BIOL3046 Lecture Notes - Lecture 6: Reciprocal Altruism, Cleaner Fish, Data Visualization
5 Jul 2018
School
Department
Course
Professor
Animal Behaviour BIOL3046 460381099
Lecture 6: Social behaviour in non-related individuals.
• Possible reason for grouping between unrelated individuals will be discussed. Animals
only form groups if they gain individual advantage, that is 𝑟 𝑋 𝐵 > 𝐶.
Selfish herd: When danger occurs it is often safer to escape and move closer towards
similar individuals. Thus, these aggregation over time will form groups.
Reduces the animals domain of danger (DOD), in turn reducing the predation
risk. Individuals on the edge of groups don’t always have the greatest DOD,
as it can be confounded by other factors such as body shape, colour, sex etc.
Example: Fake seals of the same body shape etc. were put in the ocean with
varying DOD. Sharks were more likely to attack those with greater DOD. Also
known as the dilution effect.
Vigilance: More individuals to sense potential danger. Example: Meerkats.
Many eyes: Grazing animals can’t look up when eating. Example: Elk.
Confusion: Predator gets confused and doesn’t know where a single animal is. Example:
Zebra.
Mobbing: Pressure to predator. Example: Group of birds.
Pursuit: Deterrence of pursuit, “we have seen you”. Example: Water buffalo.
Parasitism: Fitness of a new group member increases while fitness of a whole group
decreases. Example: Lion joining a group increases its personal fitness
because it can catch prey easier, however new group has to share food with
more individuals so its fitness is reduces. There is an optimal group size.
By-product mutualism: When offspring stay with parents and both benefit. Example:
Cichlid fish stay with parents in safe breeding area, but will help by
feeding offspring.
Reciprocal altruism: Two or more individuals exchange beneficial acts in return. Example:
Chimpanzees form an alliance so one distracts the alpha male while
the other mates with a female. They then reverse roles the next time.
Generalized reciprocity: All individuals contribute to some common good from which
all group members benefit. Example: Weaver birds build common
nests to protect the community eggs from snakes; Cleaner fish.
Document Summary
Lecture 6: social behaviour in non-related individuals: possible reason for grouping between unrelated individuals will be discussed. Animals only form groups if they gain individual advantage, that is >. Selfish herd: when danger occurs it is often safer to escape and move closer towards similar individuals. Thus, these aggregation over time will form groups. Reduces the animals domain of danger (dod), in turn reducing the predation risk. I(cid:374)di(cid:448)iduals o(cid:374) the edge of groups do(cid:374)"t al(cid:449)ays ha(cid:448)e the greatest dod, as it can be confounded by other factors such as body shape, colour, sex etc. Example: fake seals of the same body shape etc. were put in the ocean with varying dod. Sharks were more likely to attack those with greater dod. Many eyes: grazi(cid:374)g a(cid:374)i(cid:373)als ca(cid:374)"t look up (cid:449)he(cid:374) eati(cid:374)g. example: elk. Predator gets co(cid:374)fused a(cid:374)d does(cid:374)"t k(cid:374)o(cid:449) (cid:449)here a si(cid:374)gle a(cid:374)i(cid:373)al is. Fitness of a new group member increases while fitness of a whole group decreases.
