ANSC 415 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

How Else Could Genes Affect Behavior?

• perception — vision, olfaction, auditory

• health, structural differences

Clues that Behavior May have a Genetic Basis

• domestication — breeding for tameness brings along other changes (Belyaev Experiment)

• breed differences in behaviors

• breed predilections for behavioral problems

Clues from Other Species that there are Genetically Based Behaviors

• mouse and rat studies — aggression, freeze, etc.

• familial predispositions — autism spectrum disorder (ASD), obsessive compulsive disorder (OCD), and schizophrenia in humans, addiction (ex.- alcoholism)

• “friendliness mutations” (genetic disruption to DNA)

  • Williams (Beuren Syndrome in Humans) — friendliness, increased empathy, highly developed language skills, cognitive disorders

  • Similar genetic variation in dogs compared to wolves (Bridgett VonHoldt)

Feline Behavioral Genetic Examples

• treatment (boldness) in cats — linked to sire

• Do You Think Coat Color in Cats is Related to Temperament?

  • No

Breed Specific Behaviors in Cats

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

• vocalization in siamese cats?

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

Nervous Pointers

• highly inbred line of pointers — 1960’s from a single pair

• two lines — “Stable Strain” (A) and “Nervous Strain” (E)

• ~80% of E dogs are pathological

• nervous strain characterized by excessive timidity, hyper-startle reflex, decreased exploratory reflex, rigid mobility — in presence of humans

• highly studies — 60’s to early 90’s

What Else Would You Want to Know About These Dogs and How They Develop?

• Are they normal with other dogs?

• Are there any other non-behavioral characteristics?

  • marked bradycardia

  • congenital deafness - peripheral

• How are they raised?

  • effect of maternal caregiving? — cross-fostering doesn’t affect behavior development

  • effect of environment/socialization/early handling

OCD (Compulsive) Behaviors

• are characterized by stereotypical behaviors

• repetitive, constant, serve no apparent purpose

• often brought on by stress, conflict

• some breed specific

• must be differentiated from seizures

• bull terrier tail chasing

• doberman sucking on blanket

• fly biting/fly snapping — CKCS, Bernese Mt. Dog

Spady & 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”

• 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

Mechanisms for Generating Variation

• faster evolution of microsatellite repeats

  • = more alleles available for selection

  • ex.- for neurotransmitters, receptors, ion channels, synaptic vesicle protein, etc.

    • SINE (small interspersed nuclear elements)

      • placement could affect gene expression

      • ex.- canine narcolepsy, centronuclear myopathy in labs, merie coat coloring in several breeds

Narcolepsy in Dogs

• inserting of a canine-specific SINE — discovered at Stanford 1999 (dog genome mapping complete in 2001)

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

How Do you Describe or Quantify the Behaviors Themselves?

• test battery

• owner-directed survey

• expert-rating approach

• observational test

Is Aggression Genetic? Are there Breed Differences in the Incidence of Aggression?

• study published in 2008 — Duffy, Hsu, Serpell

• surveyed owners of dogs using C-BARQ (Canine Behavioral Assessment and Research Questionnaire)

• Scales of 0-4 (0= none, 4=serious)

Stranger Directed Aggression

Dach, Chih, Doberman, Rott, Yorkie, Poodle

Owner-Directed Aggression

generally low but Basset Hound, Beagle, Chih, Am cocker, Dach, EngSS, JRT

Dog-Directed Aggression

Akita, Boxer, Australian Cattle dog, German Shepherd, Pitbull, Chih, Dach, Eng Springer Spaniel, JRT, Westie

Aggression & Fear Interaction

Dach, Chihu, Yorkies

Behavior Research Methodologies

• qualitative vs. quantitative

• observational vs. experimental

Possible Comparisons

• comparing between species

• comparing between breeds

• comparing between genders, ages, etc.

Procedural Issues

• effect of observer on behavior

• effect of humans handlers

  • social interaction

  • “Clever Hans” effect (observer-expectancy)

• location?

• time?

• videotape vs. live?

• anthropomorphism

• ethics

Owner-Directed Surveys, Questionnaires

• difficult to develop scales

• ex.- C-BARQ

• sampling issues

• causality issues

• owner biases

• folk knowledge

Biological Measures

• measures of sympathetic nervous system action

• measures of adrenal activity

• measures of immune activity

• measures of other hormonal activity

• measures of neural activity

• measures of genetic similarity/diversity

Issues with Biomarkers

• sampling

• timing — natural rhythms

• processing

• measurement

• analysis

• interpretation

Validity of Research

• Internal Validity: the measurement means what you think it means

• External Validity: the obtained results can be generalized to a larger population