1 / 23

Proximate causes

Proximate causes. Interaction among gene/environment/ development persist and change over entire lifetime of animal We’re simplifying by focusing the “straight line” interactions for now. Behavioral Genetics. Single gene effect - Drosophila sp. V T = V G + V E + V I V I = V G x V E

january
Download Presentation

Proximate causes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Proximate causes • Interaction among gene/environment/ development persist and change over entire lifetime of animal • We’re simplifying by focusing the “straight line” interactions for now

  2. Behavioral Genetics • Single gene effect - Drosophila sp. • VT = VG + VE + VI • VI = VG x VE • Inbreeding - homogeneous strain - e.g. rearing condition (VG = 0, VT = VE) • Strain difference (VE = 0, VT = VG )

  3. Hybridization - love birds, hygienic vs. unhygienic bees, cricket song • Cross-fostering - e.g. cockatoo-reared galah • galah begging call, alarm call, • cockatoo contact call, slow wingbeat, food

  4. Heritability • Degree of genetic determination ratio of genetic variation in a behavior trait • GD = VG /( VG + VE + VI) • Cross inbred strains and measure behavioral variation

  5. VE = (112 + 418 + 325)/3 = 285 • VG = 465-285 = 180 • GD = VG / VT = 180/465 = 0.39

  6. Realized heritability, hr2 : a measure of the response of a trait to selection • Measure differences in behavioral traits between base stock and selected breeding parents (S), and between base stock and offspring (R) • Selection differential, S • Response to selection, R • hr2 =R/S

  7. TREES 6(8): 254-262, 1991 • Genetic control of migratory behavior • When to migrate? Migratory pop. x Resident pop. => 40% of F1 migratory The migratory restlessness may change by selective breeding

  8. How far? ---Long distance x Short distance => intermediate distance • What direction? ---Resident x Exclusive migrant =>F1 migrant w/ parent direction ---SE migrant x SW migrant =>intermediate ---Species change direction during migration. Captive ones show same behavior

  9. Other migratory traits: ---morphological features ---seasonal change in feeding rate, food and habit preference, activity pattern

  10. Group size preference • Proc. Nat. Acad. Sci. USA 97: 14825-14830 • Parent – offspring regression • Group size of individual cliff swallow (Petrochelidonpyrrhonota) ~ parents • Foster-raring individual ~ biological parents

  11. Naive animal - e.g. garter snakes and slug Mutation • Twin studies • identical (monozygotic) twins • fraternal (dizygotic) twins • Mosaic • Quantitative Trait Locus Analysis (QLT)

  12. Towards behavioral genomics Science 291: 1232-1233, 2001 • Single genes do not determine most human behavior • Nearly all behaviors that have been studied showed moderate to high heritability • Environmental factors make people different from, rather than similar to, their relatives

  13. Information and techniques generated by the human genome sequence will help locate and identify genes involved in behavior • Problems • Detect genes of a linkage with large enough effects • Most valid diagnostic schemes for genetic research

  14. A greatly improved map of human genome sequence helps improve allelic association studies to locate QTLs • To ID the effects of QTLs • Bottom-up: functional genomics and proteomics • Top-down: behavioral genomics • Genome sequences of other organisms

  15. Future perspectives • Understanding the neurobiological basis of individual (behavioral) differences and a better grasp of the etiology of diseases • Discovery of new and more specific drug treatments • Limitation • Gene-environment interplay • Distribution of effective sizes of QTLs

  16. Molecular techniques • Transgenic • Knockout • Gene mapping and association • Protein electrophoresis • DNA fingerprinting

  17. Per gene and song pattern • Observation – • In both D. melanogaster and D. simulans wildtypes, difference in per alleles ~ differences in male songs (pleiotropy). • Wildtype per alleles differ in different species • Hypothesis – Intraspecific differences in song are caused by differences in the per alleles

  18. Building a brainier mouse(Sci. Am. 42-48, 2000) • Molecular basis of learning and memory • Hebb’s learning rule – a memory is produced when 2 connected neurons are active simultaneously in a way that strengthens the synapse • LTP – Long-term potentiation vs. LTD – Long-term depression of synaptic connection in hippocampus

  19. NMDA receptors require 2 signals: binding of neurotransmitter glutamate, membrane depolarization • Dumb mouse – NMDA lack NR1 subunit in CA1 region, impairment in spatial memory and other task • Young animals produce NR2B, old animals more NR2A in NMDA, NR2B stays longer than NR2A

  20. Smart mouse – extra copies of NR2B • Test 1. Recognition of objects: smart mice explore only new objects, normal mice explore both old & new, remember objects 4~5 times longer • Test 2. Remember fear longer • Test 3. Fear extinction learning faster

  21. Test 4. Morris water maze, finding submerged platform in milky water – need analytical skill, learning and memory, ability to form strategies • Learning and memory enhance problem-solving, but intelligence has many aspects

More Related