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NROC34 Lec 7.docx

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University of Toronto Scarborough
Karen Williams

NROC34 Lec 7  Why live in groups? o Living in a society is complex – need many cues and need to be able to read them and respond to changes o Being able to recognize the group is important for group living o 2 instances where you might need to:  Foraging  Kin recognition  Kin recognition in wasps, squirrels, elephants o Learning, memory might be important o Changes in cues that might happen  could happen through a change in social interaction  Why recognize friend or foe? o Cooperation, parental care, predators  All provide a selective force that would drive selection for recognition mechanisms  Why live in groups? o Ultimate hypothesis - Why it benefits organism – fitness, reproductive success  Avoiding being eaten – able to improve defence  Foraging efficiency in groups is greater  Help with rearing offspring  All from vole lecture o Proximate hypotheses – how does one recognize predator or kin?  Does an animal learn recognition cues? Is there transmission of those cues and information  Maternal/ parental care  Reproductive physiology gives an honest signal  Olfactory cues individual can use  Nests of Polistes… o Can look at animals that live in solitary to eusocial communities o Polistes contain odours that allow recognition  When does a wasp learn odour of its nest?  Looking at it developmentally  Immediately after eclosion from pupal case, a wasp is a very young adult wasp. Isolating  find no tolerance of nest mates (have not learned odour of nest). Given an hour of contact with nest mates, are better able to withstand nest mates. After an hour, they learn the odour  Like the critical period for learning in ducks (imprinting). There is a developmental period that the organism is most sensitive to learning odour cue  Kin discrimination o Why learn? Learning only odour of nest mates or of self? o Article: squirrel kin recognition  Squirrel live in family groups. Men disperse further than women. After hibernation, can still recognize kin o Rearing groups for newborn  Animals reared together had less aggressive encounters  Rearing animals together – learn odour of their family group  Kin discrimination o Siblings reared apart  Lowest amount of aggressive encounters were in pairs that were female- female  Male-female pairs (siblings or not) show more aggressive encounters. Particularly sibling pairs  How to be recognized? “armpit effect” o Learning odour of self – learn to recognize people with similar odours o If going into an elevator and someone is wearing lots of perfume  Habituation ends up happening o Cube is presented with an odour and is shown in 3 trials. Over time there is less investigative sniffing of the cube o Habituation happens over time o Increased relatedness to mother than to non-kin  How much sniffing happens for the mom?  A lot less  sniffing as if it is habituated to the mother o Non-kin sniffing is much increased o Squirrel knows its own odour and compares to non-kin  Why might kin recognition be adaptive? o Adaptive: (define) o Kin recognition: (define) o Are adaptive if you can recognize your kin o Altruistic interaction – genes are passed on if kin help each other o Predator avoidance o Mate recognition  Ant communication o Use this information in terms of communication o Expect that there is aggression, investigation, assault and dismemberment o How do ants investigate an intruder into the nest?  Ants use: pheromones,  Look at the tarsi  If investigating ant from same or different colony, see contact with the legs  Ants become very aggressive with intruders  Sting the intruding ant and dismember it o Also produce a pheromone that produces a response in other members of their colony (alarm pheromones)  Ant olfactory compounds for recognition o Might be using compound recognition to recognize intruders in the nest  Not just intruders they are recognizing. Might be recognizing nest mates  Why do they need to recognize nest mates?  For aggression, shared food sources, mating, queen ant  might release a compound that suppresses ants from mating based on info we know from bees  Worker ants care for queen’s eggs and larvae – they do NOT reproduce  Social hierarchy – queen gets all the action, workers could be disgruntled  (website) o Antennating the foreign intruder  Ant olfactory compounds for recognition o A foreign worker has a high number of aggressive attacks done to it o When ants are treated with hexane, there is low aggression if the ant is of the same colony o 2 other compounds that:  Pentacosane  Causes aggression  Nonacosane  Low amounts of aggression o Antennal inspections – inspect foreign worker for antennae  Significantly higher with pentacosane o Sometimes workers can sneak reproductions – when this happens, their cuticle betrays their cheater status  Ant olfactory compounds for recognition o Queen cuticle has specific carbon chain length as peaks. Workers have a different profile o Reproductive worker cuticle is similar to queen cuticle – some peaks match the other o Non-reproductive cuticle – not like the queen cuticle or reproductive worker cuticle o Queen does most of the reproduction o Workers that are cheaters have compounds that match the queens  Cuticles are much different from non-reproductive cuticle o Noticed that there were some that increased aggression – same response that the ants have to a reproductive worker o If a worker ant begins reproduction, other ants increase the aggressive attacks and antennate, assault and dismember cheaters o Paint a non-reproductive worker with pentacosane and reintroduce into nest, see increased antennal impressions o Nonacosane does NOT elicit same response o Something about physiology causes this to happen – honest signals of reproduction.  Signals that other ants can recognize  Colony recognition in Fire Ants o Ants typically do not accept more than one queen  If there is another queen, only one reproductive is tolerated  Some ants tolerate more than one reproductive ant o Monogynous – only tolerate one queen o Polygynous – more than one queen  Colony social organization o Can say there is a monogyne and polygyne colony o Researchers: grind ants and run on protein gel  Differences on certain protein  Differed with mono and polygyne o What was the type of protein causing different behaviours? o Monogyne had one type of band  BB genotype workers o Polygyne had many types of bands  BB and Bb workers  Aggression towards a queen o How do ants recognized one queen from another o Isolated queens from polygyne colonies  Later looked at level of aggression  Then grinded them out and looked at proteins  How do ants recognize the queen’s genotype? o Prediction: ants acquire an odour to sense an odour from the queen o Queen that they attacked (BB)  40% were killed o If queens were polygynous were not killed  Ants respond with aggression if the queen is a particular genotype o When queen was BB, most workers attacking were Bb (heterozygous)  Ants respond with aggression if queen was particular genotype  Polygyne colonies: o Perhaps ant recognized scent of queen o Haplotype of polygyne colonies:  Bb x B  BB  Bb  Bb x b  bB  bb - often die – only in polygyne colonies  gp-9 the “green beard gene” o presence of small b allele allows the ants to recognize the queen and identify queen  “Green Beard effect” o If ant was having a green beard, they would be identifiable o Presence of genotype enables ants to recognize queen and respond to that genotype o Identity of gp-9?  Went from protein to DNA to identify the particular gene o Gene giving gp-9 not only confers a difference in acceptance versus one type of queen but also confers a difference in dispersal  Disperse further than BB o Queen phenotype is different from homozygous  Attacked queens have high fat reserves – can produce eggs faster o Polygynous colony has low fat reserves – slowly produce eggs  Colony recognition in fire ants o Fragments had different types of amino acids at 139, 136 o Sequencing gene in gp-9 found that it is an odorant binding protein  Important for bringing molecule closer to olfactory receptors  MHC and mating in Salmon o Ability to detect genotype of an organism perhaps by odour and that allows an organism to recognize its kin  Sensory cue used to detect genotype of organism o Looked at Major Histocompatibility Complex  Peptide sequences allow to find more foreign particles  Increase immune function o Female salmon mate non-randomly  When diverse, if are mating randomly see a certain pattern  For females, observed that they choose fish at the observed line o If mating with salmon with diverse MHC, can produce offspring that detect a wide arrange and produce more offspring  selects for non-random mating  MHC and social recognition o Bruce effect = pregnancy failure in mice exposed to urine of males with different haplotypes o H-2d o In 1 and 2, have balb x balb mice  When exposed to urine from other balb males, there is little pregnancy failure  When exposed to c57b6 – significantly higher amount of pregnancy failure  H2B + H2B exposed to balb urine – more pregnancy failure o What is it in urine that mice are detecting? Female mice are detecting something that causes pregnancy failure  Found isolated peptides from balb and c57  crossed balb x balb and added balb urine and added peptides of H2B genotype  Balb x balb + balb urine (with B peptides) – have as much pregnancy failure as if exposed to C58B6 urine  Mice are detecting PEPTIDES o What ultimate reason is there for pregnancy failure?  mice have increased pregnancy failure when encountering another genotype’s peptides  Cue in urine gives some information of if offspring will be viable  Information about what?  Could be that when they find a male very different from the one they mated with, selective pregnancy failure brings on estrous (“in heat”) in mice  Mice with pregnancy failure will go into estrous immediately  Inbreeding depression o = Inbred organisms have lower fitness of non-inbred members of their species o Avoiding inbreeding depression would increase the fitness of the organism – produce higher number of offspring themselves o With increased pregnancy failure, come into estrous to urine that is different from theirs o Urine similar to theirs are more likely to be related – when urine is different, are more likely to be unrelated  Why have more pregnancy failure when exposed to urine that is different?  To avoid inbreeding depression, a mouse that ma
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