Week 3: Development of behavior Flashcards
The nature vs nature controversy
The relative importance of an individual’s innate qualities (“nature”) versus personal experience (“nature”) in determining or causing individual differences in physical and behavioural traits.
Nature
the basic neural circuitry for receiving stimuli in the early stages of development control much of an animal’s behavior
Nurture
contend that environment plays a major role in learning behavior
Other terms used for nature vs nurture
“innate” vs “learned”
“genetically determined” vs “environmentally determined”
“instinct” vs “learning”
Development of worker behavior
Young nurse bee: feeding larvae, feeding nest mates, packing pollen
Old forager: foraging
The tasks adopted by worker bees are linked to their age.
What causes a worker to go through these stages?
Central dogma of molecular biology
DNA <–> RNA –> protein –> behavior
Molecular building blocks —> behavior
Information flow in biological systems
Microarray technology
is used in interpreting the data generated from experiments on DNA, RNA, and protein microarrays.
allows researchers to investigate the expression state of a large number of genes - in many cases, an organism’s entire genome - in a single experiment.
generates very large volumes of data, allowing researchers to assess the overall state of a cell or organism.
Gene activity in the brains of workers
The active components of a worker bee’s genotype change between her nurse phase and her forager phase
Juvenile hormones (JHs)
JHs regulate development, reproduction, diapause, and polyphenisms
JHs are secreted by a pair of endocrine glands behind the brain called the corpora allata
Young nurse bee: low JH concentration
Old forager: high JH concentration
Young bees — (+) JH —> precocious foragers
Young bees – (-) corpora allata–> the bees delays its transition to foraging
Bees without corpora allata – (+) JH –> bees switch to foraging
Social environment and task specialisation
In experimental colonies composed exclusively of young workers, the young bees do not forage if older forager bees are added to their hive.
If young bees are added instead, the young residents develop into foragers very rapidly.
In honey bees, hormone production responds to the social environmental of individuals
Honey production
Foragers collect nectar from flowers
Foragers regurgitate nectar and transfer it to nurse bees
Nurse bees deposit nectar in cells
A deficit in social encounters with older foragers may have stimulated an early developmental transition from nurse to forager behavior
Ethyl Oleate
Is a primer pheromone composed of a fat acid compound.
Is released by foragers to slow maturing of nurse bees
Is transferred from foragers to nurses with nectar
Acts as a distributed regulator to keep the ratio of nurse bees to forager bees in the balance that is most beneficial to the hive
Ethyl oleate works as a negative feedback. When there’s ethyl oleate, then JH won’t be produced.
Ethyl oleate is an environmental signal
DNA is both inherited and environmentally responsive
Worker foraging behavior cannot be purely “genetically determined” because the behavior is the product of literally thousands of chemical interactions between the bee’s genes and its environment.
The information in a gene is expressed only when the gene is in the appropriate environment.
Environmental signals influence gene activity.
When a gene is turned on or off by changes in the environment, the resulting changes in protein production can alter the activity of other genes.
Therefore, no trait can be purely “genetic.”
Problems of the traditional view off behavioural development
It’s impossible to rear an individual in complete isolation from the environment
Interaction between the internal and external environment of the organism during key stages of the development may have effects on behavior
Interactive view of behavioural development
The individual organism continually interacts with its internal and external environment
The individual and its environment are different at different times during development
Development is an interactive process
- Some of the genes can be turned on and off by the appropriate signals, which are ultimately derived from the environment
- The development of any trait is the result of an interaction between the genotype of a developing organism and its environment
Differences between individuals
Although no behavior is either purely genetic or purely environmental, differences between individuals can arise as a result of developmental differences stemming from differences in either their genes or their environments.
Environmental differences cause behavioral differences
Kin recognition in Belding’s ground squirrels
Genetic differences cause behavioral differences
Overwintering sites in blackcap warblers
Belding’s ground squirrel
group-living, burrowing rodents found alpine and subalpine regions of the western USA
socially active above ground
Each mother produces one litter annually of 5-8 pups.
The squirrels possess scent-producing glands, including one around the mouth and another on the animal’s back.
These squirrels regularly sniff the oral glands of other individuals, as if they were acquiring odor information.
Kin discrimination in Belding’s ground squirrels
The newborn offspring of captive females were switched around at birth, creating four classes of individuals
(1) siblings reared apart
(2) siblings reared together
(3) nonsiblings reared apart
(4) nonsiblings reared together
After having been reared and weaned, the juvenile ground squirrels were placed in an arena in pairs and given a change to interact.
Animals that were reared together, whether actual siblings or not, tolerated each other.
Armpit effect
Biological sisters reared apart displays less agression towards each other than other combinations of siblings reared apart
The squirrels had some way of recognising their siblings that was not dependent on living with them as youngsters
Armpit effect:an individual learns to identify closely related individuals by their door, comparing it to its own smell for phenotype matching
Odor-testing methods
Pregnant squirrels were captured and were moved to laboratory enclosures.
Juvenile squirrels had no prior experience with the odors of relatives.
Plastic cubes were rubbed on the dorsal glands of squirrels.
Odor donors: self, varying degrees of relatives, nonkin
Can inexperienced young squirrels discriminate between unfamiliar relatives and nonrelatives on the basis of odor cues alone?
Belding’s ground squirrels learn their own odor
Juvenile squirrels were first given 3 trials during which they could investigate their own odors applied to plastic cubes.
The squirrels’ decline in responsiveness to their own dorsal gland scents over these initial trials → learning
Cubes with scent from close relatives received less attention than those with scents from distant relatives or nonkin.
They have the capacity to treat individuals differently on the basis of this highly specific learned label of relatedness.
Different wintering sites of blackcap warblers
Blackcaps living in southern Germany and Scandinavia first go southwest to Spain before turning south to Western Africa
Blackcaps living in Eastern Europe migrate southeast before turning south to fly to Eastern Africa
Where do the birds that winter in Great Britain come from?
It turns out they do not come from Scandinavia
Migration experiments
Wild blackcaps were captured in Britain during the winter and were taken to a laboratory in Germany.
The birds were kept indoors. Pairs of warblers were released into outdoor aviaries, where they bred.
Once the young birds were several months old, the young warblers and parents were placed in a funnel cage to determine the direction in which the birds intended to travel.
Genetic differences can cause behavioural differences
Experienced adults and young novices alike, oriented due west.
These data showed that the adults, which had been captured in wintery Britain, must have traveled there by flying west from Belgium or from central Germany.
This point is confirmed by the discovery of some blackcaps in Britain that had been banded earlier in Germany.
Furthermore, young birds whose parents oriented in a southerly direction did the same in fall.
Behavioral differences in migratory orientation were caused by genetic differences between the two populations of individuals.
