L4 Hormones, clocks and behaviour Flashcards
What type of factor influencing behaviour are hormones?
Proximate
What causes eating behaviour?
Hunger
What hormones control hunger?
leptin and Ghrelin
What does Leptin do and where is it released?
Released form specialised from fat storage cells, it is a hunger inhibitor. The more fat cells, the more leptin released
What does Ghrelin do and where is it released?
Released from stomach in response to low leptin levels, causes hunger
What causes motivation to mate?
Hormones, a balance between testosterone, estrogen and progesterone
What is testosterone?
Primarily male sex hormone and anabolic steroid
What is estrogen?
Primarily female sex hormone
What is progesterone?
sex hormone involved in menstrual cycle, pregnancy and embryogenesis
What is the difference between hunger and sexual motivation?
Hunger restores physiological balance, mating doesn’t
What did Juergen Aschoff do?
Pioneer in biological rhythms, research in chronobiology,
What is the concept of a zietgeber?
A time keeper, or internal clock that drives biological rhythms
What may be the adaptive significance of a biological rhythm?
Synchronisation with the changing environment, whether daily, monthly or yearly, for coordination of metabolic process etc.
What is a circadian rhythm?
24 hour rhythm, e.g. resting, sleeping, eating, temperature etc
What is a circanular rhythm?
Monthly cycle e.g. menstruation
What is a circannual rhythm?
Yearly cycle e.g. migration and reproduction, hibernation
Regarding biological rhythms, what was the test on bending ground squirrels and what did it show?
Were held at constant light levels/temp to determine if hibernation timing and length stayed constant - it didn’t
How did they test environment dependent control on circadian rhythms?
Shany fish normally live in tidal rock pools, removed the tidal element and investigated how long fish kept up normal cycle, which depends on the tides, lasted for about 4 or 5 cycles then stopped.
What would you expect from an animal that lives under constant conditions and why is it significant?
exhibit no circadian rhythms, acts as a test for the adaptive significance of biological rhythms, shows they have a purpose
What controls the onset pf reproduction in birds?
pituitary hormones
Why is it difficult to measure hormone control and how do they do it?
Difficult to measure as such small measures, however radio-immunoassay can be used
What are the benefits of testosterone?
Promotes sperm production and activates sexual behaviour
What are the costs of testosterone
Suppresses immune system and stimulates aggressive behaviour
How did they test sex drive in guinea pigs?
testes removed and sex drive recorded, levels went down until testosterone was injected, showed how testosterone affects sex drive
What experiment was used to show how testosterone affects aggression and sexual competition?
showed by varying levels of testosterone in female dunnocks, the levels were higher in females competing for males in a polygynous population than females I na monogamous population
What affect does testosterone have in egg yolk in canaries?
testosterone content increases with each egg laid and social rank is positively correlated with testosterone levels
How does testosterone influence paternal care?
morning testosterone levels are higher in low investing men, in both monogamous and polygamous situation
What example illustrates the costs of testosterone?
Side blotched lizard Uta stansburiana, throat colour depends on testosterone levels, however correlate with survival rate - lower with high testosterone levels
Why do elevated testosterone levels correlate with reduced survival?
Because testosterone is an immunosuppressant
