Wk 2: Group Living Flashcards
Why do animals live in groups?
- dilution of predation risk
- increased predator detection ability
- increased ability to defend resources
- increased ability to detect & catch food
Cooperative behaviour directed towards relatives may evolve through a process called…
Kin Selection
What is Reciprocal Altruism?
individuals reciprocate cooperative acts
What is Mutualism?
individuals benefit from apparent cooperation
What are the routes cooperative behaviour can evolved into?
kin selection
altruism
mutualism
Negatives of living within a group
- competition can result in overt & damaging aggression
- increased conspicuousness to predator/prey
- increased risk of disease/parasitism
- competition between group members
What mechanisms exist to minimise overt & damaging aggression within groups?
dominance hierarchies
assessment approach
Dominance relationship
where one individual has priority of access to resources over another
What does a dominance relationship within a group give rise to?
Dominance hierarchy
What is an individuals position in the hierarchy refer to as?
Dominance rank
Types of hierarchy
Linear and non-linear
Downside of hierarchy relationship
Low-ranking individuals may suffer a variety of costs
Summary of Dominance Hierarchy
- may be specific to one situation/resource
- low rankers usually incurs more costs
- may exist with minimal aggression once hierarchy is formed (dispute settled on basis of rank)
Assessment
the ability of individuals to assess their relative fighting/competitive capabilities and resolve disputes on the basis of their assessment
Pros of Assessment
this may allow individuals to assess conflict without overt damage or aggression
How is group living flexible?
emigration and immigration can occur when pay-off of living in a group outweigh those of solitary living and vice verse
(individuals cannot defend resources/ when within-group competition is high_
With group living be flexible, what can emigration constrain?
acts to constrain over-despotic behaviour by dominants
How is flexibility of group living continue in domesticated species?
single and multi-cat household with others (back-yard chickens and pigs) forming groups similar sized to those in their previous species
Why is knowledge of the basic principles and concepts of group living useful for animal welfare?
can consider the constraints on group-life caused by captivity, and their implications = animal welfare
Some common constraints on group structures/behaviours
- group size, density & composition
- clumped/limited resources
- no voluntary escape options
- rapid enforced (& repeated) mixing of animals
Effects pf clumped/limited resources on group living
Low ranking animals may have restricted access to areas if dominants can block key walkways/monopolise clumped resources
How may resources be clumped?
Space & Time
Consequence of groups of one and who does it effect?
removes benefit of social contact
(dogs, horses & boars)
Consequence of very large groups and who does it effecr?
failure to recognise individuals
lack of cooperation/stable hierarchy
(chickens. fish & pigs)
Consequence of same-sex or same-age groups and who does effect?
increases similarity in group members; hierarchy less stable
(pigs, dairy calves, chickens)
