5 replies to this topic

[kelpiegirl]

A handful of genes could mark the difference between high-strung Chihuahuas and unflappable basset hounds. A comparison of 148 dog breeds has uncovered genes for size, lifespan, and even complex behaviours such as pointing and herding.

Geneticists have previously uncovered genes for dog traits such as coat colour and narcolepsy, but these searches tended to focus on a single breed, comparing pooches with variations in a single trait – for example, boxers with and without white spots.

This strategy does not work for rooting out the genetic basis of behaviours because certain breeds either display these behaviours or they don't, says Gordon Lark at the University of Utah in Salt Lake City, US.

So with the help of a dog show judge, Lark's team scored dogs from 148 breeds for traits including herding, pointing, boldness, excitability and trainability. Then they scoured their genomes for similarities and differences. Dogs were also scored for size, body proportions and longevity.

The search implicated several genes in stereotypical dog behaviours. For example, herding behaviour typical of collies and shepherds may be linked to a gene that is similar to one associated with schizophrenia in humans.
Excitability gene?

Also, a gene involved in processing the neurotransmitter dopamine may explain both the boldness of rottweilers and the timidity of pugs, while a gene for brain development appears linked to pointing in dogs such as Irish setters.

And though dogs both large and small showed a genetic basis for boldness, only the little dogs possess the genetic markers associated with excitability.

Lark's approach worked even better for less subjective qualities, such as size and longevity. His team confirmed a smattering of genes linked with size that had been revealed by previous studies.

Greg Barsh of Stanford University in California, US, says the research certainly pushes forward the genetic analysis of dog personalities, but he cautions that behaviours may be difficult to explain genetically.

"We've learned from human genetics that classifying behaviour is not so easy," he says. Just as one person's schizophrenia differs from another's, collies might herd differently than sheepdogs.

Journal reference: Genetics (DOI:10.1534/genetics.108.087866)

[Smokjbc]

We've learned from human genetics that classifying behaviour is not so easy," he says. Just as one person's schizophrenia differs from another's, collies might herd differently than sheepdogs.>>>


Interesting piece.. did anyone else see the irony in this statement ?

[kelpiegirl]

[SoloRiver]

For this paper, they asked a show judge to score all the breeds for a number of behavioral characteristics. "Herding" was scored as a binary trait (present/absent) and all the herding breed dogs were scored the same way.

SNP Based Association Mapping of Dog Stereotypes
Paul Jones*, Kevin Chase†, Alan Martin*, Elaine A. Ostrander†† and Karl G. Lark†1
Genetics 2008

Abstract
Phenotypic stereotypes are traits, many of which are polygenic that have been stringently
selected to conform to specific criteria. In dogs, C, familiaris, stereotypes result from breed
standards set for conformation, performance (behaviors), etc. As a consequence, phenotypic
values measured on a few individuals are representative of the breed stereotype. We used DNA
samples isolated from 148 dog breeds to associate SNP markers with breed stereotypes. Using
size as a trait to test the method, we identified six significant loci (QTLs) on five chromosomes,
implicating candidate genes appropriate to regulation of size (e.g. IGF1, IGF2BP2 SMAD2 etc.).
Analysis of other morphological stereotypes, also under extreme selection, identified many
additional significant loci. Less well documented data for behavioral stereotypes tentatively
identified loci for herding, pointing, boldness and trainability. Four significant loci were
identified for longevity, a breed characteristic not under direct selection, but inversely correlated
with breed size. The strengths and limitations of the approach are discussed as well as its
potential to identify loci regulating the within-breed incidence of specific polygenic diseases.

[Sue R]

Melanie - Are you saying that a show (conformation) judge was asked to "score" by breed (not any particular individuals, demonstrating any particular traits)? For instance, a breed in the herding group was simply given a score of "present" for "herding", only because it was a member of the herding group, regardless of whether or not that particular breed (or any individuals within it) actually demonstrate any worthwhile inherent stockworking abilities in the present-day population?

Phenotypic stereotypes are traits, many of which are polygenic that have been stringently
selected to conform to specific criteria.

How can someone say that herding is "present" when the general population (of non-worling-bred Border Collies, since it is a show judge that did the evaluation) has not been stringently selected for some generations (in general) for anything to do with stockworking ability? In the show Border Collie, the only thing that has been stringently selected for has been appearance, which is the same thing that all conformation-bred dogs have been selected for.

If they considered this a "complex behavior" then how could they make a simple judgement of present or absent without any way of evaluating the breed as a whole or individuals as possessing any significant/useful level of the contributing behaviors that comprise such a complex behavior?

[Barb Scott]

I've never heard that Pugs were timid; they seem to poke out their eyes alot and breathe funny, but I'd never call them timid. I think this researcher needs to go back to the drawing board.
Barb S