Lecture 9 - mechanisms of kin recognition Flashcards
what do adaptive decisions about mate choice, cooperative investment, social affiliation depend on?
discrimination ability, hence recognition system
define kin recognition
differential treatment of conspecifics differing in genetic relatedness
describe the general recognition theory
- Actor compares cue against template
- Actor comes in contact with 2 potential recipients and has to decide who to cooperate with
- Each recipient has a ‘cue’ known as a production component
- Actor has perception component ‘template’
what are 3 key components of a recognition system
(i) Production component – the cues (labels) in recipients that allows actors to recognize them.
(ii) Perception component – the sensory detection of cues by actors and subsequent phenotype matching of that cue to a template of desirable (fitness-enhancing) or undesirable (fitness-reducing) recipients.
(iii) Action component – the action performed that depends on the similarity between the actor’s template and the recipient’s cue.
describe the acceptance threshold model
argues that the cues of desirable and undesirable recipients are likely to overlap, and that actors should have a threshold for acceptance/rejection that optimizes the balance of accepting undesirable recipients and rejecting desirable ones
-Therefore, in any recognition system you can’t expect 100% accuracy
Different strategies have different placing of the acceptance threshold - what are the 2 strategies?
1) ‘Generous’ strategy- many acceptance errors, few rejection errors, e.g. low cost:benefit ratio - not too bad have more acceptances if ratio is low
2) ‘Conservative’ strategy- few acceptance errors, many rejection errors, e.g. high cost:benefit ratio
describe the general understanding of the threshold model
- The understanding is that helping of non-relatives is just mistakes in recognition
- Some helpers assist non-kin even though it confers no direct fitness benefits
- help is cheap, kin-selected, benefits large- E.g Is thought long tailed tits are very generous in helping with care because the cost of helping is low
what is the issue with the threshold model?
useful model in many ways but is difficult to test
what is evidence for the acceptance threshold model?
- Honeybees set guards at the front of their hives and scrutinise every arriving bee at their colony
- They do this because honeybees will raid colonies - guards prevent this
- When you look at the variation in guarding behaviour over a period of time
- Fewer guards, fewer fights and more generous acceptance threshold as food availability increases
mechanisms of recognition can be genetic or environmental what is an example of a genetic cue to kinship?
greenbeard genes - Dawkins 1976
what is a green beard?
a Recognition allele that: signals itself
recognizes itself
directs cooperation towards bearers
examples of greenbeards are rare - give one example
- GP-9 locus in fire ants
- All egg-laying females are Bb at locus Gp-9
- bb females die prematurely form intrinsic causes
- BB queens that initiate reproduction are killed by Bb workers
- Some circumstantial evidence that recognition was driven by odour cues?
- Subsequent work has shown the GP-9 gene isn’t just one locus greenbeard ‘gene’ is a social chromosome, recombination is suppressed by inversion, 616 genes in non-recombining region - but still does act as a greenbeard gene
what is the ‘armpit effect’
- markers that indicate gene sharing
what is a good example of the armpit effect
e. g. Mouse Urinary Proteins (MUPs) - inherited as haplotype of tightly linked genes, like MHC
- Females prefer to associate with unfamiliar females that shared their own MUP type, but not MHC type. Results suggest ‘self-referent phenotype matching’ of MUP genotype.
- Even with no visual cues i.e. in dark - they still made same preferences
what are 2 examples of environmental cues to kinship
1) spatial cues
2) learned cues
describe a spatial cue
e.g. ‘feed anything in my nest/territory
• rule may be exploited by inter- and intra-specific brood parasites
• may not be sufficient e.g. Bank swallow - young in nest until 18 days old - parents accept chicks switched between nests up to 15 days - signature call develops at 15-17 days- parental recognition based on signature calls
describe a learned cue
e. g. ‘treat anyone I was reared with as kin’ or ‘treat anyone who sounds/smells like me as kin’
e. g. ‘colony odour’ in social insects - all smell similar to each other - guards check foragers for this outside hives
describe learned kin recognition in long-tailed tits
Calls allow discrimination of kin from non-kin
- individually distinctive
- repeatable
- family resemblance
- adults discriminate kin from non- kin using those calls
describe the study to demonstrate if the calls are genetic or learned in the long tailed tits
Nestlings learn calls from parents
- so ‘siblings’ have similar calls
- Cross-foster Experiment - Fostered nestlings learn calls from carers so foster siblings have similar calls and sound like foster parents
describe the experiment to understand recognition in king penguins
Playback experiments to chicks using modified parental calls
Showed that chicks use frequency modulation, especially the shape of syllables for recognition
when does active discrimination of kin evolve?
only when adaptive i.e when necessary
kin discrimination occurs in systems where it is hard to recognise and a higher possibility to care for kin by accident that aren’t related - when they stay In the same territory all their lives it isn’t as important - more likely to be related
summarise 4 key points of key recognition
- Recognition errors are inevitable and their frequency depends on relative costs and benefits
- Kin recognition does not require genetic cues of kinship – cues are usually environmental
- Errors are likely even in kin-selected systems
- Mechanism and effectiveness varies depending on selection pressure and context
