Genes and Behavior

1. Genes and Behavior Animal Models

2. Behavior is a complex phenotype • Mating; territory defense; aggression; social interactions • Great deal of natural variation • Behavior can depend on age, previous experiences, sex of the organism, rank in a social system, etc. • Environmental effects • Can genes contribute to this variation? Can genes “determine” behavior?

3. Approaches to Studying Behavior • Proximate causes of behavior • “How” questions • Generally deal with mechanistic causes of behavior • Ultimate causes of behavior • “Why” questions • Generally deal with evolutionary causes of behavior

4. Study of Genes and Behavior • Does a gene cause behavior? • No. A gene creates messenger RNA and proteins. These, along with complex interactions between other genes and environments, can alter behavior. • Examining genetic underpinnings of behavior • Keep environment as homogenous (similar) is possible

5. Approaches to studying genes and behavior • Quantitative approaches • Using many markers (quantitative trait loci) throughout genome to identify chromosome region(s) that correlate with behavior. • Single gene approaches • Forward Genetics: Mutate genome at random, screen for behavioral differences, pinpoint which gene has been altered • Reverse Genetics: Take gene of interest, mutate it specifically, examine behavioral changes

6. Courtship song and the period gene • Male fruit flies (Drosophila) have complex courtship behavior • One behavior: wing vibration (love song)

7. IPI (ms) (Kyriacou and Hall 1986) Courtship song and the period gene • Male courtship song can differ in the interpulse interval (IPI) between pulses • Species specific differences • melanogaster: Avg. IPI 30-40 ms • simulans: Avg IPI 45-55 ms

8. Courtship song and the period gene • Scientists discovered that when they transferred a small piece of the period gene from D. simulansto D. melanogaster, the melanogaster males began singing the simulans song.

9. fruitless • Male fruit flies court male flies and females indiscriminately • No human version of the gene. • More than 10 genes involved in sexual orientation of fruit fly. • video

10. Voles: Monogamy v. Promiscuity Montane Vole Prairie Vole Fewer than 5% of mammals are habitually monogamous. Prairie voles (Microtusochrogaster) are among the select few.

11. Voles: Monogamy v. Promiscuity

12. Behavioral Genetics • Prairie voles are monogamous • Montane voles mate and do not work together to raise young • Different response to oxytocin and vasopressin • Peptide receptors different

13. Voles: Monogamy v. Promiscuity Genes were sequenced, slight difference in sequence of prairie vole due to increase in repetitive region upstream of coding region. Montane Prairie (Young et. al. 1999)

14. Behavioral Genetics (Cont.)

15. Behavioral Genetics • Mice: fosB gene • Determines whether female mice nurture their young • Both fosB alleles disabled: ignore young • Normal mothers: protective maternal behavior • Protein expressed by fosB activates other enzymes and genes that affect neural circuitry within the hypothalamus

16. Behavioral Genetics • fosB present: mother cares for her young • fosB absent: young are ignored and eventually die

17. Other Mice Models • pet-1 • aggressive mice • unc-79 • alcoholic • Lynx2 • anxious mice