Behavioral Genetics

How could genes affect behavior?

• encoding neurotransmitters and receptors, ion channels, synaptic vesicle proteins, axon-guidance molecules

• vasopressin, dopamine, serotonin receptor function and number

• perception - vision, olfaction, auditory

• health, structural differences

• importance of behavior and gene-environment interactions

Clues that imply genetic based behavior

• domestication - breeding for tameness brings along other changes (Belyaev experiment)

• breed specific behaviors

  • breed differences in behavior

  • breed predilections for behavioral problems

• familial predispositions for certain disorders in humans - autism spectrum disorder, OCD, schizophrenia, addiction

• friendliness mutations in humans (genetic disruptions to DNA)

  • William-Beuren Syndrome in humans - friendliness, increased empathy, highly developed language skills, cognitive disorders

• temperament in cats being linked to sires

Is coat color in cats related to temperament?

No, studies have shown that coat color is not related to temperament. Public perception has perpetuated this idea.

Examples of breed specific behavior in cats

• wool-chewing is more common in Siamese cats and other oriental breeds

• Persian cats are more likely to be presented for house-soiling, half as likely to be presented for aggression (UK study)

Genetics and social behavior research by Scott and Fuller

• measured reactivity, trainability, and problem-solving in five different breeds and crosses (Basenji, Beagle, Cocker Spaniel, Sheltie, Wire-haired fox terrier)

• found reproducible and measurable differences

• tested further cross-bred generations

Narcolepsy in dogs

• insertion of canine specific SINE discovered at Stanford in 1999

• defective gene that should code for a protein that receives signals to other cells

• behavioral abnormal change with clear physiological background

Nervous pointers

• experiment in the 1960s with a highly inbred line of pointer

• two lines - Stable Strain A and Nervous Strain E

• around 80% of E dogs are pathologically abnormal

• nervous strain characterized by excessive timidity, hyper-startle reflex, decreased exploratory reflex, rigid mobility - in presence of humans (acted normal around other dogs)

• things to consider

  • socialization status of the dogs

  • was this a learned behavior from other dogs?

  • any non-behavioral characteristics? (found to have bradycardia and congenital deafness)

  • how were they raised?

OCD behaviors

• behaviors that are characterized by stereotypical actions

  • repetitive, constant, and serve no apparent purpose

• often brought on by stress, or conflict

• some behaviors are breed specific

• must be differentiated from seizures

• in dogs, it’s termed compulsive behaviors → “obsessive” behaviors are more reserved for people and the mentality behind their actions

• ex.

  • tail chasing in bull terriers

  • blanket sucking in Doberman Pinschers

  • “fly biting/snapping” in Bernese Mountain Dogs and Cavalier King Charles Spaniels

Aggression study

• study published in 2008 by Duffy, Hsu, and Serpell

• surveyed owners of dogs using C-BARQ (canine behavioral assessment and research questionnaire)

• scale of 0-4 (0=none, 4=serious)

• owner direct aggression was generally low, so was stranger directed aggression

• dog-directed aggression was variable by breed, but generally higher than it was to people

Current research on behavioral genetics

• Canine Behavioral Genetics: Pointing out the Phenotypes and Herding up the Genes: Spady and Ostrander

  • hypothesis:

    • some canine behaviors are controlled by a relatively small number of genes

    • “can unravel the genetic basis of both simple and complex canine behaviors with currently available tools”

• Darwin’s Ark

• Embark

• Many Dogs Project

• Penn Vet Working Dog Center

Mechanisms for generating variation in behavior

• faster evolution of microsatellite repeats

  • more alleles available for selection

    • e.g. for neurotransmitters, receptors, ion channels, synaptic vesicle proteins, etc.

  • small interspersed nuclear elements

    • placement can affect gene expression

Behavioral phenotyping

• how are certain behaviors described or quantified?

  • test battery (putting the dogs in certain scenarios, i.e. cognitive testing)

  • owner-directed survey (asking the owner what behaviors they see out of their dog; can include bias)

  • expert-rating approach (vets, professional trainers, kennel-owners, etc.; dogs can act differently around these people than their owners)

  • observational test (observing specific behaviors in natural surroundings)

Behavioral research methodologies

• qualitative vs. quantitative

• observational vs. experimental

Possible comparisons of behavior

• comparing between species

• comparing between breeds

• comparing between genders, age, etc.

Procedural issues when trying to study behavior

• effect of observer on the behavior

• effect of human handlers

  • social interaction

  • “Clever Hans” effect (observer-expectancy)

• location

• time

• videotape vs. live

• anthropomorphism

• ethics

Procedural issues of owner-directed surveys and quistionnaires

• difficult to develop scales

• sampling issues

• causality issues

• owner bias

• folk knowledge

Biological measures of behavior

• measure of sympathetic nervous system (ex. increased HR, dilated pupils)

• measure of adrenal activity (ex. cortisol levels in blood)

• measures of immune activity (ex. antibody and cytokine levels)

• measure of other hormonal activities

• measure of neural activity

• measure of genetic similarity/diversity

• issues with biomarking

  • sampling

  • timing - natural rhythms

  • processing

  • measurement meaning (analysis and interpretation)

Internal validity vs. External validity

• internal validity: the measurement means what you think it means

• external validity: the obtained results can be generalized to a larger population

Why are dogs a good model for human based genetic behavioral research?

• all of the following have been suggested as a reason that the dog may be an ideal system for studying behavioral genetics

  • the domestic dog displays a lot of morphological and behavioral diversity

  • behavioral variation is captured within breeds

  • some behavior disorders of dogs mirror those that are seen in humans