Lecture 5 Flashcards
Organisation of behaviour
Army ants
=colony behaves like 1 organism
- around 18
- aggressive nomadic behaviours
- kill by overwhelming prey with large numbers
- alternate between stationary stage where queen enlarged laying eggs
- normadic where colony moves for food
Hunting snakes
Mojave one of worlds most venomous snakes
- Heat sensing
- Taste: picks up odours
- Touch
- Animal they hunt leave a trail of heat and smell for them to follow
- All contained within same skull
- No reason to suppose that these are interconnected
Praying mantis
- when inhibitory connections cut
- subesophageal ganglion sends stream of excitatory messages to downstream ganglia
- with the result that the animal attempts to do several competing activities at the same time
Sexual cannibalism
Male attracted to larger female, she’ll bite his head off when in range, male will start to engage in activities as inhibitory connections cut
Blowfly
- ingestion initiated by simulation of oral taste receptors
- terminated by signals from foregut (originate stretch receptors)
- recurrent nerve coveys signals to the brain where they counteract input from peripheral taste receptors
-Transection of the recurrent nerve interferes with this inhibitory feed-back system and causes a fly to become hyperphagic (will explode)
The cricket
-chirping behaviour connected to light and dark cycles
When put under 24hr of light, no longer tied to when dusk would have been, chirping later and later and later, end with no specific pattern
Clear indication internal regulation for chipping behaviour, but clock is imposing being regulated by change from light and dark, and without that it just goes off whenever
*but shifts when there are no light cues, showing that there is internal and external entrainment of this response
The cricket: eyes
- Severing retinal connections (so they can’t see) produces slow drift in circadian rhythm
- indicating that is where the master clock or pacemaker mechanism is located
- severe optic lobes: behaviour becomes random, means there is an internal clock in the lobe
- needs daylight to keep pace, somewhere in the optic lobe
Control of circadian rhythms
- lesion and transplant studies show that in mammals the clock is located in the suprachiasmatic nucleus (SCN) of the hypothalamus
- all animals seems to have pace maker of circadian rhythms
- melatonin can shift your clock
Prokineticin 2
-P2 high day time, low night time, very clear circadian rhythm to do with pk2
Lunar cycles
- when food is plentiful animals avoid feeding during moonlight
- when food is in short supply animals feed during moonlight and eventually even daylight
Yearly cycles: squirrel
Animals held in constant darkness and at a constant temperature nevertheless entered hibernation (green bars) at certain times year after year
Circannual rhythm stonechat
- male stonechat still underwent a regular long-term cycle of testicular growth and decline
- as well as regular feather
- cycle was not exactly 12 months long however, so the timing of molting and testicular growth gradually shifted over the years
- Move animal to different part of the world, cycles start not to be entrained therefore cues are to do with the environment
Regulation of infanticide in male house mice
(A) Male mice were held under artificial ‘slow-day’ and ‘fast-day’ experimental conditions. (B) Most of the males under fast-day conditions had stopped being infanticidal by 20 real days (22 fast days) after mating; males experiencing slow-days did not show the same decline in infanticidal behaviour until nearly 25 real days had passed
-number of times it goes from light to dark is important regulated behaviour
Rufous sparrow
-seasonal changes in the song control regions of brain
- summer rainfall triggers changes
- size of HVC and RA increase following monsoon thunderstorms
-changes linked to an increase in singing after monsoon has begun
Naked mole rat
lack of circadian rhythm
-because they live underground so its always dark
