Eusociality and Social Systems

Question 1

What are the costs of group living?

Answer 1

Competition for resources and parasite/disease transmission

Question 2

What are the benefits of group living?

Answer 2

Increased rates of prey capture/improved foraging, defense against predation, collective decision making

Question 3

How can groups reduce predation?

Answer 3

Predator saturation, dilution effect, confusion effect, alarm calls

Question 4

What conditions are needed for predator saturation to work? Why are these conditions essential for this to work?

Answer 4

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.

Question 5

What is the dilution effect?

Answer 5

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.

Question 6

What is the confusion effect?

Answer 6

Large groups of identical individuals provide little information to predators trying to strike. Detectability of individual prey is decreased.

Question 7

How can we distinguish between the dilution and confusion effect?

Answer 7

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.

Question 8

What are alarm calls?

Answer 8

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.

Question 9

What is an example for collective decision making?

Answer 9

Ant colonies outperforming individuals when a sensory discrimination task is difficult.

Question 10

What are the types of social helping behaviors?

Answer 10

Mutualism, reciprocity, altruism

Question 11

Mutualism

Answer 11

Immediate direct fitness benefit for both

Question 12

Reciprocity

Answer 12

Delayed direct fitness benefit for both

Question 13

Altruism

Answer 13

Fitness benefit for the receiving group member, but direct fitness cost to self

Question 14

Under what conditions could altruism evolve?

Answer 14

Nest is valuable, dispersal is dangerous, scarce or patchy resources, difficulty finding mate, opportunities for inclusive fitness

Question 15

What are the characteristics of eusociality?

Answer 15

Adults live in groups, cooperative care for young, reproduction by few, and generations overlap

Question 16

What defines primitive eusocial species?

Answer 16

Conflict about who reproduces within the group and no morphological difference between reproductives and non-reproductives

Question 17

What defines advanced eusocial species?

Answer 17

Limited conflict about who reproduces and morphological specialization in reproductives (workers may even lose their ability to reproduce)

Question 18

The evolution of eusociality can be influenced by…?

Answer 18

Resource distribution and predictability, predation pressure, and kin selection

Question 19

Division of labor: How are tasks distributed among workers?

Answer 19

By age, morphology, and by genotype

Question 20

Why is division of labor important?

Answer 20

Important for colony-level function

Question 21

Division of labor by morphology example

Answer 21

Head width on ants determines what their jobs are. A large head would cut and retrieve vegetation

Question 22

Division of labor by size-age interaction example

Answer 22

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.

Question 23

Collective intelligence key concepts

Answer 23

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.

Question 23

Superorganisms examples

Answer 23

termites, honeybees, and ants

Question 24

Stigmergy

Answer 24

A mechanism of coordination where the action from an individual stimulates the same action in another individual, typically through traces in the environment

Question 25

Probability of recruitment depends on?

Answer 25

Quality of the food source… how good is this food? how eagerly do my nest mates offload me?