Management and Personality in Labrador Retriever dogs

Abstract

Canine personality is of keen interest to dog owners and researchers alike. The regular human contact with them makes dogs an ideal species to use in the investigation of animal personality. This study specifically focused on Labrador Retrievers, consistently one of the most popular breeds both in the UK and around the world. Using surveys completed by dog owners, data was gathered on the behaviour of the dogs, in addition to the physical characteristics and management characteristics of the dogs (n = 1978). Twelve personality traits were identified and investigated for associations with the demographic data. It was found that the working status of the dog was more commonly associated with differences in personality than other analyzed factors. Gundogs had higher scores for ‘fetching tendency’ and ‘trainability’ than Showdogs or Pets (P < 0.05). Chocolate dogs were more ‘agitated when ignored’ and showed more ‘excitability’ than black dogs, and lower ‘trainability’ and ‘noise fear’ than both yellow and black dogs (all P < 0.05). Dogs exercised for longer periods showed less aggression, less fear of humans and objects and lower separation anxiety than dogs that were not as active. The effects observed in this study may be due to the experience and training of the dogs, the work-related genetic strain of Labrador Retriever or most likely, a combination of both influences.

Full text

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Management and Personality in Labrador Retriever dogs
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Sarah E. Lofgren1, Pamela Wiener2, Sarah C. Blott3, Enrique Sanchez-Molano2, John A.
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Woolliams2, Dylan N. Clements1,2, Marie J. Haskell4
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1. Royal (Dick) School of Veterinary Science, University of Edinburgh, Easter Bush,
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Scotland, UK
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2. Roslin Institute, Royal (Dick) School of Veterinary Science, University of Edinburgh,
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Easter Bush, Scotland, UK
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3. Animal Health Trust, Newmarket, UK
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4. Scotland’s Rural College, West Mains Road, Edinburgh, Scotland, UK
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Abstract
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Canine personality is of keen interest to dog owners and researchers alike. The
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regular human contact with them makes dogs an ideal species to use in the investigation of
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animal personality. This study specifically focused on Labrador Retrievers, consistently one
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of the most popular breeds both in the UK and around the world. Using surveys completed
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by dog owners, data was gathered on the behaviour of the dogs, in addition to the physical
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characteristics and management characteristics of the dogs (n=1978). Twelve personality
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traits were identified and investigated for associations with the demographic data. It was
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found that the working status of the dog was more commonly associated with differences in
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personality than other analyzed factors. Gundogs had higher scores for ‘fetching tendency’
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and ‘trainability’ than Showdogs or Pets (P<0.05). Chocolate dogs were more ‘agitated
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when ignored’ and showed more ‘excitability’ than black dogs, and lower ‘trainability’ and
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‘noise fear’ than both yellow and black dogs (all P<0.05). Dogs exercised for longer
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periods showed less aggression, less fear of humans and objects and lower separation
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anxiety than dogs that were not as active. The effects observed in this study may be due to
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the experience and training of the dogs, the work-related genetic strain of Labrador
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Retriever or most likely, a combination of both influences.
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Keywords: Labrador Retriever, Management, Personality, Demographics, C-BARQ,
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canine
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1. Introduction
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It is commonly observed that individual animals show consistency in the way they
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respond to situations, and that the intensity of the response varies between individuals. In
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farm animals this phenomenon is termed temperament (Burrow and Corbet, 2000, Hoppe et
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al., 2010). However, in dogs it is often called personality (Svartberg et al. 2005, Ley et al.,
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2008), and this is the convention that we will follow for this paper.
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An animal's personality arises from the influences of both genetics and its
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environment, including previous experience. Prenatal experience has been shown to have
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long term effects on personality and other traits. Zebra finch eggs injected with testosterone
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produced birds that habituated quicker to novel food (Tobler and Sandell, 2007). Sows born
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to mothers that experienced social stress during pregnancy show more restlessness and
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aggression toward their own piglets (Jarvis, et al., 2006). There are also many postnatal
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influences that determine an animal's personality. Critical periods in early life are known to
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affect the long-term behaviour of the dog (Scott and Marston, 1950). The time at which a
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puppy is introduced to humans is critical, with earlier introduction resulting in more
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positive reactions towards humans in adulthood (Freedman el al., 1961). Svartberg et al.
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(2005) also found that dogs' reactions to some tests changed following later repetition, such
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as tests intended to provoke aggression using unusual stimuli. Although the individual dogs'
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reactions changed, the relative ranking of the dogs remained the same. Since personality is
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unique to each individual animal, it can be influenced by other factors and experiences in
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the animals’ life history. Kutsumi et al., (2013) found that puppy training classes improved
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long term obedience as well as response to strangers. McMillan et al., (2013) found that
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puppies obtained from pet stores scored less favorably on a personality assessment than
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puppies from non-commercial breeders, such that pet store dogs showed higher aggression
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and separation-related problems than dogs purchased from breeders. Later retesting
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produced similar results, showing that early experience has a long-term effect on the
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personality of the dogs.
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The genetic influence on animal personality has often been studied in terms of breed
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differences. Differences in temperament were found between breeds of cattle which were
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raised in identical environments (Hoppe et al., 2010). These differences are presumably due
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to genetic differences, since other variation had been removed. Dog breeds are well known
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to show differences in personality (Hart and Hart, 1995). Dachshunds and Chihuahuas have
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shown higher aggression toward humans, while Akitas and Pit Bull Terriers show higher
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dog-directed aggression (Duffy et al., 2008). Personality traits, including aggression, have
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also been shown to be heritable in dogs in a number of studies (Liinamo et al., 2007;
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Mackenzie, et al., 1986; Goddard and Beilharz, 1983; Saetre et al., 2006), which could
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have implications for breeding programmes. This is especially true for working dogs, since
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an appropriate personality is important to fulfilling their duties. Additionally, Svartberg et
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al., (2006) found that recent selection pressures have affected personality, with personality
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being more highly correlated with the current role of the dogs than with the breed's original
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purpose. For instance, breeds that are currently popular as house pets show higher
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playfulness regardless of the breeds' original purpose. The same experience is likely to
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affect genetically different individuals in different ways (Stamps and Groothius, 2010).
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As personality traits have been shown to be influenced by both genetic and non-
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genetic ('environmental') factors, it is of interest to determine the relative importance of
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these different factors. In this case, ‘environment’ is defined as the management and
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housing conditions experienced by domestic dogs. ‘Physical’ traits, such as age, sex and
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bodyweight, are also likely to influence personality. Therefore the aim of this study was to
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determine how personality traits are affected by physical and management factors in dogs.
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In order to account for the complexity of the study a large sample size was needed. In order
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to accomplish this, surveys were sent to several thousand dog owners. The Canine
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Behaviour and Research Questionnaire (C-BARQ), developed at the University of
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Pennsylvania, was used for this study (http://vetapps.vet.upenn.edu/cbarq/). Originally
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developed as a method for evaluating and predicting the success of guide dogs (Serpell and
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Hsu, 2001), this survey can be filled out by any dog owner. It covers many behavioural
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responses which are categorized into different aspects of animal personality. The survey
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responses are recorded on a 1 to 5 scale of the intensity of behavioural response to various
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situations. This is very similar to the approach of Svartberg and Forkman (2002), except the
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ratings are made by owners instead of a separate observer, and the behaviours recorded are
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elicited by normal interactions instead of induced by the test setup. The C-BARQ has been
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translated and used successfully in Japan (Nagasawa, et al., 2011), Taiwan (Hsu and Sun,
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2010), and the Netherlands (van den Berg et al., 2006), further demonstrating its generality.
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It has been used in the past to identify problematic behaviours being exhibited by individual
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dogs (Hsu and Serpell, 2003). It has also been used to study variation in specific traits
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among dogs. Using the C-BARQ, Duffy et al., (2008) found that levels of aggression
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towards people versus aggression towards dogs varies within and between breeds.
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For this study the issue of between-breed variation was eliminated by only studying
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a single breed, Labrador Retrievers registered with the UK Kennel Club. The overall aim of
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the study was to test for associations between the animal’s physical characteristics,
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lifestyle, potential genetic differences, and personality.
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2. Materials and Methods
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2.1. Surveys
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A survey was created to gather demographic and management data on the dogs
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participating in a larger study investigating the factors associated with canine hip dysplasia.
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It included 38 questions on physical traits such as weight, coat colour and health, as well as
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management data related to activities, housing, management and feeding (further details
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given below).
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The C-BARQ questionnaire consists of 102 questions pertaining to dog behaviour,
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divided into seven sections. The sections pertain to Training and obedience (8 questions),
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Aggression (25), Fear and anxiety (19), Separation-related behaviour (8), Excitability (6),
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Attachment and attention seeking (6), and Miscellaneous (Barking, chasing, unusual
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behaviours, etc.) (28).
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The demographic survey was sent by the UK Kennel Club to the owners of 12,408
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registered Labrador Retrievers which had known hip scores. Of these, 3071 surveys were
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completed and returned. The Canine Behavioural Assessment and Research Questionnaire
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(C-BARQ) surveys were distributed to the 2974 of those who had completed the first
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survey and also agreed to take part in the personality assessment. C-BARQ surveys were
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received for 2020 dogs.
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2.2. Personality trait analysis
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C-BARQ responses were recorded as letters A-E, with A representing a low or
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infrequent display of the behaviour in question, and E representing a high or frequent
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response. The C-BARQ data was transformed to numerical values, with A=1, B=2, C=3,
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D=4, E=5, and non-responses (N/A or Unanswered). Histograms were plotted for each
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question which were used to examine response variation for each question. Values for
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questions 6-8 (regarding disobedience) were reversed so ‘desirable’ was represented by a
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high score and ‘undesirable’ by a low score to be consistent with the other questions in that
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section. A description of the seven categories of behaviour are shown in Table 1.
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In order to define distinct personality traits, we investigated whether some of the
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questions referred to the same or closely related behavioural characteristics. A Principle
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Components Analysis (PCA) for correlation was run in Minitab 16 (Minitab Inc.) to
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determine whether the answers to individual questions related to each other. Questions with
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100 or more missing values were removed from analysis. This included questions 23, 32-
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36, 42, 50, 66, 71, 79, 87, and 103. These questions largely concerned multi-dog
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households or other situations that many owners and dogs had never been exposed to.
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Surveys missing any responses from the remaining questions were removed due to the
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constraints of the PCA. This resulted in a final sample size of 1077 surveys covering 89
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questions. The first three components of the PCA accounted for 13%, 6.6%, and 3.9% of
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the variation, respectively. On the basis of the clustering of the question level traits (Figure
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1), they were combined into ‘personality traits’ by taking the mean of the responses to
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questions within each PCA-defined group of traits, with the added constraint that the
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questions were from the same category in the C-BARQ questionnaire (Hsu & Serpell,
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2003; http://vetapps.vet.upenn.edu/cbarq/). For example, the trait of Owner aggression was
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calculated by averaging the values of all the questions that pertained to aggressive
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behaviour directed at the owner of the dog (Questions 10,14,15,18,20,26,31).
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Urinating/defecating was removed due to very low variation (all dogs had low scores). The
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correlations between the 18 remaining personality traits (Supplementary Table 1) were then
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calculated with the aim of further combining highly correlated traits (>0.4), again with the
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constraint that the questions were from the same category in the questionnaire
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(Supplementary Table 2). All questions included in the highly correlated traits were
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averaged to create the new trait in the same process as described above. If a survey had
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missing values for more than half the questions used to make up a personality trait, that
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individual did not receive a value for that trait.
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This analysis resulted in a final group of 12 personality traits: Agitated when
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Ignored, Attention Seeking, Barking Tendency, Excitability, Fetching, Human and Object
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Fear, Noise Fear, Non-Owner Aggression, Owner Aggression, Separation Anxiety,
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Trainability, and Unusual Behaviour (Supplementary Table 3).
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2.3. Management/Physical Traits
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Following a quality control procedure to remove questionnaires missing key data,
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complete C-BARQ surveys and management and physical characteristics data were
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available for 1978 dogs. Age at the time of survey completion was calculated from the date
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of birth and the survey received date. Age was then rounded to the nearest 0.5 years. Dogs
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were aged between 2 and 9.5 years. Measurements made in Imperial units were converted
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to SI units. Body mass index (BMI) was calculated as Girth divided by Length squared.
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Dogs were separated into categories based on their Working Status. These categories were
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Pets, Gundogs, and Showdogs. Dogs that were reported as ‘Other’ were either reassigned
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based on information provided in the comments or removed, resulting in a final sample size
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of 1,978. Dogs that were reported as being both Pets and Gundogs were classified as
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Gundogs, while dogs classified as Showdogs and Pets were grouped with Showdogs. Dogs
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were classified as living Indoor, Outdoor, or Indoor/Outdoor based on where they were
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reported to spend most of their time throughout the year. For instance, if a dog spent most
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of its time in a run, outdoor kennel, or yard, it was classified as Outdoor. If it spent most of
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its time in a house or garage, it was classified as Indoor. Dogs that were classified as Indoor
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for one half of the year and Outdoor for the other comprise the Indoor/Outdoor category.
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Gender Status was used to combine the Gender and Neuter responses. This resulted in four
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possible categories: Entire Males (EM) for uncastrated dogs, Entire Females (EF) for
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unneutered bitches, Neutered Males (NM) for castrated dogs, and Neutered Females (NF)
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for neutered bitches. Coat Colour was limited to the three main colours of Black,
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Chocolate, and Yellow. The small number of dogs that reported a coat colour of Fox Red
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(5), Liver (17), or Black and Tan (2) were grouped with the three categories Yellow,
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Chocolate, and Black, respectively. Health Status was determined by the presence of a
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disease or veterinary condition, with dogs either identifying as healthy (0) or having a
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significant health problem (1). No single health problem occurred with high enough
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frequency to be examined independently. Exercise was categorized into 1 (up to one hour
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per day), 2 (1-2 hours), 3 (2-4 hours), or 4 (more than 4 hours).
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Sire ID was used to identify full or half siblings and was used to account for any
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variation due to family relationships. Of the study dogs, 693 had sires which had no other
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progeny in our study. The remaining 1285 dogs had sires that had between 2 and 37
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progeny in our sample (mean family size=1.91, median=1). In summary, eight factors were
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extracted from the demographic survey for use in subsequent analysis: Age, BMI, Coat
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Colour, Gender Status, Health Status, Indoor/Outdoor Housing, Exercise, and Working
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Status.
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2.4. Statistical model-building
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Models were analyzed in Genstat 15 (VSN International, 2000-2013) using the
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General Linear Mixed Models option with Sire Identity as the random term. The binomial
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variable of Health Status was analyzed using a Binomial model with a binomial total of 2
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and a Logit link function. Variables that had a normal distribution were analyzed using a
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Normal model with an Identity link function. Variables where the distribution of responses
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was right-skewed were analyzed using a Poisson model with a Logarithm link function.
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The single variable where the distribution was left-skewed (Fetching) was a single-question
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personality trait and was therefore analyzed using a Binomial model with a binomial total
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of 5 and a Logit link function.
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For constructing the models we followed a set of rules designed to determine the
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explanatory variables that influenced each of the twelve response variables. The eight
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explanatory variables were all included in the model together. The variables with the
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highest p-values were then removed singly until all variables in the model had p-values <
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0.200
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2.4.1. Interactions
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All two-way interactions between the demographic factors were checked by
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including only the two independent variables and the interaction between them in the
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model. Only interactions which returned a p-value of 0.05 or lower during this analysis
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were included in the next step. These interactions were added simultaneously to the
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previously established model of demographic factors. Those with the highest p-values were
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removed until all interactions in the model had a p-value < 0.05, leading to the final model.
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Effect size was determined by taking the largest difference between means for a
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single factor in the final model, e.g. the difference between Chocolate and Black dogs for
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Agitated when Ignored. Average effect size is the mean of all significant effects within a
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factor.
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3. Results
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A different full model was used for each response variable. Variables included in
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the models and their significance are shown in Table 2; interactions present in the model
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are shown in Table 3, and effect sizes are shown in Table 4.
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3.1. Working Status
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The factor significantly associated with the most response variables was the
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Working Status of the dogs (Figure 2). Working Status featured in all models except
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Separation Anxiety, and was significantly associated with all response variables except
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Separation Anxiety and Owner Aggression. There was an average effect size of 0.33 over
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all significant associations, the highest of all factors. Pets and Gundogs were more Agitated
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when Ignored than Showdogs. Gundogs exhibited more Attention Seeking than Showdogs
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and Pets. Pets showed greater Barking Tendency and Excitability than Gundogs. Gundogs
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showed higher Fetching Tendency than Showdogs or Pets, and this factor had the largest
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effect size (1.32). Pets and Gundogs exhibited more Human and Object Fear than
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Showdogs. Pets showed greater Noise Fear than Gundogs or Showdogs. Pets showed more
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Non-Owner Aggression than Showdogs. Gundogs exhibited greater Trainability than Pets,
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and both were greater than Showdogs. Finally, Showdogs and Pets were more likely to
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exhibit Unusual Behaviours than Gundogs.
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3.2. Coat Colour
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Coat Colour was also shown to be associated with several response variables, and
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had an average effect size of 0.19. Chocolate dogs were more Agitated when Ignored than
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Black dogs. Chocolate dogs showed more Excitability than Black dogs. Black dogs showed
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a higher Fetching Tendency than Chocolate dogs. Black and Yellow dogs showed higher
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Noise Fear than Chocolate. Yellow dogs showed more Separation Anxiety than Black dogs.
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Chocolate dogs exhibited lower Trainability and a higher incidence of Unusual Behaviour
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than Black or Yellow dogs.
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3.3. Exercise
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The amount dogs were exercised was significantly associated with several
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personality traits and had the third highest average effect size (0.17). Dogs exercised <1
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hour/day were more likely to become Agitated when Ignored than dogs exercised 1-4
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hours/day. Dogs exercised <1 hour/day had a greater Barking Tendency and greater Human
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and Object Fear than those exercised 4+ hours/day. Dogs exercised <1 hour/day were more
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Excitable than others. Dogs exercised 1-2 hours/day were more likely to show Non-Owner
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Aggression than dogs exercised 2+ hours/day. Dogs exercised 1-2 hours/day were more
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likely to show Owner Aggression than dogs exercised 2-4 hours/day. Dogs exercised <1 or
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2-4 hours/day showed more Separation Anxiety than those exercised 4+ hours/day. Dogs
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exercised 1+ hour/day had higher Trainability than dogs exercised <1 hour/day. Dogs
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exercised <1 hour/day were more likely to exhibit Unusual Behaviour than others, and dogs
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exercised <2 hours/day were more likely to exhibit these behaviours than dogs exercised 4+
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hours/day.
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3.4. Housing
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Housing had an average effect size of 0.13. Dogs kept Indoor/Outdoor were more
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likely than Outdoor dogs to become Agitated when Ignored, although Indoor dogs were not
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significantly different from either group. Outdoor dogs showed less Excitability and
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Human and Object Fear than others, and were less likely to show Noise Fear than Indoor
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dogs. Dogs kept Indoor/Outdoor were more likely to show Non-Owner Aggression than
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other dogs.
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3.5. Gender Status
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Gender Status also had an average effect size of 0.13, and played a significant role
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in nine traits (Attention Seeking, Excitability, Human and Object Fear, Noise Fear, Non-
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Owner Aggression, Owner Aggression, Separation Anxiety, Trainability, and Unusual
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Behaviour) (Figure 3). Entire dogs showed more Attention Seeking and Excitability, and
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lower Human and Object Fear and Noise Fear, than Neutered Females. All Females showed
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higher Non-Owner Aggression than Entire Males, and Entire Males showed higher Owner
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Aggression than females. Entire Males showed higher Separation Anxiety than all other
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categories. Entire Females had higher Trainaibility than Neutered Females. All Females
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showed a higher incidence of Unusual Behaviour than Entire Males.
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3.6. Health, Age, BMI
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Health Status had an average effect size of 0.069, the lowest of the categorical
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variables. Healthy dogs were more likely to exhibit Attention Seeking. Younger dogs were
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more likely to show Human and Object Fear. Dogs with a lower BMI were more likely to
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show Non-Owner Aggression.
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4. Discussion
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Given that the survey data by owners is subjective in nature, there is potential for
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inaccuracy. The large sample size of this study may counter potential imprecision in
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judgment. Furthermore, multiple questions targeting similar personality traits were
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grouped, further reducing the role of individual inaccuracies. The survey data does not
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allow us to directly investigate the causal relationship between variables. Therefore, these
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results must be discussed in terms of associations and causal relationships can only be
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hypothesized in most cases.
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4.1. Personality trait groupings
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The traits were grouped according to the PCA results and correlations. The most
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distinct trait group was that for Trainability which appeared separately from the others in
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the PCA (Figure 1). The questions from the Aggression section were consolidated into two
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traits: Non-owner and Owner Aggression. Stranger, Dog, and Animal Aggression were
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highly correlated with each other, but not with Owner Aggression. This indicates that there
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are some fundamental differences between the expression of aggression towards human
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owners and other people and animals in the Labrador Retriever. Previous studies with the
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C-BARQ in a range of breeds have separated aggression into three categories, towards
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owners, strangers, and dogs (Hsu and Serpell, 2003; Nagasawa et al., 2011; Serpell and
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Hsu, 2005). In a study comparing aggression in a large number of breeds, Labrador
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Retrievers were shown to exhibit below-average levels of aggression towards owners, dogs
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and strangers (Duffy et al., 2008).
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4.2. Effects of genetics and lifestyle
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Genetic and experiential differences are known causes of personality variation in
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dogs (Podberscek and Serpell, 1996). The variation in genetics and lifestyle was primarily
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examined through Working Status, Coat Colour, and Exercise. Other sources of variation
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were accounted for in the models, including Indoor/Outdoor Housing, Health Status and
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BMI, but are not discussed in detail because of their limited impact in the statistical
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analysis.
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4.2.1. Working Status
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Working Status was significantly associated with 10 out of 12 personality traits and
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had the largest average effect sizes, making it the most influential factor. There are a
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number of possible explanations for these effects: genetic differences between the Working
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Status categories, difference in management and/or training between the categories or a
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combination of the two influences. Additionally, differences in the effects of Working
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Status may be exaggerated by the movement of dogs from one category to another if their
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behaviour is inappropriate (i.e. a dog that does not perform well as a show dog becomes a
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pet). We will refer to this phenomenon as ‘category shift’.
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In terms of the genetic influence, our results may reflect a known division in this
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breed. Labrador Retriever breeders and dog researchers recognize two types of Labrador
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Retrievers, which are referred to as “conformation”-bred and “field” Labrador Retrievers in
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the U.S. (http://en.wikipedia.org/wiki/Labrador_Retriever, accessed 22/11/13; Duffy et al.,
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2008) or ‘show’ and ‘working’ strains in the UK (Craig, 2011). The former are generally
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seen in dog shows while the latter are the type generally used as gundogs in the UK.
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Genetic differences between the two strains may be the result of breeding animals for good
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'performance' in either Showdog or Gundog roles, where performance in either category is
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likely to be related to the dog’s behaviour and personality. Gundogs are working dogs and
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are expected to be responsive and obedient throughout long periods where activity
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(fetching/retrieval) is interspersed with periods of inactivity (waiting for the next shoot to
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take place), unlike Pets and Showdogs that are not relied upon to complete specific tasks.
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The increased Attention Seeking, Fetching, and Trainability may relate to being attentive to
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the commands of the handler, performing the retrieval task reliably and being easily trained
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for all required tasks. Similarly the decreased Barking Tendency and Noise Fear of
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Gundogs may be attributed to their requirement to be quiet whilst working and between
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shoots, and unafraid of gunshot. Gundogs were also less likely to show Unusual
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Behaviours, which are often labeled as 'stereotypies'. It has been shown that stereotypies are
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negatively associated with stimulation and engagement (Sergiel et al., 2012). The lowered
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tendency to exhibit Unusual Behaviour in Gundogs may be due to the increased
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environmental complexity that is associated with being a working dog, although category
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shift could also explain the observed pattern.
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Showdogs have to tolerate distracting environments with many people and animals
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in close proximity and occasional physical handling by unfamiliar people, which may
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explain their lower scores for Agitated when Ignored, Human and Object Fear, Noise Fear
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and Non-owner aggression than Pets. The breeding of successful showdogs may have
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promoted these personality traits.
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However, previous training and experience may also explain some of these
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differences in personality traits. The behavioural phenotype recorded in the questionnaire
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may be influenced by the training or management regime of show and working dogs.
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Whilst the differences in Trainability could be due to deliberate breeding strategies in
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Gundogs, a Gundog will also undergo intensive training for its role, often by highly
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experienced trainers. Therefore, the behavioural phenotype that was recorded in the
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questionnaire may be influenced by this training, as has been shown in other studies
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(Svartberg, 2002; Kutsumi et al., 2013). Similarly, Showdogs may have been become
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desensitized to the multiple distractions of the dog show environment, and therefore react
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less to these stimuli (Kubinyi et al., 2009), and thus score lower in Excitability. Those that
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did not adapt well to either activity may have been removed due to category shift.
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It is likely that both genetic and training/experience influence the personality traits
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documented by the questionnaire in this population of dogs. An experimental approach
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would be required to disentangle these factors, in which behavioural outcomes are recorded
377

18
from Show and Gundog strains that are managed and trained in pet, show and gundog
378
environments.
379
4.2.2. Coat Colour
380
Chocolate Labrador Retrievers were different from Black and Yellow dogs for
381
several traits. Chocolate dogs had lower Noise Fear and Trainability, and exhibited more
382
Unusual Behaviour than yellow or black dogs. Additionally, Chocolate dogs were more
383
Agitated when Ignored, more Excitable, and had lower Fetching than black dogs. There are
384
two possible explanations for the differences. Firstly, the genes responsible for chocolate
385
coat colour could be genetically linked to the genes responsible for these personality traits,
386
which would make these characteristics likely to co-occur. The inheritance pattern of coat
387
colour has been studied in Labrador Retrievers and other breeds, and mutations in the
388
tyrosine related protein 1 gene (TYRP1) have been shown to be responsible for brown coat
389
colour in dogs (Templeton et al., 1977; Schmutz et al., 2002), however, genetic associations
390
between this gene and behavioural traits have yet to be investigated. Another explanation is
391
that in the attempts of dog breeders to produce a high frequency of Chocolate dogs, the
392
gene pool of dogs carrying the alleles for a Chocolate coat may have become somewhat
393
separated from that of the other Labrador retrievers. By chance, traits other than coat colour
394
may have higher frequencies in this gene pool, which could explain the differences in
395
personality. . Although the main difference was between Chocolate dogs and other dogs,
396
there were also some differences between Black and Yellow Labrador Retrievers (i.e.
397
Separation Anxiety).
398
4.2.3. Exercise
399

19
The level of exercise and stimulation a dog gets impacts its health and mental well-
400
being (Sergiel et al., 2012). The amount of time the dogs were exercised was associated
401
with 8 of the 12 personality traits, and it had the second highest effect sizes. Associations
402
with personality traits could be due to the level of exercise directly influencing the
403
expression of certain behaviours, or it could be that dogs showing unwanted traits are not
404
taken out by owners as much as other dogs, for fear of an inability to control them leading
405
to embarrassment or harm, which we will call 'Behavioural Deterrence'.
406
Dogs exercised less had higher Excitability, lower Trainability, and exhibited more
407
Unusual Behaviour. The association between high levels of exercise and Trainability is
408
likely in part due to an increased exposure to training during activity. Dogs exercised more
409
showed less Unusual Behaviour, supporting the idea that higher exercise levels are good for
410
the mental health of the dogs. The increased stimulation from human interaction and time
411
outside in novel environments may help to reduce the incidence of stereotypies (Menor-
412
Campos et al., 2011). This however is inconsistent with the results of Clark et al. (1997)
413
who found exercise had little effect on behaviour. The only behavioural difference they
414
found was an increase in barking among dogs exercised with a conspecific. However, the
415
periods of exercise used in their study were much shorter (20 minutes, 3 times a week) than
416
those reported here, suggesting that the quantity of exercise is important.
417
Dogs exercised more showed lower Non-Owner Aggression. This could be due to
418
increased exposure to unknown stimuli during prolonged activity. Frequent contact would
419
help familiarize the dog to strange people, animals and environments, and reduce the
420
likelihood of an aggressive response to novelty. This is supported by dogs exercised less
421
also showing higher Human and Object Fear, since fear and aggression have been shown to
422

20
be correlated in other studies (Duffy et al., 2008). Behavioural Deterrence may also account
423
for these patterns, such that dogs showing non-owner aggression are not walked as often in
424
order to avoid awkward situations for the owner.
425
Dogs exercised less showed higher Barking Tendency and Owner Aggression. This
426
may again be due to Behavioural Deterrence, or they may be barking to attract the attention
427
of owners or as an outlet for boredom. This is supported by the finding that dogs exercised
428
less also showed more Attention Seeking and less Separation Anxiety. Boredom may lead
429
to frustration, manifested as aggression towards the people within the household.
430
431
4.3. Gender and Age
432
Gender status was significant in relation to 9 out of the 12 traits. Gender status is a
433
combination of the sex and neuter status of the dogs, and both of these may have had an
434
effect on their personality. Gender status has previously been shown to be associated with
435
personality traits in dogs (Wilsson and Sundgren, 1997; Svartberg, 2002), including
436
aggressiveness and boldness. Personality differences between the groups are likely to be
437
due to hormonal differences.
438
Entire Males and Entire Females differed significantly from Neutered Females for
439
four traits. Neutered Females showed less Attention Seeking and Excitability, and showed
440
more Human and Object Fear and Noise Fear than the Entire dogs. Neutered Males were in
441
the middle and not significantly different from either group for all four of these traits.
442
Excitability may be higher in Entire than Neutered Females due to differences in hormone
443
levels.
444

21
Females showed more Non-Owner Aggression than Entire Males, and Entire Males
445
showed more Owner Aggression and less Unusual Behaviour than all Females, and higher
446
Separation Anxiety than all groups. Higher aggression among Males has been reported
447
previously (Hart and Hart, 1985, Wilsson and Sundgren, 1997). Castration of male dogs has
448
been shown to reduce aggressive dominance to some extent, but not territorial aggression
449
(Hart and Eckstein, 1997). The latter category may contain components of the Non-owner
450
Aggression category from the present study. However, higher Non-Owner Aggression from
451
Females was not been reported in either of these studies. This may represent a form of
452
territorial aggression, but levels of all aggression from this breed were low in this study.
453
The age of the dog is one of the easier factors to understand. The age of the animal
454
relates to its past experience, and therefore has an influence on its personality (Stamps and
455
Groothius, 2012). Older dogs showed significantly less Human and Object Fear. This is
456
possibly because experience has led them to discriminate between actual threats and
457
innocuous things. This is supported by older dogs showing less Separation Anxiety than
458
younger dogs, although this effect was not statistically significant. Older dogs have learned
459
their owners’ routines, and are less concerned about prolonged absences.
460
461
5. Conclusions
462
This large-scale study of behavioural characteristics in Labrador Retrievers revealed
463
a number of associations between physical, lifestyle and management characteristics of the
464
dogs and personality traits. The explanatory factor with the largest overall effect was the
465
working status of the dog, where pets showed dispositions that are generally considered
466
less desirable than those of gundogs and showdogs. The mechanism by which working
467

22
status could affect behaviour is not yet known, but it is likely to involve both genetic and
468
environmental factors. Further research is required to disentangle these factors. There were
469
also significant associations between personality traits and other factors considered,
470
including coat colour, levels of exercise, age, sex, neuter status and housing.
471
472
Acknowledgments:
473
We are very grateful to Professor James Serpell, of the University of Pennsylvania, for
474
allowing us to use C-BARQ in our study and for supplying additional information about the
475
questionnaire for Table 1. We would like to thank the UK Kennel Club for initially
476
contacting the dog owners. We are very grateful to all the owners of Labrador Retrievers
477
who completed and returned the surveys and made this study possible. Funding was
478
provided by the UK Biotechnology and Biological Sciences Research Council (grant
479
BB/H019073/1 and core funding to the Roslin Institute).
480
481
References:
482
Burrow, H.M., Corbet, N.J., 2000. Genetic and environmental factors affecting
483
temperament of zebu and zebu-derived beef cattle grazed at pasture in the tropics.
484
Australian Journal of Agricultural Research 51, 155-162.
485
Clark, J.D., Rager, D.R., Crowell-Davis, S., Evans, D.L., 1997. Housing and exercise of
486
dogs: effects on behavior, immune function, and cortisol concentration. Laboratory Animal
487
Science 47, 500-510.
488
Craig, D., 2011. The Labrador Retriever. Pet Book Publishing Company. PO Box Lydney
489
Gloucestershire GL15 6YD, United Kingdom.
490

23
Duffy, D.L., Hsu, Y.Y., Serpell, J.A., 2008. Breed differences in canine aggression.
491
Applied Animal Behaviour Science 114, 441-460.
492
Freedman, D.G., Elliot, O., King, J.A., 1961. Critical period in social development of dogs.
493
Science 133, 1016-1017.
494
Goddard, M.E., Beilharz, R.G., 1983. Genetics of traits which determine the suitability of
495
dogs as guide-dogs for the blind. Applied Animal Ethology 9, 299-315.
496
Hart, B.L., Hart, L.A., 1985. Selecting pet dogs on the basis of cluster-analysis of breed
497
behavior profiles and gender. Journal of the American Veterinary Medical Association 186,
498
1181-1185.
499
Hart, B.L. and Eckstein, R.A., 1997. The role of gonadal hormones in the occurrence of
500
objectionable behaviours in dogs and cats. Applied Animal Behaviour Science, 52, 331-
501
344.
502
Hoppe, S., Brandt, H.R., Konig, S., Erhardt, G., Gauly, M., 2010. Temperament traits of
503
beef calves measured under field conditions and their relationships to performance. Journal
504
of Animal Science 88, 1982-1989.
505
Hsu, Y.Y., Serpell, J.A., 2003. Development and validation of a questionnaire for
506
measuring behavior and temperament traits in pet dogs. Journal of the American Veterinary
507
Medical Association 223, 1293-1300.
508
Hsu, Y.Y., Sun, L.C., 2010. Factors associated with aggressive responses in pet dogs.
509
Applied Animal Behaviour Science 123, 108-123.
510
Jarvis, S., Moinard, C., Robson, S.K., Baxter, E., Ormandy, E., Douglas, A.J., Seckl, J.R.,
511
Russell, J.A., Lawrence, A.B., 2006. Programming the offspring of the pig by prenatal
512
social stress: Neuroendocrine activity and behaviour. Hormones and Behavior 49, 68-80.
513

24
Kubinyi, E., Turcsan, B., Miklosi, A., 2009. Dog and owner demographic characteristics
514
and dog personality trait associations. Behavioural Processes 81, 392-401.
515
Kutsumi, A., Nagasawa, M., Ohta, M., Ohtani, N., 2013. Importance of puppy training for
516
future behavior of the dog. The Journal of veterinary medical science / the Japanese Society
517
of Veterinary Science 75, 141-149.
518
Ley, J., Bennett, P., Coleman, G., 2008. Personality dimensions that emerge in companion
519
canines. Applied Animal Behaviour Science 110, 305-317.
520
Liinamo, A.-E., van den Berg, L., Leegwater, P.A.J., Schilder, M.B.H., van Arendonk,
521
J.A.M., van Oost, B.A., 2007. Genetic variation in aggression-related traits in Golden
522
Retriever dogs. Applied Animal Behaviour Science 104, 95-106.
523
Mackenzie, S.A., Oltenacu, E.A.B., Houpt, K.A., 1986. Canine behavioral genetics-A
524
review. Applied Animal Behaviour Science 15, 365-393.
525
McMillan, F.D., Serpell, J.A., Duffy, D.L., Masaoud, E., Dohoo, I.R., 2013. Differences in
526
behavioral characteristics between dogs obtained as puppies from pet stores and those
527
obtained from noncommercial breeders. Journal of the American Veterinary Medical
528
Association 242, 1359-1363.
529
Menor-Campos, D.J., Molleda-Carbonell, J.M., Lopez-Rodriguez, R., 2011. Effects of
530
exercise and human contact on animal welfare in a dog shelter. Veterinary Record 169,
531
388.
532
Nagasawa, M., Tsujimura, A., Tateishi, K., Mogi, K., Ohta, M., Serpell, J.A., Kikusui, T.,
533
2011. Assessment of the Factorial Structures of the C-BARQ in Japan. Journal of
534
Veterinary Medical Science 73, 869-875.
535

25
Podberscek, A.L., Serpell, J.A., 1996. The English Cocker Spaniel: Preliminary findings on
536
aggressive behaviour. Applied Animal Behaviour Science 47, 75-89.
537
Schmutz, S.M., Berryere, T.G., Goldfinch, A.D., 2002. TYRP1 and MC1R genotypes and
538
their effects on coat color in dogs. Mammalian Genome 13, 380-387.
539
Saetre, P., Strandberg, E., Sundgren, P.E., Pettersson, U., Jazin, E., Bergstrom, T.F., 2006.
540
The genetic contribution to canine personality. Genes Brain and Behavior 5, 240-248.
541
Scott, J.P., Marston, M.V., 1950. Critical periods affecting the development of normal and
542
mal-adjustive social behavior of puppies. Journal of Genetic Psychology 77, 25-60.
543
Sergiel, A., Maslak, R., Kusznierz, J., Pasko, L., 2012. Stereotypies: Development and
544
effects. Medycyna Weterynaryjna 68, 402-405.
545
Serpell, J.A., Hsu, Y.Y., 2001. Development and validation of a novel method for
546
evaluating behavior and temperament in guide dogs. Applied Animal Behaviour Science
547
72, 347-364.
548
Serpell, J.A., Hsu, Y.Y., 2005. Effects of breed, sex, and neuter status on trainability in
549
dogs. Anthrozoos 18, 196-207.
550
Stamps, J., Groothuis, T.G.G., 2010. The development of animal personality: relevance,
551
concepts and perspectives. Biological Reviews 85, 301-325.
552
Svartberg, K., 2002. Shyness-boldness predicts performance in working dogs. Applied
553
Animal Behaviour Science 79, 157-174.
554
Svartberg, K., Forkman, B., 2002. Personality traits in the domestic dog (Canis familiaris).
555
Applied Animal Behaviour Science 79, 133-155.
556
Svartberg, K., Tapper, I., Temrin, H., Radesater, T., Thorman, S., 2005. Consistency of
557
personality traits in dogs. Animal Behaviour 69, 283-291.
558

26
Svartberg, K., 2006. Breed-typical behaviour in dogs - Historical remnants or recent
559
constructs? Applied Animal Behaviour Science 96, 293-313.
560
Templeton, J.W., Stewart, A.P., Fletcher, W.S., 1977. Coat color genetics in Labrador
561
Retriever. Journal of Heredity 68, 134-136.
562
Tobler, M., Sandell, M.I., 2007. Yolk testosterone modulates persistence of neophobic
563
responses in adult zebra finches, Taeniopygia guttata. Hormones and Behavior 52, 640-645.
564
van den Berg, L., Schilder, M.B.H., Knol, B.W., 2003. Behavior genetics of canine
565
aggression: Behavioral phenotyping of golden retrievers by means of an aggression test.
566
Behavior Genetics 33, 469-483.
567
Wilsson, E. and Sundgren P-E., 1997. The use of a behaviour test for the selection of dogs
568
for service and breeding, I: Method of testing and evaluating test results in the adult dog,
569
demands on different kinds of service dogs, sex and breed differences. Applied Animal
570
Behaviour Science 53: 279-295.
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582
Figure legends
583
Figure 1: Scatterplot of PC1 vs PC2 for C-BARQ responses. The different symbols refer to
584
the sections within C-BARQ (1: Training and obedience; 2: Aggression; 3: Fear and
585
anxiety; 4: Separation-related behavior; 5: Excitability; 6: Attachment and attention-
586
seeking; 7: Miscellaneous; Hsu & Serpell, 2003; http://vetapps.vet.upenn.edu/cbarq/).
587
588
Figure 2: Adjusted means for the three Working Status categories (Gundog, Pet, Showdog)
589
for the 12 personality traits described in the text (Agitated when Ignored, Attention
590
Seeking, Barking Tendency, Excitability, Fetching, Human and Object Fear, Noise Fear,
591
Non-Owner Aggression, Owner Aggression, Separation Anxiety, Trainability, and Unusual
592
Behaviour).
593
594
Figure 3: Adjusted means for the four gender/neuter status categories (EF=entire female;
595
EM=entire male; NF=neutered female; NM=neutered male) for the 12 personality traits
596
described in the text (Agitated when Ignored, Attention Seeking, Barking Tendency,
597
Excitability, Fetching, Human and Object Fear, Noise Fear, Non-Owner Aggression,
598
Owner Aggression, Separation Anxiety, Trainability, and Unusual Behaviour).
599
600

28
Figure 1
601
0.20.10.0-0.1-0.2
0.20
0.15
0.10
0.05
0.00
-0.05
-0.10
PC2
PC1
1
2
3
4
5
6
7
602
603
604

29
Figure 2
605
606
607
608
609

30
Figure 3
610
611