Lecture 4: Hormoes, Clocks & Behaviour

Question 1

Behaviour can be caused by

Answer 1

external and internal stimuli & by an interaction between those two (e.g. bird song)

Question 2

behaviour caused by internal stimuli caused by

Answer 2

hormones & clocks

Question 3

eating is a type of behaviour, what causes eating? Hunger. what causes hunger?

Answer 3

hormones: Leptin & Gherlin

Question 4

Leptin is released from where?

Answer 4

specialised fat-storage cells

More fat storage cells, more Leptin released into blood and via hypothalamus = LESS hunger

Question 5

if Leptin levels are low…

Answer 5

checked by hypothalamus, causes a release of Gherlin form stomach = HUNGER

Question 6

motivation to mate is controlled by

Answer 6

hormones

Question 7

hunger & reproduction are examples of..

Answer 7

Drives

Question 8

Gammarus pulex - freshwater amphipod and reproduction strategy

Answer 8

-males mate guard as females cant reproduce till shed outer skin. Males are able to distinguish between females form the malting hormones they release to identify which will malt first

Question 9

motivation to mate in mammals and birds controlled by

Answer 9

balance between testosterone, estrogen and progesterone

Question 10

in Females Rhesus monkeys motivation to mate is greatest: at the point in her estrus cycle

Answer 10

when the hormone oestrogesn peak and likelihood of fertilisation is high

Question 11

difference between hunger and sexual motivation

Answer 11

• hunger restores a physiological balance

- mating does not

Question 12

Biological rhythms experiment:

Answer 12

Pioneer is Juergen Aschoff
-people in concrete bunker underground to remove outside cues, still had 24hr pattern. Deteriated the longer they were in there.
discovery of: a zeitgeber

Question 13

How do we/animals maintain regular behaviours:

Answer 13

internal clock and Aschoff’s concept of A ZEITGEBER - time-keeper

Question 14

all animals and plants are full of clocks that drive rhythms: Very short:

Answer 14

locomotion and heart beat

Question 15

all animals and plants are full of clocks that drive rhythms: Circadian

Answer 15

24 hours rhythms

-resting/sleeping, eating, temperature

Question 16

all animals and plants are full of clocks that drive rhythms: Circalunar

Answer 16

monthly

-menstrual cycle

Question 17

all animals and plants are full of clocks that drive rhythms: Circannual

Answer 17

yearly

migration, reproduction

Question 18

example of circannual: squirrels

Answer 18

hibernating/active squirrel under ground

- 4 years, slowly fell out of pattern

Question 19

example of environment-dependent control. Shanny:

Answer 19

Shanny (fish) kept in constant (non-tidal) conditions maintain their cycle for about 4/5 tidal cycles.
-quickly restored if exposed to tidal cycle again

Question 20

sophisticated clock: migrating birds

Answer 20

• little birds migrate at night
• birds of prey - bigger birds migrate in the day
• • day = sun
• • night = stars

-ruthless natural selection - if they don’t make it they simply die

Question 21

test circadian rhythm: if there’s an animal that lives under constant conditions (e.g. where the difference between day and night) is irrelevant, predict that they should exhibit no circadian rhythm

Answer 21

naked mole rat live underground, rarely coming up to surface - no external cues. lack circadian rhythm

Question 22

how do internal clocks work - this discovery?

Answer 22

-timing of breeding - controlled by circannual rhythm.
-pituitary hormones controlling onset of reproduction in birds
-difficult: such tiny amount of hormone
(( new tech in late 1960’s: radio-immunoassay = massive increase in precision))
-Brian Follett, Philip Mattocks and Don Farner in 1974 showed that only when day-length and internal rhythm coincided were pituitary hormones secreted.
-Mechanism: using tiny spots of luminescent paint on needles; they could see which part of the brain responded to light

Question 23

insects (drosophila) male ‘mate guarding’ ?

Answer 23

-male which had sex last (last male sperm precedence) is which will fertilise eggs.
SO: copulates, sperm & anti-aphrodisiac & hormone which speeds up egg laying

Question 24

Testosterone benefits and costs

Answer 24

• promotes sperm production
• activates sexual behaviour
• suppresses immune system
• stimulates aggressive behaviour

Question 25

sex drive in male guinea pigs

Answer 25

before castration: high sex drive

• after castration: SD drops (not instantly)
• T therapy, SD increases

Question 26

aggression and T in female dunnocks Prunella modularis

Answer 26

-T concentrations were higher in females competing for male sin polygynous groups than in gfemales in monogamous relationship.

Question 27

T in birds’ eggs - canaries

Answer 27

more testosterone –> beg more.

Extra T in later layed eggs

Question 28

in humans T levels: monogamous and polygynousl

Answer 28

higher in poly, lower in mono

-castrated males liver 15-20 years longer

Question 29

cost of testosterone:

Answer 29

reduces immue function - reduces survival.

-Uta lizard e.g. higher T less likely to survive to next spring