It would be fair to say that the pioneering studies conducted by Scott and Fuller using dogs in the 1950s and 1960s gave birth to the modern scientific discipline of behavioral genetics. It has only been in the last decade, however, that dogs have again caught the interest of biologists interested in the evolution and domestication of dogs, and once again research on dogs is pushing forward the fields of animal behavior and cognition.

With the availability of affordable DNA analysis that can provide information about hundreds of thousands - or even millions - of markers, we have started to look for the genetic basis of behavior at the level of the gene. A few genes have been identified that are associated with specific behavioral traits in dogs, like xxxxxxxx (Bridgett). There is also a growing number of studies that looked for the genetic basis of behavioral differences in dog. But as I explained in an earlier post, the associations of behavior with genes have been generally weak and not especially useful for identifying genes of major effect or improving traits through genomic selection. 

A new study, however, is a game-changer (MacLean et al 2019). It has been made available before submission for publication, so it has not been subject to peer review and you should keep that in mind. But what it offers is a tantalizing first look at links between genes and behavior in dogs. 

Previous studies have looked for variation in genes that could account for differences in behavior in a group of dogs. The strength of the association between genetics and a trait is indicated by a statistic called "heritability", and in most studies of behavioral traits in dogs of a particular breed, the heritability was found to be low; i.e., variations in behavior were not associated with genetics.

Instead of focusing on a particular breed, the new study looked for major differences in behavior and genetics across many breeds. And here, they were successful.

In this study, a large set of behavioral assessments from CBARQ testing of > 17,000 dogs was paired with DNA genotyping data for > 5,600 dogs of 141 breeds  by combining information from two separate studies (Hayward et al. and Parker et al.) that used the current gold-standard analysis platform (high density SNP markers; > 100,000). They identified 14 behavioral traits of interest and looked for differences in the behavior of breeds that appeared to be associated with differences in the DNA, which would tell them the heritability of these specific traits.

​What they found was fascinating.

In this graph, the behaviors they looked at are indicated down the y-axis, and the strength of the association between genetics and the trait, i.e., heritability, is on the x-axis. The stronger the association, the higher the heritability. The grey dogs are measurements of heritability made on dogs of the same breed. The green and yellow dogs display heritability of those same traits when the associations are made looking across breeds.

You can see here that heritabilities determined from dogs of the same breed are generally low, less than about 0.3, which means that 30% or less of the variations in behavior can be attributed to variations in genotype.

But when you compare across breeds, the average heritabilities are high, from about 0.4 (40% of variation explained) to more than 0.7 (70% of variation explained.

This is very exciting, because it's the first time we have been able to detect strong links between genes and behavior. 

This is a game-changer. Our understanding of the genetic basis of behavior in dogs has gone molecular.

We now have large databases for both behavior and genotype, and these will continue to grow in size because the methodology for both is standardized (CBARQ for behavior and high-density SNP for genotype). These allow us to do analyses like the one below, which is a "heat map" that depicts the behavioral scores by breed displayed along with the dendrogram displaying their genetic relatedness. You can easily find the sporting dogs because they are high in trainability, and the small breeds like the chihuahua, rat terrier, and miniature pinscher stand out for scoring  high in traits that we might describe as reactive or "fiesty" (e.g., aggression, fear). The herding breeds score high in trainability while the hounds are low. And now we are finally able to explore the genetic basis for major breed-specific differences in behavioral traits among dog breeds. 
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This paper will need to go through peer review, revision if necessary, then publication, so don't expect to see the final version for at least a few months. But I suspect we're about to see a flood of studies that also leverage the large datasets now available for both behavior and genetics. Buckle up!

NOTE: If you are interested in the links between genetics and behavior, now is the time to start boning up on the jargon and concepts you need to understand these studies. You can find relevant articles in the blog posts on the ICB website (just search for a topic or keyword). Even better, ICB has courses designed for dog people with no background in science that will get you up to speed. This genie is out of the bottle. A little homework now to learn the basics will pay off every time you read about an exciting new paper about the genetics of behavior in dogs!

Wow. What on earth is that?

This is not a paper about behavior. It is about measuring something called heritability (h ^2). Here's the translation of that first equation:

Heritability is the fraction of the variation in a trait that can be attributed to variation in genetics.

This study shows that there is a measurable fraction of the variation in a number of behavioral traits in dogs that is due to genetics. 

Heritability doesn't mean "inherited". It doesn't tell you how much variation there is in a trait. It doesn't tell you how likely a dog is to inherit a behavior. None of those things.

Clearly, to understand this paper, you need to be really clear on the meaning of heritability. You can start learning about it by reading some of my blogs on the ICB website, starting with this one:

                Understanding the heritability of behavior in dogs             

There are others if you do a search.

Also, please consider taking the Genetics of Behavior course. We will go through some papers like this one (including this one!) so you have a good understanding of what the information does - and doesn't - mean. There will be more studies like this one. Make sure you get the most out of them by understanding the science.

Check out those blog posts, and consider taking my course that starts (coincidentally) next week, 4 March 2019:

REFERENCES

MacLean EL, N Snyder-Mackler, BM vonHoldt, & JA Serpell. (unpub) Highly heritable and functionally relevant breed differences in dog behavior. BioRxiv preprint accessed 27 February 2019.. doi: http://dx.doi.org/10.1101/509315.

Dealing with the behavioral issues of dogs is a big business. Trainers and therapists abound, as do the professional suffixes tagged after the names of those who took some sort of course or were accredited by an organization.

I have no idea whether the majority of these people know what they're doing. I can tell you, though, that the scientific literature about behavior in dogs is a morass of tangled, insufficient, and often contradictory studies. In fact, in the field of canine behavior, science is marching forward very slowly, even as the ranks of lay behaviorists swell and practitioners claim to become ever more authoritative and confident of their expertise.

How reliable are behavioral assessments of dogs? Are they repeatable, meaningful, and verifiable? This especially matters when dogs are being assessed for working ability, as in breeding programs for service, police, and other types of working dogs. Breeding and training these dogs is time consuming and expensive, and being able to accurately assess the usefulness of a potential working animal is the differences between success and failure.

A recent study evaluated the reliability and validity of various behavioral tests that are used to assess the traits of working dogs (Brady et al 2018). What the researchers found should give pause to anybody that professes to have a deep and true understanding of canine behavior. 

For the selected studies, they evaluated the reliability, repeatability, and predictive validity of the behavioral tests,  both within and among "raters" (the individuals conducting the evaluation). They had an assortment of problems to deal with, like the use of different terminology for the same trait. More seriously, they found that data were often inadequately reported, statistical analyses were misinterpreted, and there was an overall lack of concordance in the various methods used for assessment.

​Ultimately, they concluded that there is "a widespread lack of information relating to the reliability and validity of measures to assess behaviour and inconsistencies in terminologies, study parameters and indices of success...This review indicates that we are still not addressing concerns over the lack of standardisation (sic) amongst research on dog behavioural tests". 

What this means is that we are probably not as good at assessing behavioral traits as we think we are or, at the very least, it's hard to tell how good we are because of limitations of the studies and the lack of standardization in terminology and protocol. Certainly, it should give pause to anybody relying on "experts" for advice, most of whom cannot lean on published studies to support claims about the validity and reliability of their assessments.

Buyer beware.

You can download a copy of the study below.

REFERENCES

Brady, K., N. Cracknell, H. Zulch, and D.S. Mills. 2018. A systematic review of the reliability and validity of behavioural tests used to assess behavioural characteristics important in working dogs. Frontiers in Veterinary Science 5(103);doi: 10.3389/fvets.2018.00103.

By Carol Beuchat PhD
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Have you ever wondered how scientists figure out the genetic basis of a particular trait? This is especially difficult if the trait is polygenic and many genes plus environmental effects might be involved.

These are called "continuous" or quantitative traits; most of the traits under selection by dog breeders are of this type. For most of us, the process of identifying the markers associated with particular traits is a "black box" from which information mysteriously emerges from huge files of cryptic genotype data. How are scientists able to identify which of the many of thousands of markers play a role in the expression of a specific trait? ​​

In ICB's has a new course, The Genetics of Continuous Traits, we'll take the lid off the box and show you how scientists get from genotype to phenotype using DNA data you provide for your own dogs! For a learning example, we will study the genetics of body size, which is a trait that varies widely and continuously among breeds and mixed-breed dogs.

​We will use the raw DNA data file provided by Embark for your own dog, together with information about the size of your dog that you will provide. If we get data for enough dogs of a single breed, we can also explore the genetic basis of variation within a breed, also for a variety of mixed-breed dogs.

We will review some published studies for comparison with our own results, so you will also get to make comparisons with "real world" information.

This course is a great opportunity for you explore "under the hood" and learn how scientists go from a table of data to new information extracted from the data for your own dog!

Don't miss this great learning opportunity and the chance to analyze the data for your dog!

This unique online course is $125 and lasts 10 weeks, with students free to work along with the class or at their own pace. There are no prerequisites and a scientific background is not required - just your keen interest in dogs!

Class starts 11 February. Register now to join us!
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