant genetic basis to the variation seen in human-directed contact seeking behaviours recorded in this population.Next, in Paper II, we collected and genotyped the DNA of 190 of the previously tested beagles with an HD Canine SNP-chip. To find genes associated with human-directed contact seeking I performed a genome-wide association study (GWAS), showing one significant and two suggestive single nucleotide polymorphism (SNP) markers on chromosome 26. The significant SNP is located within a gene named SEZ6L, previously associated with autism in human studies. Two adjacent SNPs with suggestive association were found within a gene called ARVCF, which has been associated with schizophrenia. To our knowledge, this was the first genome-wide study to present regions within the dog genome associated with inter-species communication in dogs.However, these results could have been unique to this beagle population, so Paper III aimed to verify our previous findings in additional dog breeds. We tested 100 Labrador retrievers and 61 golden retrievers with the same unsolvable problem-task used in Paper I. Their DNA was collected and each individual was genotyped by pyrosequencing on two of the previously identified SNPs. To study the effects of recent selection, the Labrador retrievers were divided into two types. The common type is mainly bred and used for dog shows and as a pet, while the field type is mainly bred and used for hunting purposes. In this study, we found that both markers varied in both dog breeds and was significantly associated with human-directed contact-seeking behaviours. Allele frequencies differed significantly between Labrador retriever types, suggesting that these loci have been affected by recent selection. In conclusion, Paper III verifies the results found in Paper II.Finally, in Paper IV we investigated the association between dogs’ human-directed social skills and previously known SNP markers in the oxytocin receptor (OXTR) region. The oxytocin system plays an important role in the formation of social bonds and may therefore also be important in the bond between dogs and humans. Here, we hypothesized that dogs receiving intranasal oxytocin respond differently to the hormone, depending on the receptor type. To investigate this, 60 golden retrievers were genotyped for SNP markers in the OXTR region and tested with the unsolvable problem task used in Paper I and III. An association was found between genotype and social behaviour in response to oxytocin administration. Dogs responded differently to oxytocin treatment, depending on OXTR genotype. In summary, this thesis contributes to the knowledge on genetic influence of interspecies communication in dogs.
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| 2. |
- Sauveroche, Mathilde, et al.
(författare)
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Hair cortisol in horses (Equus caballus) in relation to management regimes, personality and breed
- 2020
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Ingår i: Journal of Veterinary Behavior. - : Elsevier. - 1558-7878. ; 37
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Tidskriftsartikel (refereegranskat)abstract
- Hair cortisol is a promising biomarker to measure long-term stress since cortisol is incorporated into the hair shaft as it grows. However, few studies have previously assessed hair cortisol concentrations (HCC) in horses. In this study, HCC was evaluated in both mane hair from the neck and body hair from the withers in 153 horses of different breeds, from seven different stables with three different management regimes (Free-roaming horses, Riding school horses, Trotter horses). In addition, 4 hours of behavioral observations were performed at each stable, and for 43 of the horses, a personality survey was completed. Mane and withers HCC correlated moderately, but significantly (rs=0.48, p<0.001). Differences between the stables were found for both mane and withers hair (both p<0.01) and the stable with lowest HCC also showed highest occurrences of positive social and resting behaviors (both p<0.01). There were no significant differences in HCC between the management regimes even though Free-roaming horses showed less negative social behavior compared to Riding school horses (p=0.041) and Trotter horses (p=0.055). The personality traits Dominance, Anxiousness, and Excitability revealed weak to moderate correlations with mane HCC (rs=-0.34, p=0.027; rs=-0.46, p=0.002; rs=-0.31, p=0.043 respectively) which might suggest that personality could also be related to long-term stress levels in horses.
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| 4. |
- Sundman, Ann-Sofie, 1982-
(författare)
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Dog behaviour : Intricate picture of genetics, epigenetics, and human-dog relations
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dogs, Canis familiaris, share the lives of humans all over the world. That dogs, and the behavior of dogs, are of interest to many is therefore no surprise. In this thesis, the main aim has been to identify factors that affect dogs’ behaviours.The dog, Canis familiaris, is our first domesticated animal. Since domestication, various types of dogs have developed through adaptation to an environment shared with humans and through our selective breeding, resulting in a unique variation in morphology and behaviour. Although there is an individual variation in the behaviour of dogs, there is also a difference between breeds. Moreover, selection during the last decades has split some breeds into divergent types. Labrador and golden retrievers are divided into a common type, for show and companionship, and a field type, for hunting. By comparing the breed types, we can study the effects of recent selection. In Paper I, we investigate differences in general behavioural traits between Labrador and golden retriever and between common and field type within the two breeds by using results from the standardized behaviour test Dog Mentality Assessment. There were differences between breeds and types for all behavioural traits. However, there was also an interaction between breed and type. Thus, a common/field-type Labrador does not behave like a common/field-type golden retriever. Even though they have been selected for similar traits, the selection has affected the general behavioural traits differently in the two breeds.In paper II, we were interested in dogs’ human-directed social skills. Dogs have a high social competence when it comes to humans. Two experiments commonly used to study these skills are the problem-solving test, where dogs’ human-directed behaviours when faced with a problem are measured, and the pointing test, where dogs are tested on how well they understand human gestures. We compared the social skills of German shepherds and Labrador retrievers, and of common- and field-type Labradors. Labradors were more successful in the pointing test and German shepherds stayed closer to their owners during the problem solving. Among Labrador types, the field type had more human eye contact than the common type. Importantly, when comparing the two experiments, we found no positive correlations between the problem-solving test and the pointing test, suggesting that the two tests measure different aspects of human-directed social behaviour in dogs.A previous study has identified two suggestive genetic regions for human-directed social behaviours during the problem-solving test in beagles. In paper III, we show that these SNPs are also associated to social behaviours in Labrador and golden retrievers. Moreover, the Labrador breed types differed significantly in allele frequencies. This indicates that the two SNPs have been affected by recent selection and may have a part in the differences in sociability between common and field type.The behaviour of dogs cannot simply be explained by genetics, there is also an environmental component. In paper IV, we study which factors that affect long-term stress in dogs. Long-term cortisol can be measured by hair samples. We found a clear synchronization in hair cortisol concentrations between dogs and their owners. Neither dogs’ activity levels nor their behavioural traits affected the cortisol, however, the personality of the owners did. Therefore, we suggest that dogs mirror the stress level of their owners.The mediator between genes and the environment is epigenetics, and one epigenetic factor is DNA methylation. In paper V, we compared methylation patterns of wolves and dogs as well as dog breeds. Between both wolves and dogs and among dogs there were substantial differences in methylated DNA regions, suggesting that DNA methylation is likely to contribute to the vast variation among canines. We hypothesize that epigenetic factors have been important during domestication and in breed formation.In this thesis, I cover several aspects on how dogs’ behaviours can be affected, and paint an intricate picture on how genetics, epigenetics, and human-dog relations forms dog behaviour.
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