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28 Cards in this Set
- Front
- Back
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Single gene effects on behaviour |
Relatively rare, but easy to study. e.g., Hygienic and non-hygienic honey bees: American foul brood bacterial disease that attacks bee larvae. In hygienic colonies workers will uncap a cell in the colony if it contains a dead larva or pupa and remove corpse. Non-hygienic colonies workers do not remove corpse |
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Knockout mice |
gene removed or rendered inactive |
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Knockin mice |
novel gene inserted |
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'conditional' mice |
promoter for a gene altered so it can be switched on or off by experimenter |
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What are polygenic effects? |
When a phenotypic characteristic is the result of numerous genes interacting, not just a single gene. |
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Why are polygenic effects hard to study? |
-Many genes may have a small but important effect on phenotype. -Do not follow Mendalian laws of inheritance.
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Pleiotropy |
Allele has more than one effect on phenotype -common b/c change in one enzyme likely to affect several pathways e.g., yellow allele in Drosophilia: slower at mating and yellow stripes on body |
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White haired, blue eyes cats |
Example of Pleiotropy -40% white haired blue-eyed cats deaf -White cats with one blue eye deaf on that side -gene affects pigmentation and hearing -In mice that lack pigmentation, also lack ear canal fluid and ear canals collapse leading to degeneration of auditory nerves. |
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Three approaches to demonstrate genetic effects on behaviour |
...All involve linking! 1. Using 'natural' behavioural variation 2. Using selective breeding 3. Using strain differences |
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Natural species-species behavioural variation to study genetic effects |
-Interbreed closely related species with different patterns of behaviour to study genetic influences e.g., nest-building behaviour in lovebirds: Species A carries nest material in beak, Species B carries in tail feathers. Hybrid carries material in beak but always looks back and plays with feathers before taking off. |
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Selective breading as a way to study genetic effects on behavioural variation |
-Separate behavioural variants from within a population -select specific individuals to breed and repeat selection process for each generation. -behavioural differences that respond to selective breeding must be due at least in part to genotype. e.g., breed for temperament |
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Domestication*** |
Process by which a population of animals become adapted to man and the captive enviro by genetic changes occurring over generations and environmentally-induced developmental events reoccurring during each generation. |
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Genetic mechanisms influencing domestication |
-Inbreeding -Genetic drift -Selection (artificial, natural, relaxing of natural) |
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Inbreeding is a genetic mechanism that influences |
domestication |
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Genetic drift is a genetic mechanism that infuences |
domestication |
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Selection is a genetic mechanism that influences |
domestication |
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Inbreeding |
-create random changes in gene frequency in small captive populations -decreases genetic variability -"inbreeding depression" -increased risk of genetic disease
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Inbreeding depression |
lowering of fitness or vigor due to inbreeding -egg hatchability -clutch size -milk yield -litter size |
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Genetic drift |
-Certain alleles become randomly fixed or lost -decreased genetic variability -Becomes more severe and more important the smaller the breeding population -"Founder effect"
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Founder effect |
When a population is bred from a few originators, genetic drift can be exceedingly severe, and alleles from one or two founders can dominate the resulting population. -known cause of behaviour problems in show dogs |
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Relaxation of natural selection |
Certain behaviours important for survival in wild lose adaptive significance in captivity. -relaxed selection for food neophobia - domestic mice more accepting of novel food -dogs inferior to wolves in observational learning -maternal protective behaviours |
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Side effects of selection in domestication |
-Behaviour problems -Physiological problems -Immunological problems -Production diseases |
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What are production diseases? |
Diseases caused by management, feeding, and breeding of high producing strains of animals. -e.g., lameness in dairy cattle |
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In dairy cattle, selection for increased milk production has led to... |
-lower energy balance in high producers -higher incidence of metabolic disorders -more days open -longer calving interval -more services per conception -more digestive problems -more leg injuries |
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Problems with pleiotropy |
Over-selection for desired traits can lead to pleiotropic selection for undesired traits. -e.g., broiler chickens selected for breast muscle mass and muscle:carcass weight ratio. Altered weight distribution affects gait, growth of skeleton and internal organs can't keep up. -Turkeys can no longer mate because of traits selected for. Have to use AI. |
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Over selection in broiler chickens |
-Selected for breast muscle mass growth and muscle: carcass weight ratio. -Altered weight distribution affects gait -Skeleton and organs can't keep up. -Reduced cardiopulmonary capacity. -Cannot withstand physical exertion, stress induced mortality with age so breeding birds must be food restricted to survive to sexual maturity.
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Two theories on dog domestication |
1. Humans stole baby wolves and raised them. Only bred tamest ones, others maybe ran away.
2. Wolves "chose" domestication because of easy pickings around where humans lived. Animals that were a little tamer did better because got food waste. Those that didn;t run away got more food and more liekly to reproduce.
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Russian experiment on domestication |
-Dmitry Belyaev -Fox farmers wanted less vicious animals -Began with tamest foxes then for each successive generation only bred tamest. -By 10th generation ears started dropping, tail rising, started to bark, variable coats (all features not in wildtype). -Found that foxes had lower levels of adrenaline (explains tameness) and that adrenaline is on several metabolic pathways |
