Chapter 3: the developmental and genetic basis of behavior Flashcards
The development of behaviour is an ____ ______in which ____ information interacts with changing ____ and ____ environments in ways that assemble an organism with special properties and abilities
The development of behaviour is an interactive process in which genetic information interacts with changing internal and external environments in ways that assemble an organism with special properties and abilities
example: language acquisition occurs as a gene-environment interaction
_____ ____ __ is an enzyme that breaks down neurotransmitters and is associated with the ____ gene.
MONOAMINE OXIDASE A is an enzyme that breaks down neurotransmitters and is associated with the WARRIOR Gene.
explain the warrior gene and aggressiveness in children
Monoamine oxidase A is an enzyme that breaks down neurotransmitters – e.g., dopamine, seratonin, norepinephrine
There are several alleles for the gene – one is associated with a predilection toward violent behaviour
There is strong evidence for a gene-environment interaction –with the aggressive variant, children subject to violence and abuse are more likely to become violent and abusive later in life than individuals with other alleles of the gene
Explain how both genes and the environment contriute to the development of forgaing behavior in the honey bee
Tasks, such as foraging for pollen (seen here), adopted by worker bees are linked to their age. When they are young, they clean and take care of larvae. when they are older, the pack pollen and forage.The genotype must respond to the environment in a way that influences development.
what chemical is transferred to younger bees by older bees? how does this effect their development?
The key is ethyl oleate: it is transferred by foragers in nectar and inhibits the development of foraging behaviour (by inhibiting juvenile hormone) in nurse bees
– juvenile hormone is low in nurse bees and high in foragers. The hormone is responsive to the social environment.
How do genes and environment interact to make bee queens?
To make a queen, workers feed larvae royal jelly –a protein, ROYALACTIN, that triggers gene development
A gene – environment interaction
But how does a simple protein influence morphological and behavioural development?
Epigenetic modifications - alterations of the genome that do not change DNA sequence - are thought to play a role.
how does royalactin protein help form a bee queen
epigenetic modifications of larvae
the central dogma of molecular biology:
DNA is transcribed into mRNA, which is then translated at a ribosome into a protein. The protein is made of multiple other polypeptide chains.
Epigenetic modifications
DNA is coiled tightly around histone proteins. Chemicals or other changes to these proteins (histone modifications) or to the DNA itself (DNA methylation) can influence the expression of DNA.
For example, methylating a gene can serve as an ‘off switch’ for a gene.
Experimental manipulation of the enzyme controlling DNA methylation suggests that this epigenetic process is related to the production of queens vs. workers in honey bees.
In addition to epigenetic modifications, how else can a gene be effectively silenced in honeybees to affect queen vs worker development?
Using RNA-interference (RNAi) to control gene expression in honeybees had similar effects to ROYAL JELLY – silencing a gene for an enzyme that controls DNA methylation resulted in the production of queens.
therefore, to produce workers, you must de-methylate the gene (turn the worker gene on). if the worker gene is methylated, or if royal jelly is fed, it will result in more queens.
Discuss the social environment and task specialization by worker bees when you add older or younger bees to the colony
When older bees are added to a colony, young bees do not forage – when young bees are added, a high proportion of young bees forage.
therefor, it can be suggested that older bees prefer to forage, and will inhibit younger ones from foraging by giving them ethyl oleate, forcing them to care for young larvae instead.
NOTE: Although no behaviour is purely genetic or purely environmental, variation among individuals can arise as a result of development differences stemming from differences in either their genes OR their environments.
explain the genetic and environmental influences of interactions between beldings ground squirrels
The newborn offspring of captive females were switched around to create four classes of individuals:
- Siblings reared apart
- Siblings reared together
- Nonsiblings reared apart
- Nonsiblings reared together
After weaning, pairs of individuals were placed together in an arena and allowed to interact:
SISTERS reared apart displayed significantly less aggression toward each other than other combinations of siblings reared apart (ex/ m-m, f-m), which were as aggressive to each other when they met in an experimental arena as nonsiblings reared apart.
Explain how odor affects interactions between different belding ground squirrels
Belding’s ground squirrels learn their own odor
Juvenile squirrels were first given three trials during which they could investigate their own odors applied to plastic cubes. Note the squirrel’s decline in responsiveness to their own dorsal gland scents over these initial trials. Then the squirrels were provided with plastic cubes daubed with dorsal gland odors from four categories of individuals. Cubes with scents from close relatives received less attention than those with scents from distant relatives or nonkin.
Although many differences in behavioural phenotypes have been linked to differences in environment, many others have been linked to ____ differences among individuals
Although many differences in behavioural phenotypes have been linked to differences in environment, many others have been linked to genetic differences among individuals— it’s not just the environment that induces behavioral change
Explain the difference in feeding in coastal and inland garter snakes. how is feeding genetically influenced?
Young snakes from coastal populations tended to have high slug feeding scores: inland garter snakes were unlikely to eat even one slug cube.
Coastal snakes like to eat slugs more.
F1 generation of both snakes raised in the SAME condition resulted in snakes from coastal parents liking slugs more, despite being raised in the same condition as inland young. therefore, slug preference is not environmentally influenced– coastal snakes are genetically different than their inland counterparts for food preferences.
What is imprinting
IMPRINTING: a young animal’s early social interactions, usually with its parents, lead to learning such things as what constitutes an appropriate sexual partner
Explain the cross fostering experiment that point to the fact that imprinting is both environmentally and genetically influenced.
Tore Slagsvold cross-fostered blue and great tits in nests
As adults this disrupted normal pair formation within own species: great tits fostered by blue tits chose blue tits as mates; some blue tits fostered by great tits chose great tits as mates (environmental influence on mate choice)
BUT:
Female blue tits who “chose” great tits as social mates only produced blue tit nestlings: indicates that there was a genetic drive to mate with a member of their own species and then go back to their social mate.
Clark’s nutcrackers may scatter as many as 33,000 seeds in up to 5,000 caches that may be as far as 25 km from the harvest site. The fact they can remember the location of seeds for six to nine months indicate that they have good ___- memory
SPATIAL
When does selection favor learning?
Selection favours investment in the mechanisms underlying learning only when there is environmental UNPREDICTABILITY that has reproductive relevance for individuals. The ability to learn comes with a price tag.
Learning abilities reflect the different ecological ______
Learning abilities reflect the different ecological circumstances.
Why are cannibal morphs more likely to develop when there are more unrelated individuals in the population OF TIGER SALAMANDERS?
DUE TO KIN SELECTION- YOU DON’T WANT TO EAT SOMEONE WHO SHARES YOUR GENES AND HAS THE ABILITY TO PROPAGATE YOUR GENES FURTHER.
what is the biochemical process that allows non-territorial males to convert to territorial males in the cichlid species (developmental plasticity polyphenism)
When a territorial male is removed, a nonterritorial subordinate may replace it. Within minutes of the removal of the dominant male, a subordinate male may begin to behave more aggressively than before. This change in behaviour is correlated with a surge in the activity of a specific gene in the preoptic region of the fish’s brain. This gene may initiate a sequence of other genetic changes that provide the physiological foundation for dominance behaviours. Note that the activity of the egr-1 gene ramps up its activity during the transition from subordinate to dominant status but then falls back once the male has become dominant
The switch is triggered by upregulation for GnRH PROTEIN which is triggered by upregulation of the egr-1 gene;
1) sensory input “i am gonna be more dominant” activates the egr-1 gene in the hypothalamus
2) more egr1 gene
3) more GnRH1 neurons
4) more GnRH1 neurons project to the pituitary for the relase of LH and FSH
5) LH and FSH cause the GnRH1 neurons to increase in size
6) non-territorial males produce more sperm. after transition to dominant male, the egr1 gene activity falls
