Eusociality and Social Systems Flashcards
What are the costs of group living?
Competition for resources and parasite/disease transmission
What are the benefits of group living?
Increased rates of prey capture/improved foraging, defense against predation, collective decision making
How can groups reduce predation?
Predator saturation, dilution effect, confusion effect, alarm calls
What conditions are needed for predator saturation to work? Why are these conditions essential for this to work?
For example, synchronous hatching must be brief or prolonged intervals between events. Under these conditions predator populations cannot increase to the point that they can consume all prey.
What is the dilution effect?
Being in a group reduces the chances that any given individual is the target of an attack. Selfish herd is a term used with dilution effect.
What is the confusion effect?
Large groups of identical individuals provide little information to predators trying to strike. Detectability of individual prey is decreased.
How can we distinguish between the dilution and confusion effect?
Dilution effect: reduce risk of capture for individual prey per predator attack and may increase detection of prey. No effect on success of attacks.
Confusion effect: reduce total number of prey captured and decrease success of foraging attempts, attacks are less successful.
What are alarm calls?
Animals signal about the presence of a predator. Allows receivers to mount a defense. This only works if others are around to receive the signals. Increased collective vigilance is another anti-predator benefit of group living.
What is an example for collective decision making?
Ant colonies outperforming individuals when a sensory discrimination task is difficult.
What are the types of social helping behaviors?
Mutualism, reciprocity, altruism
Mutualism
Immediate direct fitness benefit for both
Reciprocity
Delayed direct fitness benefit for both
Altruism
Fitness benefit for the receiving group member, but direct fitness cost to self
Under what conditions could altruism evolve?
Nest is valuable, dispersal is dangerous, scarce or patchy resources, difficulty finding mate, opportunities for inclusive fitness
What are the characteristics of eusociality?
Adults live in groups, cooperative care for young, reproduction by few, and generations overlap
What defines primitive eusocial species?
Conflict about who reproduces within the group and no morphological difference between reproductives and non-reproductives
What defines advanced eusocial species?
Limited conflict about who reproduces and morphological specialization in reproductives (workers may even lose their ability to reproduce)
The evolution of eusociality can be influenced by…?
Resource distribution and predictability, predation pressure, and kin selection
Division of labor: How are tasks distributed among workers?
By age, morphology, and by genotype
Why is division of labor important?
Important for colony-level function
Division of labor by morphology example
Head width on ants determines what their jobs are. A large head would cut and retrieve vegetation
Division of labor by size-age interaction example
Young ants that are small will work in nursing for half their life and then move onto nest work and foraging the last half of their life. A larger younger ant will spend a little of their life nursing and then quickly move to defense.
Collective intelligence key concepts
Coordination without central control, knowledge distributed among leaderless individuals. Simple individuals following simple rules will arrive at solutions to complex problems. Recruitment is important way to share information. Individuals often weigh social information and environmental information to make a decision, individual decisions add up to tip the colony’s decision.
Superorganisms examples
termites, honeybees, and ants
Stigmergy
A mechanism of coordination where the action from an individual stimulates the same action in another individual, typically through traces in the environment
Probability of recruitment depends on?
Quality of the food source… how good is this food? how eagerly do my nest mates offload me?
