Part 2 - kin

Question 1

Cooperative breeding is quite widely distributed among animals. … of birds are cooperative breeders (individuals other than parents help raise offspring), … of mammals and over … species of fish (so pretty rare in fish - mainly ….)

Answer 1

4-9%, 3%, 20, cichlids (great rift valley lakes in east africa)

Question 2

The … … hypothesis is composed of two steps, the first being habitat …/ecological constraints, and the second being the fitness benefits of helping … those of not helping (directly and indirectly).

What does this indirect/direct part mean?

Answer 2

ecological constraints (e.g. shortage of habitat, risky reproduction or dispersal), saturation, exceeding

Direct - increase or enhance future survival and reproduction of helper
Indirect - by helping, helper might increase survival or productivity of the helped breeders
- fitness benefits often better than not helping at all

• Independent breeding is constrained –> grown offspring delay dispersal and “stay at home” –> Grown offspring help to rear later broods

Question 3

Estimated that, in species with helpers, if constraints on independent reproduction are relaxed, then helpers will…

Answer 3

disperse from their native territories and take up the opportunity to breed independently (i.e. reduction in helping)

Question 4

Various studies support this,
e.g. in sociable weavers, when additional … was provided, helpers were more likely to breed independently rather than staying at home.

In red-cockaded woodpeckers, the provision of additional … … lead to helpers leaving their natal territory and breeding independently.

In superb fairy wrens, if territories were vacated through the … of …, helper males dispersed to take up these vacancies

These intraspecific studies suggest that indeed constraints are in operation and relaxing them allows more independent breeding.

Answer 4

food (relaxing food constraint)

nest holes

removal, males

Question 5

If we compare cooperative with non-cooperative species, according to the ECH, we’d predict that constraints on reproduction are … in cooperative species than they are in non-cooperative species. This is very obviously not the case. In non-cooperative UK species such as blue tits, magpies and blackbirds, a substantial proportion of these populations are …-… (e.g. … males in blackbirds unable to attract females due to biased sex ratio). Unpaired males never become helpers at the nest. Magpies often take … years before they are able to defend a territory. Those that are waiting to become breeders never become …. Why do non breeders help in some species, but not in others? hmmm

Answer 5

stronger, non-breeders, 20-25%, 2-3, helpers

The question is: can we explain the inter-specific distribution of cooperative breeding?

Question 6

The first thing to notice is that there is a very strong … component to cooperative breeding. For example, there are … species of fairy wren and they’re all cooperative. 25% of Australian corvidae are cooperative (well above 4-9% average). In many group, e.g. seabirds, there are no cooperators.

Answer 6

phylogenetic

Question 7

Looking across the avian tree of life, we can see >… independent transitions to or from cooperative breeding in birds. This is a useful consideration for comparative analyses.

Answer 7

50

Question 8

Hypothesis 1 for explaining the distribution of cooperative breeding across the avian phylogeny: does ecology … independent breeding in some groups, who therefore become cooperative, but not in others, who therefore remain non-cooperative.

Answer 8

constrain

Question 9

There are 45 species of African …. Rubenstein and Lovette (2007) categorised these as either cooperative or non-cooperative breeders. They then looked to see whether cooperation was associated with any particular habitat (savannah vs non-savannah). They found that cooperation was strongly associated with … living.

What is it about savannahs that make them conducive to the evolution of cooperative breeding? Hypothesised that the association was attributed to the … of the environment. Resources vary more through time and space in unpredictable environments so independent reproduction may be difficult - may be better to live in a group rather than disperse independently. Found that predictability and … of savannah habitat significantly lower than in desert or forest habitats. Supported their hypothesis. (and hypothesis 1?)

Answer 9

starling, savannah (all savannah species cooperative, most non-savannah species non-cooperative)

predictability, constancy

Question 10

Is environmental unpredictability associated with cooperative breeding on a global scale?

Answer 10

Proportional richness of cooperative breeders in 9310 species of non-marine birds (as marine birds are all non-cooperative) analysed and found that cooperative breeding is concentrated in certain environments such as Subsaharan Africa and Australia, parts of the middle east etc.

Predictability of environments globally was then measured according to two variables: temperature and precipitation. Measured within years (seasonality) and among years. Matched this up with the prevalence of cooperative breeders

Found that the hypothesis was supported: prevalence cooperative breeding is associated with greater variation in rainfall, both between and among years. However, the association is pretty weak. There is a huge amount of overlap in the types of environment that cooperative and non-cooperative breeders live in.

Question 11

The predictability hypothesis has also been tested in mammals. What was foynd?

Answer 11

Distribution of cooperative breeders (hotspots in east and southern africa and north america) associated with decreased predictability of rainfall AND TEMPERATURE among years, when compared to monogamous breeders.

Again supports hypothesis, but rather weakly.

Question 12

So evidence from analyses of birds and mammals suggests that cooperative breeding is indeed associated with unpredictable environments. But the evidence is not in anyway conclusive. One can also not infer that…

Answer 12

the environment has selected for cooperative breeding. It could be that cooperative breeding allows for colonisation of harsher environments

Question 13

Cornwallis (2017) tested this hypothesis that cooperative breeding allows colonisation of harsher environments and, by looking at the transitions from benign to harsh environments of cooperative and non-cooperative bird species, found…

Answer 13

that the transition from benign environments to harsh environments was much more pronounced for cooperative lineages than it was for non-cooperative lineages.

However there are caveats with this study - predicting environments from ancestral traits is difficult, attributing transitions to particular nodes in the radiation of birds.

(reconstructed and assessed ancestral traits in avian evolution)

Question 14

Overall, evidence from hypothesis 1 that ecology constrains breeding more in some species than others is…

Answer 14

far from conclusive

Question 15

Hypothesis 2 is the idea that it is not external constraints which cause offspring to stay at home, but that there are benefits of … (staying at home) and these benefits select for delayed ….

Answer 15

philopatry, dispersal

Question 16

This hypothesis 2 has been tested in a few species, one of them being the … … in coastal California. In this species, sons usually spend the winter on their natal territory, and may help in the following year. … is a key food resource for this bird during the winter. Access to this is increased by staying at home. Manipulating the availability of this resource by removing clumps of this ….
They found that…

Answer 16

western bluebird, mistletoe, mistletoe

the resource wealth at home and the potential benefits derived from this was a key player in determining whether sons (not daughters or parents) were philopatric or not. (see table on photo on phone).

Question 17

A study into green …, a species in which both sexes may stay at home for several years before dispersing to breed, found that females (but not males) who stay for a while have higher … (goes against ecological constraints hypothesis). This study suggests that philopatry may be … rather than forced by external constraints.

Answer 17

woodhoopoes, LRS, beneficial (e.g. better parents, acquiring helpers or territory)

Question 18

Some authors have argued that there isn’t much difference between the idea of ecological constraints n dispersal and benefits of staying. In both cases, offspring must weigh up the relative benefits of staying against those of dispersal. The ecological constraints hypothesis (hyp 1) and the philopatric benefit hypothesis (hyp 2) really differ only on the emphasis placed on..

Answer 18

the pros and cons of staying and/or leaving

• nevertheless, looking across taxa, the preponderance of evidence seems to be in support of the idea of constraints rather than benefits of staying.

Question 19

Hypothesis 3, one of the main competitors of the ECH is the idea that … … traits predispose some lineages to cooperate.

Answer 19

life history

Question 20

This idea fits very nicely with the distribution of cooperative breeding through the avian phylogeny. It is very patchily distributed in certain families. The argument goes that those taxonomic lineages with slow life histories appear to…

Answer 20

have a low rate at which breeding vacancies arise - in those lineages we see the evolution of cooperative breeding

Question 21

What do we mean by slow life histories?

Answer 21

• increased longevity
• decreased clutch size
• migration

these are all associated with a slow rate at which breeding vacancies open

Question 22

This idea was tested by Arnold. In a comparative analysis she looked across the global avafauna and identified those families with slow vs fast life histories. She found that..

Answer 22

in those families that were long-lived with small clutches, cooperative breeding was clustered. Argued that cooperation was more likely to occur in these low fecundity taxonomic lineages. In those families with a fast life history (short lived, high turnover rate, large clutches), cooperation was never found, no matter the ecological conditions. This supports the life history hypothesis.

Question 23

It has since been pointed out that these particular sets of life history traits are not only associated with cooperation or non-cooperation, but were also associated with…

Answer 23

tropical and temperate regions of the globe. So it could be that it is not the life history traits themselves that drive the evolution of cooperation, but rather the environments that the birds live in.

Slow life history –> more likely in tropical regions like subsaharan africa, australia

Fast life history –> more likely in temperate regions

Problem - very hard to distinguish life history from phylogeny and biogeography etc. they all appear to be wrapped up together.

Question 24

Hypothesis 4 is that cooperative breeding may be associated with … ….

Answer 24

brood parasitism

Question 25

There are two potential relationships going on here with hypothesis 4.

The first is that brood parasites (such as bronze cuckoos) may want to target cooperative breeders because…

The second is that, from the host’s point of view…

Answer 25

there are more carers at the nest who may provide more food for the offspring than would a simple pair (may be beneficial for survival of offspring, who are often much larger than host)

having helpers may improve their defence against the cuckoos/brood parasites (more pairs of eyes etc.), so having more helpers selected for when brood parasitism is common.

Question 26

This idea was first tested in the specific context of the Horsfield’s bronze cuckoo vs the superb fairy wren. It was found that the mass of parasite chicks and likelihood of fledging…

Secondly, the idea that parasitism selects for cooperative breeding was tested by looking at the amount of time spent mobbing cuckoos when they approached the nest in small vs large groups. It was found that…

Answer 26

were higher in nests where there were helpers than in nests where there were no helpers - so parasites prefer cooperative breeders

time spent mobbing was significantly greater in larger groups than in small groups and the proportion of nests that were parasitised in large groups was significantly smaller compared to small groups - supports idea.

Question 27

The global distribution of cooperative breeding is also associated with…

Answer 27

the distribution of obligate brood parasites

Question 28

In African and Australia, hosts of brood parasites are…

Answer 28

more likely to be cooperative breeders, though the direction of association is unclear.

Question 29

So none of the 4 hypothesis are conclusive as predictors of sociality. Why is predicting sociality so difficult?

Answer 29

• cooperative breeding includes many diverse social systems which differ in complexity (catch all phrase)
• constraints (which may be selecting for cooperation) are diverse - food, nest sites, territories, mates etc.
• phylogeny, biogeography and life history traits covary

The debate continues…. DUN DUN DUNNN

Question 30

Kin selection is a selection that operates on…

Answer 30

traits due to their beneficial effects on the fitness of relatives

Question 31

What may the direct fitness benefits of helping be?

Answer 31

i) Current reproduction (laying eggs (F) or sneaking extra-
pair paternity (M)
ii) Increased future reproduction
- aquisition of skills/mate/territory
- group augmentation (better survival in larger group
and future help.

Question 32

What may the indirect fitness benefits of helping be?

Answer 32

Increased fitness of relatives:

• better productivity
• better survival of breeders (as less cost to them)

Question 33

To answer the question of how important kin selection has been in the evolution of social systems, we will first look at the major evolutionary transitions in the history of life on earth, all of which involved a degree of cooperation. These transitions are:

• the origin of chromosomes
• the origin of …
• the origin of …
• the origin of multicellularity
• the origin of … groups
• the origin of human …/…

Answer 33

eukaryotes, sex, social, society/language

Question 34

We will now focus on the origin of social groups. This problem was first addressed in social ….

Answer 34

insects

• eusociality = “true sociality”, with non-reproductive castes - e.g. wasps, bees, ants (hymenoptera), termites (isoptera), naked mole-rat

Question 35

Why should some individuals join together to become mutually dependent? The hypothesis derived from inclusive fitness theory is that…

This idea has lead to the proposal of the … hypothesis:
Strict lifetime … results in individuals who are equally related to offspring and siblings (both r = …). Any small net benefit from raising siblings rather than offspring will favour cooperation and potentially eusociality.

Answer 35

high relatedness between individuals played a key role in the transition to eusociality

monogamy, monogamy, 0.5

(leaving to raise own offspring may be far more risky and therefore costly)

Question 36

The more promiscuous a mother is, the less…

Answer 36

related her offspring are to each other (on average)

Question 37

The monogamy hypothesis makes two simple predictions:

Answer 37

i) all eusocial species passed through a “monogamy window”

ii) multiple mating MAY evolve later, following specialisation

Question 38

These predictions were tested by hughes at el (2008). How?

Answer 38

Looked across hymenoptera, identifying monogamous and polyandrous lineages. All eusocial lineages have passed through a “monogamy window” during their ancestral history. Some remain monogamous, while others have transitioned to polyandry (but workers had already specialised for helping).

Question 39

As with multicellularity, the transition from non-social organisms to eusociality can be explained by..

Answer 39

high relatedness, in this case determined by strict lifetime monogamy

Question 40

Does the monogamy hypothesis apply to other taxa? Let’s first look at the mammals. Looking at … … (proportion of offspring produced by the most successful individual within a group), we find that this is much stronger in … mammal species. In …-… species, where there is relatively low …, lots of individuals are contributing to reproduction. Monogamy in these groups is relatively ….

Answer 40

reproductive skew, cooperative (monopolised by one dominant individual - lots of individuals not reproducing), non-cooperative, skew, unusual (instead degree of promiscuity likely)

• supportive of monogamy hypothesis

Question 41

How about in birds? Promiscuity (extra-pair paternity) is…

Answer 41

significantly higher in non-cooperative species. Monogamy is more prevalent in cooperative species

• supportive of monogamy hypothesis
• not as absolute as seen in insects, as still some degree of promiscuity in cooperative species

Question 42

So high relatedness may well have also played a key role in the evolution of social behaviour in…

Answer 42

birds and mammals (though not as convincing)

Question 43

If this is the case (kin selection critical to evolution of cooperative breeding), when we look across bird phylogeny we should expect kin groups to…

Answer 43

dominate among cooperative lineages

Question 44

Data collected from 55 cooperative avian families (comprising 644 species overall). … of these avian families and … of these species cooperate in groups comprised of kin. The rest cooperate in groups comprised of non-kin. (Hatchwell 2009)

Answer 44

82%, 92%

-> kin groups predominate among cooperative breeders
(exceptions are generally cooperative polygamists where all individuals attempt to breed)

Question 45

Why is kinship important to the evolution of cooperative breeding?

Answer 45

Kin-selected helping is a key route (among birds).

Question 46

In white-fronted bee eaters, increasing the group size increases…

Answer 46

the average number of fledglings per nest (productivity)

• lots of studies like this, this is only one example

Question 47

However, confounding effects of … or … … had not been accounted for. If there is a positive relationship between group size and productivity (e.g. in laughing kookaburras), one explanation is that the presence of helpers increases productivity. However, this is not necessarily the case. It could be that pairs living in high quality territories are very productive, and therefore produce more helpers, or simply higher quality pairs produce more helpers. This must be controlled for in order to truly assess the effect of helpers on productivity

Answer 47

territory, individual quality

Question 48

This test was carried out in laughing kookaburras by Legge (2000), and she compared productivity within the same territories with different numbers of helpers in different years (controlling for quality of territories). Found that…

Answer 48

there was no change in number of young fledged relative to years when there were fewer male helpers, so there was no benefit to adding male helpers. Adding female helpers actually lowered the number of young fledged.

• goes to show that quality of territory/pair MUST be taken into account when assessing the effect of helpers on productivity

Question 49

Another criticism for the view that kin selection allows cooperative breeding systems to evolve is the fact that direct benefits of helping are…

e.g. study of superb fairy wrens found that…

Answer 49

routinely underestimated

extra-pair-paternity occurs at a very high rate (72% of offspring) - indirect fitness benefits becomes much lower and a much harder calculation to make. Females are very cryptic when making these EP copulations.

Question 50

Seychelles warbler - helpers are usually … and were assumed to be …-… and close kin (r = 0.5). So kin selection was assumed to be important for the evolution of cooperation in this species. In reality, … of subordinate helpers reproduce (lay eggs in dominant female’s territory) and … of young raised resulted form EPP. It was calculated that the kinship of helpers to brood was very low at r = ….

The role of kin selection (importance of indirect fitness) was completely reevaluated. In this species, … fitness is much more important than ….

Answer 50

females, non-reproductive, 44%, 40%, 0.13

direct, indirect

Question 51

A sceptic’s view of evidence for kin selection leading the the evolution of coooperation:

1. Confounding effects of …/individual …
2. … benefits of helping underestimated
3. Costs of kin … ignored
4. We should see abundant evidence for active kin ….

Answer 51

territory, quality (control for statistically or experimentally)

direct (need genetic analyses of relatedness)

competition (many studies of intra-familial conflict)

discrimination (i.e. not helping unrelated broods, closely related helpers working harder etc.) (good evidence for now)

Question 52

This fourth criticism prompted people to go out and look for such active kin discrimination (criticism useful).

Since then, quite a lot of evidence for this has accumulated. One example is in … ….

Answer 52

Bell miners

Question 53

Researchers looked at bell miner nest … rate (a measure of investment contributed by helpers) in relation to the level of … to the brood being cared for. They found that…

Answer 53

visitation, relatedness

those helpers that were distantly related to the brood invest less than those who are more closely related. This is evidence for active kin discrimination.

Question 54

Meta-analysis of kin discrimination within species shows…

Comparative analysis of helper effort across 37 species (controlling for phylogenetic relationships) found that…

Answer 54

significant kin discrimination across studies

helper effort was significantly positively related to the kinship of helpers to the brood - consistent with Hamilton’s rule

Question 55

How important is kin selection for evolution of cooperative breeding systems in vertebrates?

Circumstantial evidence is …

Single-species studies show … evidence

How important is indirect vs direct fitness?

Answer 55

strong (we see cooperation evolving predominantly among kin groups)

strong (we can identify examples where kin selection has been pivotal in the evolution of helping behaviour

This is clearly variable across species
(e.g. kinship very important in Florida scrub-jays and white-fronted bee-eaters, kinship not so important in superb fairy wrens and seychelle warblers, sometimes mix of primary and secondary helpers e.g. in pied kingfishers - look up more if want. In some cooperative species, helping behaviour occurs among non kin, e.g. dunnocks, groove-billed ani - cannot be indirect fitness benefits)

Question 56

… systems are of fundamental importance at every level of biological organisation

Answer 56

recognition

e.g.
transcription of DNA (requires recognition of base pairs etc.)
Communication among cells - recognise self from non-self
Social insects - distinguish colony members from those of other colonies

Question 57

Adaptive decisions about mate choice, cooperative investment, social affiliation etc. depend on … ability, hence recognition systems

Answer 57

discrimination

Question 58

Kin recognition is..

Answer 58

the differential treatment of conspecifics differing in genetic relatedness

Question 59

(Kern Reeve’s model) An actor wishes to cooperate with a recipient. He is faced with a number of potential recipients within the population. He must decide who to cooperate with. The potential recipients produce …. Say one potential recipient produces a red cue and another produces a blue cue. These are … by the actor, who then compares them with a …. In this case, the template possessed by the actor is also red. There is a close match between the cue produced by the first potential recipient and the actor’s template, which triggers an action component (cooperation) in the actor, which benefits the recipient.

If a third potential recipient has a purple cue, should the actor act cooperatively to this third individual? This is the problem reeve adressed in his model

Answer 59

cues, perceived, template

Question 60

(Reeve’s model (1989)). Watch slides 6-16 lecture 9 - too complex to write everything down.

Answer 60

go on then! (acceptance thresholds and stuff, rejection and acceptance errors)

Question 61

Generous strategy = many … errors, few … errors

Conservative strategy = many … errors, few … errors

Answer 61

acceptance, rejection (e.g. if low cost:benefit ratio - being cooperative not very costly but large benefit)

rejection, acceptance (e.g. if high cost:benefit ratio - cooperation very costly)

Question 62

We think this generous strategy might be occurring in long-tailed tits. Some helpers (over 1/5) assist non-kin even though it confers no direct (or indirect) fitness benefits. This is because help is … and the kin-selected benefits are potentially large. Therefore it is a good strategy to be generous with help in these birds.

Answer 62

cheap (already unable to breed, might as well help)

Question 63

Evidence for the acceptance threshold model: Honeybees. Honeybee hives post … at the entrance to the nest. They prevent bees from other colonies from coming in and stealing nectar/honey. These … must inspect every forager returning to the hive. If they do not recognise them, they attack them. The intruder either flies away or is killed. The behaviour of … at the entrance to honeybee hives should depend on…

Answer 63

guards, guards, guards, the cost of robbery by intruders.

Question 64

The hive changes in weight during a season, due to the amount of honey/nectar stored in it (when most flowers start blooming in spring, the amount of nectar available shoots up, and so does the wight of the hive). Predicted that when the hive weighs less, there is … honey in the hive so it is a more … resource and guards will be more … with their discrimination than when the hive is heavier and there is … honey stored in it.

Was this the case?

Answer 64

less, valuable, conservative, more

Yes. Fewer guards, fewer fights at hive entrance, and increased acceptance into the hive observed later in the season (when there is more honey) - increased generosity later when costs are lower.

Question 65

Genetic cues to kinship: … theory (Dawkins 1976). An actor may carry a recognition allele that … itself, … itself and directs … towards bearers.

Answer 65

greenbeards, signals, recognises, cooperation

Question 66

Greenbeard gene identified by Keller and Ross (1998) in … …

Answer 66

fire ants

Question 67

All egg-laying females are Bb at locus …-….

• bb females die prematurely from intrinsic causes
• BB queens that initiate reproduction are killed by Bb workers

Recognition occurs via … ….

Answer 67

Gp-9, odour cues

• so locus can recognise itself (odour cues), discriminate between carriers and non-carriers, and act upon this recognition (by killing)
• actually a greenbeard social chromosome

Question 68

Why may there be few greenbeard genes in nature?

Answer 68

Can be easily exploited by “falsebeards” - signals greenbeard without paying the cost of cooperation with other greenbeards.

Other genes may supress expression of greenbeard behaviour if it is not to the advantage of other genes within the genome

Question 69

Although there is not much evidence for green beard genes, there is good evidence that genetic cues to kinship can work by the possession of markers that indicate gene sharing - dubbed the … effect. This is because the most likely complex of genes to indicate gene sharing are … genes

Answer 69

armpit, MHC

Question 70

Studies of arctic char (fish) and African clawed toads have shown that juveniles discriminate among siblings, preferring…

Answer 70

the odour of those with the same MHC genotype

Question 71

Armpit effect in mice: Mouse … … (MUPs) - inherited as a haplotype of tightly linked genes (like MHC).

In an experiment, a subject female was put in a neutral cage and allowed to move between cages, one of which housed a sister or an unrelated female. Their movement was monitored remotely. The focal female…

Answer 71

urinary proteins

spent much more time with their related sister
controlled for familiarity

Question 72

In a second experiment, female mice preferred to associate with unfamiliar females that shared their own … type but not their … type. This was related to … cues, as whether the room was light or dark made no difference to the result. These results indicate …-… phenotype matching of the … genotype.

Answer 72

MUP, MHC, odour, self-referent, MUP

Question 73

Environmental cues to kinship: a “rule of thumb” may be a sufficiently reliable cue of kinship. For example … cues: e.g. “feed anything in my nest/territory” - high probability that will be own offspring, no complex genetic mechanism required. Though this might be exploited, e.g by … … - work well in some contexts, not so well in others.

Answer 73

spatial, brood parasites.

Question 74

Bank swallows nest in large colonies, each pair having dug an individual burrow in which the chicks are raised. Once the chicks have fledged, the parents must learn to discriminate between their own offspring and that of others, without depending on the spatial cues provided by the location of their nest. The young leave the nest at around … days old. If you switch chicks around between nests, up until around … days, parents will happily accept any chicks - clearly using spatial cues (probably their own offspring. From … days onwards, parents become fussier (fewer transfers accepted). During this time, chicks develop … …, which the parents learn to recognise. Switch from … cue to learned … cue.

Answer 74

18, 15, 16, signature calls, spatial, vocal

Question 75

… cues seem to be widespread in nature (‘treat anyone i was reared with as kin’ or ‘treat anyone who sounds/smells like me as kin’)

e.g. … odour in social insects (characteristics of wax or nectar or honey within hive - guards use to discriminate)

Answer 75

learned, colony

Question 76

Learned kin recognition is also important in long-tailed tits - … cues (churr calls and triple cues)

• individually …
• highly …
• family resemblance
• adults discriminate kin from non-kin

These calls are … rather than … ….

Interestingly, helpers that help non-kin (~20%) may do so because…

Answer 76

vocal,
distinctive,
repeatable (sound same throughout lifetime)

learned (from parents), genetically inherited

they sound like kin

Question 77

There is significant active kin discrimination across bird studies, but what i did not mention before is that the discrimination level is..

Answer 77

very variable

- in some species there is very little kin discrimination

Question 78

It’s not necessarily the case that kin selection is unimportant in these studies. When level of kin discrimination is measured as a function of relatedness to potential recipients, those species with a higher likelihood of relatedness to potential recipients generally showed lower kin discrimination (e.g. kookaburras - live in highly related groups so high likelihood that feeding any young will be kin - complicated mechanisms of kin discrimination not necessary)

Active discrimination of kin evolves only when adaptive (i.e. necessary)

Answer 78

Good science right there

• kin discrimination evolves when required

Question 79

Kin recognition is probably usually … rather than …

Answer 79

environmental, genetic

Question 80

Mechanism and effectiveness of recognition varies depending on … … and ….

Answer 80

selection pressure, context