Group living and social organisation L3 part 2

Question 1

What is parasocial pathway?

Answer 1

Parasocial pathway - a consequence of individual decisions to live together.

Question 2

What is Quasi-social pathway

Answer 2

Quasi-social pathway- parents keep their young with them to form groups.

Question 3

What happens when such groups exist?

Answer 3

Once such groups exist then more elaborate forms of social interactions can develop. E.g Animal societies- Usually family groups.

Question 4

How does fitness costs effect living in groups?

Answer 4

Living in groups should incur numerous fitness costs (genetic effects in reducing the potential for successful mating and breeding) associated with pathogen transmission and conflicts of differing kinds.

Question 5

What is the functional approach?

Answer 5

The functional approach: Aggregation has evolved because it serves a function.

Question 6

What is the by-product approach?

Answer 6

The by-product approach: groups occur as the by- product of decision-making by many individuals.

Question 7

Define what is a aggregation?

Answer 7

An aggregation is a “skew in animal distributions compared with the idea free distribution”

Question 8

Define Ideal free distribution

Answer 8

Ideal free distribution (IFD)- All individuals in a population have access to the same resources leading to an equal sharing of resources among the population. (very rare in societies)

Question 9

What are the benefits of group living?

Answer 9

Predation mitigation, Finding food, Scarce refuges, modification of the environment, Resource defence, Mate defence and defence against infanticide.

Question 10

What are the costs of group living?

Answer 10

Disease spread, Competition for resources, Disruption to mating and Greater risk of inbreeding.

Question 11

Define Avoiding detecting?

Answer 11

Avoiding detecting (Selfish herd): Individuals hide behind others to reduce chances of being caught usually within a larger group: For example in schooling fish.

Question 12

Define the Diluting individual risk?

Answer 12

Diluting individual risk (Dilution effect): Chance of an individual being selected by a predator are lessened. Works as long as conspicuousness of the group to predators does not increase linearly with group size and the predator only kills one or a few individuals.

Question 13

Define predator confusion

Answer 13

Predator confusion: When hunting predators find it hard to pick out individuals from a group, this is enhanced if the group displays fleeing behaviour and/or amalgamates (merge) into larger groups.

Question 14

What ways have prey developed to detect threat?

Answer 14

Predators are detected better by groups than individuals

Predator or escape responses from others in a group allow animals to take avoiding action

Feeding time is increased in groups as others can take watch

Sentinels are set by some species to watch for predators, taking turns to watch and feed. E.g. Meerkats and Arabian babblers.

Question 15

What is group defence used for and how?

Answer 15

A greater chance of defeating predators than individuals

Mobbing behaviour is characteristic in many species

Mongooses gather round snakes to drive them away

Musk oxen form defensive circles around their calves

Question 16

How does Local enhancement help animals?

Answer 16

Animals are attracted to others that are feeding, or search for food more actively if their neighbours are feeding alone.

Other individuals= food location - if food is abundant there is no sharing cost. (More feeding as a group to be more effective)

If a food clump is discovered and the disperses quickly once predation starts there is no cost of the individual as the resource is time-dependant.

Question 17

Explain information centers?

Answer 17

Colonial grouping provides information centres about ephemeral patches of food. Individuals find these and others then follow but little observational evidence.

Many species fulfil the intellectual and social criteria (E.g. marine pinnipeds), though may be serendipitous (Found by accident) rather than a strategy.

More easy for single individuals in a group to find food by learning from others

Question 18

Explain what are recruitment centres?

Answer 18

Alternative is the recruitment centre: there is a greater benefit in hunting in a group (Vigilance etc) this is called the Allee effect. An individual returns to the communal area because it is likely to recruit conspecifics to forage/ hunt with. The communal area then becomes recruitment centre rather than an information centre.

Once the hunting zone is found recruitment of others to help the individual is undergone.

Question 19

How is time increased for feeding?

Answer 19

A larger proportion of time can be spent on feeding as the group watches for predators

Question 20

How does better group knowledge and find better areas benefit animals?

Answer 20

More individuals in herd/other large groupings provide a better group knowledge about historical distributions of resources.

Works for long-living social animals like elephants, but also for highly cooperative social groups such as ants and bees.

Question 21

Define scarce refuges

Answer 21

Individuals group in some areas due to scarcity of alternative sites. There may be other benefits but one of the prime reasons is lack of other options.

Question 22

Give examples of how groups of animals can cause the modification of the environment

Answer 22

At a simple level the presence of several individuals can make the environment more hospitable, for example wrens in winter.

Most extreme examples are social insects that develop nest that provide very fine scale thermoregulation and humidity control.

Question 23

How does resource defence effect animals?

Answer 23

Defending territories, food resources or mates is normal for many animals at least for some parts of their life cycle. An important reason for the evolution of group living in lions.

Question 24

Define mate defence and defence against infanticide

Answer 24

By the male staying with the group they can protect the group from other males, ensure their paternity and prevent infanticide. Where females carry their young - especially in primates - this may well be significant reason for male - female association.

Question 25

Define disease spread in relation to group living?

Answer 25

Interaction between individuals and living in close proximity = rapid spread of communicable disease.

Question 26

How does competition of resources effect group living?

Answer 26

This can be particularly crucial in times of scarcity

Disrupts social groupings and results in conflict and more interaction with other competitor groups

Can lead to conflicts when resources are limited

Question 27

How does Disruption to mating effect group living?

Answer 27

Complex mating rituals which can be disrupted by other individuals, preventing successful copulation. This chance increases as the group size increases. Promiscuity and mating with multiple partners is fairly common in colonial nesting species.

Question 28

How does the greater risk of inbreeding effect group living?

Answer 28

Relatedness of individuals in a group is likely to be higher thus leading to possibilities for inbreeding.

Question 29

What does group living require to work?

Answer 29

Group living needs cooperation - explains why individuals aggregate into groups.

Question 30

What did Altruistic behaviors evolve to do?

Answer 30

Early work - Altruistic behaviours evolved to restrict, selfish, rapid breeding and therefore prevent outstripping food supplies.

Question 31

What would happen if groups had non-selfish individuals?

Answer 31

Groups with non-selfish individuals would prosper and the behaviour would spread by selection and extinction of selfish groups.

Question 32

Why would individual selection be strong?

Answer 32

individual selection would be stronger force and selfish individuals would ultimately prosper - they would reproduce faster and more often and therefore come to dominate

Question 33

However what has Criticised that group living needs cooperation?

Answer 33

Criticised also since little evidence for this in well-studied groups such as a birds - most of whom reproduce as fast as they could.

Classical Darwinian theory indicates that individuals should behave in ways that maximise their ‘fitness’. (I.e. genetic representation).

Therefore contradiction in working cooperatively or altruistically in a group as there is a genetic advantage to cheating - yet this does not necessarily occur in many social animals.

Question 34

How can individuals improve their fitness?

Answer 34

Individuals can improve their fitness by not only rearing their own offspring but helping other relatives pass on shared copies of genes.

Question 35

Explain the Hamilton’s rule for genetic relatedness

Answer 35

An example: a gene that causes an animal to give off an alarm call will spread, even if the caller is eaten by a predator, provided that:

The caller thereby saves >2 offspring or full siblings (Each of which have one -half chance of containing the gene by common descent).

The caller saves > 4 half siblings (One quarter chance).#

The caller saves > 8 cousins (One eighth chance)

Question 36

What is Kin selection?

Answer 36

This altruistic behaviour towards related individuals is termed Kin selection.

Question 37

In cooperatively breeding vertebrates helpers are often the?

Answer 37

the previous offspring of the breeding pair.

Question 38

Explain Fine-scale and intimate help

Answer 38

Fine-scale and intimate help, e.g. grooming to remove ectoparasites - they spend more time grooming their closest relatives than others.

More straightforward such as being on guard of helping with food collection.

Question 39

Give examples of Extreme Cooperation

Answer 39

1: Cooperation by individuals other than parents in caring for the young.
2: Overlap of at least 2 generations capable of contributing colony labour.
3: Reproductive division of labour with a mostly or wholly sterile worker caste working on behalf of individuals engaged in reproduction.

Question 40

Cooperation is rare in invertebrates, give an example of one?

Answer 40

naked mole rat

Question 41

What is a colonises range in size?

Answer 41

from 20-300 individuals, average 75 individuals.

Question 42

What does it mean by Superorganism?

Answer 42

Naked Mole rat
The complexity in their behaviour and coordinated activity has sometimes earned the ‘superorganism’ label…comparing individuals within a colony with cells within an organism. (E.g. Queen ant)

Question 43

What does Kin selection favour?

Answer 43

Kin selection is therefore favouring related individuals

Simple rules such as ‘treat those near you as kin’ could work when populations are structured so that individuals stay near their birth location and group.

Question 44

What do birds use to discriminate between those whom they have close contact with and not

Answer 44

Social Hymenoptera use nest odour to discriminate.

Question 45

Give an example of Kin recognition

Answer 45

Belding’s ground squirrel - Daughters usually settle near their mothers and that close female relatives were less likely to fight over burrows or territory than unrelated females.

Unrelated females sometimes tried to kill young and were fiercely chased away.

Question 46

Explain Phenotype matching

Answer 46

Phenotype matching - an individual compares phenotypic cues such as odour with the individual’s own cues or cues learned from close relatives.

Question 47

What can Kin selection not explain?

Answer 47

Non-related cooperative behaviour

Question 48

Explain Mutualism in relation to 2 or more individuals working together

Answer 48

Mutualism - 2 or more individuals working together have a greater chance of success, for example cheetah alliances.

This kind of mutualism is called by-product (or short-term) mutualism and is probably a common explanation for much cooperation observed in nature.

Question 49

Explain Reciprocity

Answer 49

Reciprocity - (reciprocal altruism) - as long as the benefits outweigh the costs, the participants can exchange roles and cheaters could be identified and excluded

Question 50

Explain Long-term mutualism

Answer 50

Long-term mutualism: Even if individuals would benefit in the short-term from defecting from the group in the long-term they will benefit because their behaviour will contribute to the survival of the group thus increasing their survival chances through the dilution effect.

Question 51

Explain Coerced cooperation

Answer 51

Some individuals in a group coerce others to cooperate, especially where there is a dominance hierarchy.

Question 52

Explain Ecological constraints

Answer 52

If there is nowhere for the individuals to go, for example a lack of territories, individuals stay and contribute to bringing up young.

If resources are good, young may stay and help out with the next generation and have to be physically chased away.

Question 53

What is a recent trend to see grouping?

Answer 53

A recent trend is to see grouping not as a unique phenomenon but is instead a family of phenomena with no general explanation.

Question 54

Grouping can be seen as a result of different factors: Explain Habitat choice

Answer 54

Habitat choice: Selection favours the ones who can choose the best habitats. Groups form because the best areas are found in one place.

Question 55

Grouping can be seen as a result of different factors: Explain mate choice

Answer 55

Mate choice: Sexual selection plays a vital role in the evolution of group living, they choose to be in a location where they have a better chance of finding a suitable mate.

Question 56

Grouping can be seen as a result of different factors: Explain Habitat copying

Answer 56

Habitat copying: Once clusters of individuals form then those individuals must interact. Individuals that profit from this unavoidable aggregated situation will be favoured by selection and hence groupings perpetuate.

Question 57

Grouping can be seen as a result of different factors: Explain Hidden Leks

Answer 57

Hidden leks: Even in socially monogamous species there is often extra-pair copulations results in aggregations of male-defended territories leading to development of colonial groupings. This ‘secondary mating system’ seen in species such as razorbills.