Beahviour Development requires both genes and environment

Transcription

1 Chapter 3 Development is an interaction of genetic with changing external environment o Gene-environmental interaction Interactive theory of development Worker bees o Care of larvae o Construct honeycomb o Regulation of hive temperature o Defense of colony against parasites and predators o Collection of pollen and nectar Worker bees change over time o clean comb cells nurse bee (feeding honey) distributor of food foraging for pollen and nectar genotype: genes, and measurable characteristics : phenotype Whitfield: brain extracts of nurses and foragers to compare gene activity o Different product output of bees o Genetic changes contribute to developmental changes o Microarray slides do not demonstrate that environment is irrelevant Queen bee: pheromone causes changes in brain cells of workers workers produce pheromone that changes gene expression of other workers o Environmental factors are important for gene expression Resultant gene-environment product may play a role in changing the activity of one or more key genes to initiate a series of outputs that alter the development of the brain and behaviour of bee o Juvenile hormone found in nurse workers at low concentration but higher in foragers when young bees are treated with juvenile hormone, they become foragers removal of the corpora allata bee delays its transition to foraging (hormone treatment can switch it back on) Deficits in social encounters with older foragers may stimulate an early developmental transition from nurse to forager o Higher the foragers, the lower proportion of nurse bees that transform Adding young bees have no effect Inhibiting agent is a fatty acid compound called ethyl oleate, which foragers manufacture Nature or Nurture Fallacy DNA in a gene is only expressed when the environment is appropriate o Juvenile hormone, ethyl oleate influence gene activity in bees (eg) Beahviour Development requires both genes and environment

2 Learning: change in animal behaviour linked to experience o Learning requires the use of brain, shaped by gene influence Imprinting: animal s social interaction leads to learning Goslings: imprinted on biologist rather than mother goose o Imprinting does not happen without a prepared brain Cross fostering by tits o Hereditary basis for imprinting was not the same by blue and great tits o Great tits does not mate with own species o Blue tits mate with own Chickadee: remember where they hide food spatial memory o Sherry: place seed in 4-5/72 slots, remove chickadee and reintroduce after removal seed to remove visual or olfactory cues chickadee remembered Clark s nutcracker: impressive memory hides food in big span o Possible rules of thumb: look near little tufts of grass Remember general areas and look at cues o Balda: nutcrackers remember not by cache indicators What causes individuals to develop differently? Members of the same species can differ in behaviour o Alaskan chickadee > Coloardo chickadees at memory Alaskan chickadee have larger hippocampus Environment can affect size of hippocampus Environmental Differences and Behavourial Differences Spiny mouse: huddle together based on associations in early life o Learn distinctive odors of companions Paper wasps: odors as recognition cues o Individuals tolerate each other based on odor of nest o Transferred wasp who acquire odor of nest are not attacked Paper wasps can distinguish by facial features paint altered individuals were subject to more aggression by fellow females Belding ground squirrels: o Siblings reared apart o Siblings reared together o Nonsiblings reared apart o Nonsiblings reared together o Squirrels reared together siblings or not, tolerated each other while those apart were aggressive to each other Olfactory of associated individuals However, biological sisters reared apart engaged in fewer aggressive interactions than nonsiblings Squirrels had some kind of way to recognize siblings

3 o Armpit effect: find what self smell like to recognize others reference against who Mateo: Belding s ground squirrels have scent producing glands near mouth and back sniff oral glands of others o Juvenile offspring investigate plastic cubes that have been rubbed on dorsal glands of other squirrels of varying relatedness Captive squirrels never met relatives, but if they could learn what they smell like, they can find similar scent of relatives Sniffs longer for less familiar relatives Belding squirrels learn what they smell like to use as information to figure out which to mate with and which to ignore or reject Genetic Differences and Behaviourial Differences Blackcaps: winter in south great Britain, some in Africa Berthold: British population birds did not forget how to migrate, but must have originated from somewhere else Migratory behaviour may be hereditary and subject to selection o Breed late migrating birds together = line of late migrators Parteckle: blackbirds: urban male blackbirds develop sedentary habits, while male and female forest birds migrate o Males are bigger than females and overpower females in German winters to monopolize food Hereditary Differences in Food Preferences of Garter Snakes Costal and inland snakes o Inland snake feed on fish and frog in lakes and stream o Coastal snakes eat banana slugs Arnold: reared inland and coastal snakes o Separate young from mother and littermates to remove influences o Offered snakes to eat banana slug costal snakes ate, inland snakes didn t o Took a separate set of snakes and not feed anything Newborn snakes flick tongue at fluids of other species and scent is sent by tongue to vomeronasal organs that detect prey Tongue flicks = responsiveness to food Inland snakes ignore slug odor while coastal respond Genetic differences coastal snake have a different allele o Crossing adults should generate a group of hybrid offspring o Snakes of costal habitat with first ancestor who could derive energy from slugs, then reproductive chance overtime would favour divergence Single Gene Effects on Development

4 Knockout experiments: inactive a given gene to determine the contributions of the gene to a particular environment. o Eg. Mouse with fosb gene retrieve displaced pups o Oxt gene: cannot remember females o Trpc2 gene: male makes love to another male Treats every mouse as a compulatory partner since it cannot figure out scents Vomeronasal organ distinguishes sex identifying scents o Trpc2 gene: females with 2 inoperative copies acted like a male One gene defective doesn t allow it react in the proper manner Drosophila: rovers travel four times farther when feeding than sitters o Rover dominant gene, sitter, recessive o Gene for: codes for a cgmp-dependent protein kinase, and more is produced by rover Humans: lateral frontal cortex human intelligence o Variation lead to variation in brain phenotypes (cognitive abilities) o COMT: encodes for intelligience Serotonin relays messages in neurons, gene on chromosome 17 regulates reuptake of serotonin. o Different people have different amounts of protein, which affect neural activity mood, emotions, anxiety (5-HTT) Lecture 2 Chocolate cake different reciples different taste Behaviour trait variation: discrete (qualitative) and continuous (quantitative) Assessment of behaviour: discrete = population genetics (alleles) o Continuous: quantitative genetics (heritability) H2 = Vg/(Vg + Ve), where h2 is heritability, Vg is variance by genetic influences and Ve is variance by environmental. Genetic basis for behaviour X = genetic variation underlying the trat Tools to study genetic basis o Parent-offspring regression o Pedigree analysis o Twin studies o Hybridization (2 different traits interbreed) o Artificial selection o Adoption/cross fostering studies o Knockout studies o Mutant studies o Gene insertion experiments o Gene product manipulations Discrete variation: tongue rolling, mating behaviour in ruffs o Ruff Pedigree analysis: single polymorphic gene, dominant = satellite

5 Independent, satellite, displaying o Mating in marine isopods Alpha (territorial), beta (mimic), gamma (sneaker) 3 alleles, single polymorphic gene Calling duration in crickets o Long callers, short callers Divergence in selection Nestbuilding in house mice o High gatherers and low gatherers of cotton Divergence in selection Selection of aggression linked to other traits pup retrieval Twin studies o Similarity of monozygotic > similarity of dizygotic for heritability Genetic basis to intelligience o Caveat: are environments really the same? Adoption studies o Offspring and genetic parents Same genes, different environment o Offspring and adoptive parents Different genes, same environment o High heritability if similarity of offspring and parent is high o Caveat: Are adoption environments different? Maternal environment before birth Complex behaviour are h2 = 0.5, 50/50 environment and heritability Eugenics: government imposed selection to change traits o Sterilizing may wipe out other traits o Alberta, then Germany as a tool for Nazis Genetic influence and determinism: politic resistance (variants are heritable) o Wilson: polygamy is innate Behaviour is a continuous interaction of genotype and environment Mutant studies (drosophila) o Lot: elevate salt preference o Cheap date: susceptibility to alcohol o Ether a go go: shake legs when anaesthetized o Stuck: mating males get stuck o Coitus interruptus: copulation is brief o Icebox: females unreceptive to males Fitness effect of rover and sitter o High vs low density o Sitter costly at high density, rover can find food faster o Behaviour can change when environment changes That there is a gene for behaviour X does not mean: o Gene is fully responsible for behaviour X

6 Rover and sitter only behave different when food present o Behaviour X is inevitable Rover will be a sitter if starved prior to food Honey bees: amfor gene leads to a change in roles o cgmp dependent protein kinase (PKG) o level of PKG = different roles higher in foragers bees not an effect of age young foragers have more PKG, and middle aged undertakers and food handlers are high low respectively feed bees PKG becomes forager o Amfor increases phototaxis = leave hives, younger bees remain in hive Amfor = Drosophila for o cgmp dependent protein kinase C elegans foraging and social behaviour o Single amino acid difference in receptor protein o Social and solitary Limbic system reward cascade o Vasopressin in prairie vole for monogamy Not just synthesis but receptor for Reward pathways: dopamine = pleasure o Reward deficiency syndrome A1 = low density of dopamine D2 receptors Less feelings of pleasure from typical activities = predisposition to compulsive behaviours and drugs Less reward from average behaviours A2 = high density of dopamine D2 receptors Substance abuse depends on availibitily of substance and exposure o Could be triggered by stress Evolutionary conservation of behaviour mechanism o Reward cascade: voles and humans o Foraging behaviour (PKG pathways): c elegans, drosophila, bees o Basic structures can arise from same ancestors with descent with modifcations o Common underlying mechanisms can lead to different phenotypic events when environment changes Genes affect nervous system, which affects behaviour, and are plastic and more than one behaviour can be maintained = genetic polymorphism