Chapter 4: Molecular Genetics and Development
Chapter 4: Molecular Genetics and Development BIOL 515
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This 3 page Study Guide was uploaded by Erica Leonard on Monday December 14, 2015. The Study Guide belongs to BIOL 515 at Kansas State University taught by Eva A Horne in Summer 2015. Since its upload, it has received 17 views. For similar materials see Behavioral Ecology in Biology at Kansas State University.
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Date Created: 12/14/15
Chapter 4: Molecular Genetics and Development Categories of genes Structural genes o Code for RNA, code for proteins o Variety of structures, chemicals, and effects Regulatory genes o Code for RNA, turns on/off other genes o Control expression of other genes o Example: hunting sequence can be altered by selection for regulatory genes turning off the grab-bite and kill-bite Gene’s effect on traits Single gene vs polygene o Polygene- 2 or more genes effecting same trait o Locus- location of gene on chromosome o Pleiotropic effects- 1 gene effecting multiple traits o Epistasis- effect of one gene is modified by another Determining a genetic basis for behavior Artificial selection- select individuals with desired behavior & mate them Study of single gene effects on behavior Inbreeding- mating related to individuals – reduces genetic variability by reducing heterozygosity (decreases 25% with each generation of sibling mating; identical in 98% of genes o Strain 1 and 2 raised in identical environments different behavior = genetic control o Strain 1 raised in 2 different environments different behavior = environmental control o Role of environment (reciprocal cross)- genetically identical; raised by different mothers Act same environment has little effect; genetic control Act different environment has large effect; environmental control o Cross fostering = offspring from 1 strain raised from birth by female of another Act like genetic strain environment after birth had little effect Hybridization- cross individuals with different types of same behavior o Foraging behavior of fruit flies Rovers- move more, favored when population densities are high Sitter- move little, use less energy, favored when population densities are low Single gene mutation Change in DNA bases that cause different protein to be constructed by 1 allele of a gene o Expose population to mutagen; choose animals with behavior change; determine if change occurred in anatomy or physiology; conduct breeding experiments to determine if change was caused by a single gene Mutation & mosaic analysis Analysis of animals made up of parts of different individuals- tissues from wild type & from mutant animals (mix cells from 2 different zygote into 1) Which gene controls a behavior? Behavior candidate alter gene expression (knock in, knock out, RNA interference) Knock in- add extra copies of a particular gene Knock out- inactivate a particular gene RNA interference- inactivate the mRNA of a gene by injecting a matching double stranded RNA (found in immune system to inactivate viral RNA) o Blue rose= put RNA interference in red rose, knock out gene for red, knock in gene for blue Gene function in behavior Code for different structural proteins so body functions differently & leads to different behaviors Microsatellite- repeating units in chromosomes used to separate individuals & species; codes for receptors for vasopressin & how many are made Methods for the study of polygene effects on behavior Quantitative trait locus- chromosome region containing at least 1 gene that contributes to variation in a quantitative trait QTL mapping- links phenotypic and genotypic data; identify action, interaction, number & precise location of these regions Crossing over in meiosis leads to chromosome breaking up and mixing to get both colors Gene networking= patterns of how genes work together for normal function of an organism Social bonding in female mice (each step requiring a gene) o Estrogen released binds to receptors in amygdala and hypothalamus prod of oxytocin in hypothalamus & activation of oxytocin receptors in amygdala is triggered oxytocin binds to receptors triggering multiple behavioral Effects of social environment Brightly colored aggressive fish is dominant, dull colored nonaggressive fish is subordinate Dominant male is removed from the fish tank once subordinate male notices changes to bright colors immediately take on the role as the dominant male within minutes Epigenetics Heritable changes in gene expression not encoded by DNA (nucleotides) Modifications include: methylation, acetylation, & phosphorylation Can result in alternation of gene expression patterns Mother/ pup contact in rats triggers 2 changes o Increases glucocorticoid (stress reducer hormone) receptor in hippocampus o Increases estrogen (maternal behaviors) receptors in hypothalamus Genetic effects Complex relationships connect genes, brain & social behavior Physiological time- fast effects on brain activity (mins/hrs) Developmental time- show effects on brain development & genome modification (over lifespan) Evolutionary time- natural selection (yrs/decades) Causes of behavioral change during development 1. Nervous system a. Wiring develops, behavior or movement occurs, neural circuitry disappears b. Example: chicken develop circuitry to control hating behaviors and never lose that ability 2. Non-neural morphology a. Paddlefish larvae eat zooplankton, develop gill rakers, adults filter feed 3. Hormonal state a. Age polyethism- change in frequency of behavior with age; regulated by juvenile hormone; common in insects for behavior regulation 4. Physical environment a. Sex determination- early embryos are indifferent gonads capable of becoming testes or ovaries b. incubation temperature determines sex and results in brain structure changes, hormone production changes, and different behaviors c. Prefer opposite temperature than what they were incubated in because they prefer to breed from a different clutch, less homozygous breeding, better chance of survival for offspring and no inbreeding (larger gene pool) Sensitive period Time in development during which some change occurs allowing different behaviors o Differs in duration among species, individuals, and functional systems o Influenced by environmental stimuli, stable Song development in zebra finches Male has courtship song and large song system Females have no estrogen smaller song system Babies can’t sing at birth so they listen and learn model song, begin subsong after 150 days, begin full song after 200 days If baby is isolated hears no song no model to remember adult song doesn’t match normal song If baby is deafened learns song remembers model adult song is less like original song; know what song should sound like but can’t hear their notes to make needed adjustments Song development with no early species specific experience- brown headed cowbird Eggs are laid in separate species nest; raised by a different species Raised with other species, song, and parental care Expected to know own species song when reunited with birth colony A species needs to able to modify their song in order to still be successful in mating in new habitat in case they end up in wrong location
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