Social Behaviours

Question 1

What are social behaviours?

Answer 1

Social behaviours encompass interactions between individuals that benefit one or more of the individuals

Question 2

Two types of social behaviours

Answer 2

1. Affiliate
2. Aggressive

Question 3

What are affiliate behaviours?

Answer 3

Behaviours that bring animals together

Question 4

What are aggressive behaviours?

Answer 4

Behaviours that keep animals apart

Question 5

Costs of sociality?

Answer 5

1. Disease transmission
2. Competition for resources
3. Increased conspicuousness to predators

Question 6

Benefits of sociality

Answer 6

1. Antipredator detection, defence and dilution
2. Foraging/hunting efficiency
3. Group defence of resources
4. Increased mating opportunities

Question 7

Adaptive function of affiliation- monogamous species

Answer 7

The formation of long-term pair bonds is critical for their reproductive success- both parents have a ”50% stake” in the offspring and it’s likely the offspring would die if either parent abandoned them

Question 8

Adaptive function of affiliation- other mating systems

Answer 8

The requirement for increased proximity during mating is potentially dangerous

Question 9

Adaptive function of affiliation-hormones

Answer 9

Hormones that evoke affiliation serve as a proximate means of inciting cooperation, as well as suppressing avoidance behaviours from frightening or aversive stimuli

Question 10

Study of affiliation- voles

Answer 10

Male & female prairie voles form long-term pair bonds characterised by a preference for a familiar partner and selective aggression towards unfamiliar conspecifics

When socially naïve individuals meet, they engage in a brief session of olfactory investigation followed by prolonged periods of sitting in close proximity

Question 11

Adult affiliate behaviours in response of young to separation

Answer 11

When prairie vole pups are isolated from their families for 5 minutes, they emit distress vocalisations and plasma corticosterone concentrations elevate four-to-six folds

When montane vole pups are socially isolated, they do not emit any distress vocalisations and there are no changes in blood corticosterone concentrations

However, they do not respond to other stressors - which suggests that they just don’t find social isolation stressful

Question 12

Endocrine bases in vole social organisation- testosterone

Answer 12

Male meadow and montane voles generally have higher blood testosterone concentrations than male prairie voles

Question 13

Endocrine bases in vole social organisation- oxytocin

Answer 13

In prairie voles, oxytocin receptors were highest in the prelimbic cortex, nucleus accumbens, and lateral amygdala, whereas receptors were not evident in these brain regions in montane voles

Question 14

Endocrine bases in vole social organisation- vasopressin

Answer 14

Prairie roles have higher numbers of V1aR in the ventral palladium, medial amygdala, and mediodorsal thalamus compared to montane voles

Question 15

Endocrine bases in vole social organisation- corticosterone

Answer 15

Prairie voles display very high basal corticosterone concentrations, and have higher numbers of CRF2 in the nucleus accumbens compared to meadow and montane voles

Question 16

Endocrine bases in vole social organisation- corticotropin releasing factor type 2 receptors (CRF2)

Answer 16

CRF is released from the paraventricular nucleus of the hypothalamus, which subsequently caused the release of adrenocorticotrophic hormones from the anterior pituitary into the bloodstream

ACTH induces the synthesis and release of glucocorticoids from the adrenal cortex

Question 17

Endocrine bases in vole social organisation- corticosterone injections

Answer 17

In socially naive males, corticosterone injections facilitated the development of partners preference, whilst adrenalectomized males did not form partner preference

In socially naive females, corticosterone injections inhibited pair bond formation,whereas partner preferences were formed within 1hr in adrenalectomized females I

Question 18

Evolution of affiliation

Answer 18

Affiliation is thought to have evolved from reproductive and parental behaviour for example attachment, whereby short-term associations nave evolved into long-term social bands

Question 19

Affiliate behaviours and hormones

Answer 19

Affected by peptide hormones and glucocorticoids- these appear to function in affiliation by affecting the neurotransmitters dopamine and serotonin

Many of these hormones appear to suppress the “fear” or “stress” of social contact, to allow individuals to come together and engage in social or mating behaviours

Question 20

When do aggressive behaviours occur?

Answer 20

Exists whenever the interests of or more individuals are in conflict, usually over limitedresources

Question 21

Four reasons androgen steroid hormones mediate aggressive behaviours

Answer 21

1. Seasonal variation
2. Puberty
3. Sex differences
4. Individual differences

Question 22

Seasonal changes in social behaviour- stags

Answer 22

Castration or stags during the winter mimics the normal process and causes them to shed their antlers prematurely- this causes them to plummet in social rank

Question 23

Winter changes in stags

Answer 23

Miles retain their antlers, were more aggressive and climbed in social rank during spring and summer

They only showed meeting behaviours during the appropriate autumnal breeding season

Question 24

Summer changes in stags

Answer 24

Males were more aggressive and climbs in social rank, even before the androgen could stimulate antler development

Question 25

Seasonal changes in social behaviour- rodents

Answer 25

Mini rodent species shift from highly territorial social strategy during the breeding season to a social and highly interactive strategy in the winter In addition to the change in blood plasma antigen concentration, rodents also have seasonal changes in the androgen receptor sensitivity

Question 26

What is the adaptive function of this shift?

Answer 26

During the breeding season, animals benefit from controlling resources to promote their survival and that of their offspring, whereas they benefit from group living over the winter to conserve energy and enhance survival

Question 27

Puberty and aggression

Answer 27

The testes grow larger and under the influence of LH from the anterior pituitary the leydig cells secrete, increasing amounts of androgens into the circulatory system. This increases aggression.

Question 28

Puberty and Syrian hamsters

Answer 28

Prior to puberty male, Syrian hamsters, engage in play fighting. During puberty, this moves into the adult version of aggression From mid puberty attacks aimed at the flanks, then become adult like to attack the underbelly and the rear

Question 29

Puberty and social stress

Answer 29

Repeated exposure to social stress early in puberty accelerates, transition from play fighting to adult aggression Essentially puberty can be described as a period of increasing HPA activity

Question 30

Puberty, dispersal strategies and avian and mammalian species

Answer 30

There are two strategies for attempting to join a new trip, which appears to be influenced by hormonal factors Sons of high-ranking females often have more outgoing personalities, explore further from their mothers and engage in more rough and tumble play Sons of Noah ranking females have high plasma cortisol concentrations, and tend to employ the strategy of sneaking into a new troop after establishing familiarity from the periphery

Question 31

Sex differences, male and female mice

Answer 31

If male mice are castrated before six days old, and then receive testosterone treatment in adulthood the exhibit low levels of aggression Females ovariectomised before six days old, but given androgens in adulthood, do not express male like levels of aggression If these males or females receive testosterone treatment before six days old and into adulthood, they exhibit levels of aggression, similar to typical male, mice

Question 32

Sex differences in dispersal in squirrels

Answer 32

Female offspring were injected with testosterone. Proportionate dissolved in sesame oil several days after birth. By day 60, 75% had dispersed to new sites following dispersal routes and travel distance is comparable to males 70% of the male siblings had also dispersed 8% control female had dispersed

Question 33

Sex differences in play behaviour

Answer 33

Males tend to be more aggressive than females, this sex difference in behaviour manifest itself early in development during the expression of play behaviour

Question 34

Sex differences in play behaviour- males

Answer 34

Males engage in more rough and tumble play, more chasing, more threatening behaviour, and initiate play more than females- this increased aggression appears to only require prenatal androgen exposure

Question 35

Sex role reversal- female sandpipers

Answer 35

Some female sandpipers exhibit brightly coloured plumage, will compete amongst themselves for access to emails and a very aggressive towards other females However, this six role reversal is not accompanied by a reversal in typical male: female, blood androgen concentrations

Question 36

Female sandpipers testosterone levels

Answer 36

Before per formation, female testosterone concentrations are quite low, but after pairing shows a temporary 7x increase- so female aggression reflects increase sensitivity of brain structures to steroid hormones

Question 37

Individual differences and blood testosterone concentration in mice

Answer 37

Mice were either rated as aggressive or non-aggressive All individuals were than castrated and became equally passive They were all provided with equal doses of this just arrived, and then tested again Males that were previously aggressive became so again whilst previously non-aggressive males remained docile

Question 38

Individual differences- experience in rodents

Answer 38

Experience also seems to be important in the relationship between hormones and aggressive behaviour Castrated, mice and rats without prior aggressive experiences, rarely fight when tested with another male If they were castrated after aggressive, encounters have been experienced, aggressive behaviour, slowly, decline over a long period of time, post surgery

Question 39

Physiological mechanisms

Answer 39

Function or structural abnormalities in one or more of the prefrontal cortex, amygdala, hippocampus, medial preoptic area, hypothalamus, anterior cingulate cortex, insular cortex, and ventral strontium, can increase susceptibility for impulse, aggression and violence

Question 40

What are the four distinct regulatory pathways of physiological mechanisms?

Answer 40

1. Androgen responsive pathway 2. Oestrogen responsive pathway 3. Synergistic Pathways 4. Direct testosterone mediated pathway

Question 41

What is the androgen responsive pathway?

Answer 41

Responds to testosterone itself or DHT Androgen receptors have been found in several brain regions in rodents: bed, nucleus of the stria terminalis, medial preoptic area, lateral septum and medial amygdala

Question 42

What is the oestrogen responsive pathway?

Answer 42

Response to a estradiol derived from testosterone Gonadally intact mice like in the gene for a oestrogen, receptor subtype displayed, virtually no aggression, even when castrated and given testosterone implants Gonadally Intact mice lack in the gene for B oestrogen receptor subtype, just displayed normal, aggressive behaviour

Question 43

What is a synergistic pathway?

Answer 43

Responds to both androgenic and oestrogenic metabolite of testosterone

Question 44

Direct testosterone, mediated pathway

Answer 44

Only response to testosterone

Question 45

Physiological, mechanisms and serotonin

Answer 45

Serotonin appears to be the major regulator of aggressive behaviours, particularly the 5-HT1A and 5-HT18 Receptor subtypes In mammals, generally low 5HT function/receptor activation or associated with high aggression, while high five HT function/receptor activation or associated with low aggression

Question 46

Serotonin levels in fish (phases)

Answer 46

High 5HT function leads to reduced aggression and so is often seen in more subordinate individuals Phase 1-4 groups of four fish and determine the dominance hierarchy Phase 2 - all number one fish in group one and all number to fish in another et cetera Fish that were subordinates in phase 2, showed higher 5 HT activity which curtail their aggression behaviour, presumably to avoid fighting with a dominant fish

Question 47

Serotonin levels, depending on social or solitary environments, aggressive behaviour, and vervet monkeys

Answer 47

The effects of 5HT may depend on whether the animal was raised in social or sonic, three environment Subordinate male version of a monkeys were selected to receive either drugs, that enhance serotonin activity or a drug that reduced it When they received the former, they came dominant but when they receive the latter they treated conspecifics became dominant