1. Intraspecific Competition
…is an interaction in population ecology, whereby members of the same species compete for limited resources.

2. Competition for resources
Intraspecific competition more severe than inter- as individuals are competing for the same resource (food, nest sites, mates).
Competition is damaging to individuals. It promotes physiological stress – poor health, increased risk of disease, increased mortality, decreased natality, overall reduced fitness.

3. Living in groups
Most animals live in groups, few live solitary lives eg some of the cat family – tigers.
Groups are organised and co-operative. Individuals assist one another.
Group maintenance and behaviour are behavioural adaptations – have been selected for as they enhance survival and reproductive success.
Advantages of group living must outweigh disadvantages for group living to continue.

4. Advantages of group living
Protection from physical environment
Greater ability to detect predators
Better defence against predators
Role specialisation eg social insect colonies
Greater ability to find food
Mates available
Assistance with rearing young
Provision of learning opportunities for young
Regulation of population through controlled access to mates/resources

5. Disadvantages of group living
Increase intraspecific competition
Increased risk of spread of disease/parasites
Access to mates may be restricted to only higher-ranked males
Increased risk of infant mortality eg infanticide in lions
Activity: ‘Altruism’ and ‘Kin selection’ notes. Do questions on Co-operative groups.

6. Aggressive behaviour
Competition for resources may promote aggression between individuals.
Especially common between mates during breeding season.
If one/both die, genes lost to gene pool and group loses males needed for group management, protection and breeding.
The stronger/healthier male wins access to a group/females and is ‘fitter’ so contributes a higher proportion of alleles.
Kangaroo boxing

8. Agonistic behaviour
Results in a reduction of aggression within members of a species.
Postures, gestures, vocalisations that threaten an animal are understood and the threatened animal backs off or displays submissive behaviour.
So…serious encounters are rare.
Agonistic behaviour tends to be ritualised – the dominant/submissive postures are recognised by group members.
Limits aggression leading to fatalities.

9. Ritualised postures Dominant postures: Stand erect/large
Head/tail erect
‘eye balling’
Hackles up
Teeth displayed
Vocalisation eg growling

10. Submissive postures:
Stature small/cowering
Belly/throat displayed
Tail down/between legs
Head down/eyes down or averted
Teeth not displayed
Vocalisations (whimpering, whining)
Submissive behaviours are often copies of juvenile behaviours (appease aggressive adults).
Activity – Intraspecific competition and aggression questions . BZ pgs 65-67

11. Territory
A territory is occupied by an animal, which it defends against others.
A home range is a geographical area that animals seldom leave, which is defended.
Animals hold territory through aggressive behaviour.

12. Adaptive features of territoriality
Ensures enough space for each animal
Decreases risk of disease/parasites
Most successful males hold best territory – offspring get best genes
Once territories established, resources are divided. Losers spread out to find food rather than fighting
Ensures enough food
Ensures safe/protected nest/home for young or place to breed
Become familiar with the area. Learns where resources are, and protection from predators

13. Marking and defending territories
Birds – mark territories by singing on boundaries at dawn/dusk
Urine/faeces
Scent glands
Crabs wave claws frantically
Howler monkeys – loudest morning chorus
Nb. Some animals that range far/wide only guard territory during breeding season eg seabirds

14. Hierachies ‘Pecking order’
Hierachies are established competitively.
Once in place, reduces competition and tension in the group.
So who dominates in a group?
larger, more mature
Offspring or not
Knowing the territory/being a stranger
Healthy rather than sick
The dominant has first food, first choice of mate, responsibilities
Dominance is maintained by posture and display.
Activity – Complete ‘Hierachy’ worksheet