Social Behaviours Flashcards
What are social behaviours?
Social behaviours encompass interactions between individuals that benefit one or more of the individuals
Two types of social behaviours
- Affiliate
- Aggressive
What are affiliate behaviours?
Behaviours that bring animals together
What are aggressive behaviours?
Behaviours that keep animals apart
Costs of sociality?
- Disease transmission
- Competition for resources
- Increased conspicuousness to predators
Benefits of sociality
- Antipredator detection, defence and dilution
- Foraging/hunting efficiency
- Group defence of resources
- Increased mating opportunities
Adaptive function of affiliation- monogamous species
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
Adaptive function of affiliation- other mating systems
The requirement for increased proximity during mating is potentially dangerous
Adaptive function of affiliation-hormones
Hormones that evoke affiliation serve as a proximate means of inciting cooperation, as well as suppressing avoidance behaviours from frightening or aversive stimuli
Study of affiliation- voles
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
Adult affiliate behaviours in response of young to separation
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
Endocrine bases in vole social organisation- testosterone
Male meadow and montane voles generally have higher blood testosterone concentrations than male prairie voles
Endocrine bases in vole social organisation- oxytocin
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
Endocrine bases in vole social organisation- vasopressin
Prairie roles have higher numbers of V1aR in the ventral palladium, medial amygdala, and mediodorsal thalamus compared to montane voles
Endocrine bases in vole social organisation- corticosterone
Prairie voles display very high basal corticosterone concentrations, and have higher numbers of CRF2 in the nucleus accumbens compared to meadow and montane voles
Endocrine bases in vole social organisation- corticotropin releasing factor type 2 receptors (CRF2)
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
Endocrine bases in vole social organisation- corticosterone injections
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
Evolution of affiliation
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
Affiliate behaviours and hormones
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
When do aggressive behaviours occur?
Exists whenever the interests of or more individuals are in conflict, usually over limitedresources
Four reasons androgen steroid hormones mediate aggressive behaviours
- Seasonal variation
- Puberty
- Sex differences
- Individual differences
Seasonal changes in social behaviour- stags
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
Winter changes in stags
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
Summer changes in stags
Males were more aggressive and climbs in social rank, even before the androgen could stimulate antler development
Seasonal changes in social behaviour- rodents
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
What is the adaptive function of this shift?
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
Puberty and aggression
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.
Puberty and Syrian hamsters
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
Puberty and social stress
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
Puberty, dispersal strategies and avian and mammalian species
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
Sex differences, male and female mice
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
Sex differences in dispersal in squirrels
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
Sex differences in play behaviour
Males tend to be more aggressive than females, this sex difference in behaviour manifest itself early in development during the expression of play behaviour
Sex differences in play behaviour- males
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
Sex role reversal- female sandpipers
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
Female sandpipers testosterone levels
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
Individual differences and blood testosterone concentration in mice
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
Individual differences- experience in rodents
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
Physiological mechanisms
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
What are the four distinct regulatory pathways of physiological mechanisms?
- Androgen responsive pathway
- Oestrogen responsive pathway
- Synergistic Pathways
- Direct testosterone mediated pathway
What is the androgen responsive pathway?
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
What is the oestrogen responsive pathway?
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
What is a synergistic pathway?
Responds to both androgenic and oestrogenic metabolite of testosterone
Direct testosterone, mediated pathway
Only response to testosterone
Physiological, mechanisms and serotonin
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
Serotonin levels in fish (phases)
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
Serotonin levels, depending on social or solitary environments, aggressive behaviour, and vervet monkeys
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
