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
