Animal - Section A - Chemical Signaling 2 Flashcards
Hormone effects depend on 3 “contexts”
what are they?
- Age
- Sex
- Season (Deer mating season aka roar)
Give an example of secondary sex characteristics in Deer which arise from a the surge in testosterone during ‘roar’
- Antler development
- Changes in behaviour
(Only occurs during that particular season, no other time of the year aka activational affects)
Give an example of an organisational affect?
They are permanent changes which occur early in life
Sex of newborn (left)
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Allowing mouse to develop normally without any intervention it becomes a normal male adult mouse with typical male characteristics (sex/aggression)
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If male mouse in castrated one day postnatally with no further treatment, as an adult it will have female charateristics with male anatomy.
(would try to have sex with males and be less aggressive)
(If castrated and then treated with testosterone externally at 3-5 days it will turn show full male characteristics)
(If a felame mouse if given testostorone at 3-5 days it will show male characteristics as an adult)
Interorganismal chemicals
The below 3 are associated with which type of semiochemical?
-Kairomones
-Allomones
-Synomones
Allelomones (interspecific aka between diff species)
Not Pheromones (intraspecific)
What are semio chemicals?
Chemicals used to convey information between discreet organisms
Explain how a kairomone works and give an example of an animal which reacts to the allelomone.
-Kairomone
Kairomones
‘Only the receiver benefits’
Cladocerans (water fleas) can detect (chemcially) the presence of predatory fish or inverts and these chemicals stimulate the development of protective structures such as helmets and spines.
They also respond behaviourally by changing their patterns of daily activity to avoid predators
Recent research has also shown that algae in turn respond to kairomones released by Daphnia which cause them to aggregate into colonies that are more difficult for Daphnia to eat.
Explain how a kairomone works and give an example of an animal which reacts to the allelomone.
-Allo mones
Releaser has the advantage
Receiver at a disadvantage
Bolas Spider
Synthesize moth sex pheromones to lure moths within range for capture - they then swing their long sticky bolas to catch the moth and other prey - chemical mimicry
Some orchid species produce moth sex pheromones to lure moths to their flowers for the purpose of polination - sexual deception
Explain how a kairomone works and give an example of an animal which reacts to the allelomone.
-Synomones
Benefits both receiver and releaser
clownfish and sea anemones
The territorial fish protects the anemone from anemone-eating fish, and in turn the stinging tentacles of the anemone protect the clownfishfrom its predators.
Lots of introuductions over a few days to build up tolerance to stings, clownfish builds up mucus layer on body to stop stings.
Wasps and plants
In response to attack by aphid herbivores, plants release volatile substances that attract parasitoids such as wasps which injects eggs into aphid, larvae eats aphid from inside out.
special synomone relationship between plant and animal
Interorganismal signalling
Pheromones (same sepcies) can be divided into what 4 functions?
Releaser (RELEASE THE CRACKEN - instantaneous)
The pheromone initiates an immediate behavioural response in the receiver e.g. the standing response of a sow to male sex pheromones in boar saliva
(Male pigs produce androstenal and when the female pigs is in season she immediately adopts a copulatory stance)
Primer (Prolonged physiolgical response by receiver)
Reception of the pheromone by the receiver initiates responses that are more prolonged and may not be immediately obvious, such as stimulating the endocrine systems to increase sex hormone production to increase sperm production in fish.
(Female fish starts secreeting substances substances in water to attract male fish, male fish then start secreting substances which starts the ovulation process in females, this then sends signals which stimulates males to produce sperm - all in the space of 12 hours usually at dawn)
SIgnallers
Indicates to the receiver the ‘condition’ of the releaser
- Female in oestrus releasing a pheromone that signals to the males that she is ready to reproduce potentially (sexual status)
- Males indicating the alpha pressence (social status)
- Indicating territory (scent gland marking and urine indicates indicates terriotry and social standing simultaneously, another male tiger could come along and smell the urine, and it will know from the chemical signiture what the condition of the tiger is and if he can challenge it)
Modulators
The potential response of the receiver is modulated by reception of the pheromone e.g. male human phromones affect mood in women, male salamander courtship pheromones make females more receptive to mating
(psycology experiments, males soing social experiments and women reacting differently to male or female interviewer)
Name the 7 functions of Pheromones?
S.T.T.A.R.C.C
Sexual attraction
Territory marker
Trail markings
Alarms
Recognition
Courtship
Control
What is Mutual naso genital investigation?
Monkeys/Dogs sniffing each other for greetings
Monkeys also produce vaginal copulins which are a mixture of acids with releaser pheromones.
Describe olfactory behaviour in humans
Human males and femals can recognise the scent of their infant offspring. Females can also reliably recognise close family members and children can recognise their siblings by smell alone.
Newborn babies learn their mothers specific scent and by 3 days old can discriminate between the scent of their own mothers breast and that of another lactating female.
The apocrine odour released from sweat glands in the breast and armpit help the baby calm with sleeping difficulties.
Pheromone functions
Sex attraction
-Sex attraction
- Emit sex pheromones to attract males - one of these chemicals is also used by elephants
- Higher molecular weight than alarm pheromones
- Longer lasting
- Male silk moth has 17,000 hairs on each antenna
- Each hair carrys a receptor for the female sex pheromone
- The more hairs you have the more chance you have of intercepting pheromone molecules, but to many hairs would prevent air flowing freely between the hairs and nothing would be picked up.
Humans
Ranking body odour in t-shirts by attractiveness, what you find is people find the t-shirts most attractive are the one most genetically disimmilar to them. If one of the participants in that study (say the t-shirts are all female worn and a male is judging) if one of the participants was the males sister, that person would be ranked least attractive even if it was completely random and the male did not know who it belonged to. This is natures way of reducing inbreeding depression aka incest and bringing couples together with a wide variety of genes.
Pheromone functions
Trail markings
Trail Marking
Ants
Lay pheromonal trails to:
- Find their way back to the nest
- Tell others where food is (better the food the stronger the trail)
Bees
Use Nasanov pheromone to attract bee swarms to new hives
-Used for navigation in cloudy conditions (celestial)
Pheromone functions
Territory marker
Tiger
-Scent marking in territorial mammals
(volatile/short range to determine territory boundary)
-Convey information about the fitness of the territory marker
Fruit fly
- Female fruit fly finds fruit and lays eggs within
- Also deposits Epideictic pheromones
- Pheromones detours other females elsewhere
- No point in laying to clutches as not enough food for all larvae
