19+20 infection and behaviour Flashcards
Main topics 6
1) Mate attractiveness
2) Indirect gene benefits and models
3) Sickness behaviour responses
4) Parasitic manipulation of behaviour of transmission
5) Malaria
6) Fungus and zombie ants
Mate attractiveness signals relates to immunity 3
Visual
Acoustic
Chemical (sexy signals)
Visual signals and immunity 2
Banded danselfly- darker wing spots mean lower load
House finch - dull plumage means parasitic mites and pox lesions
Acoustic sign of immunity
Wolf spiders
High drumming means high encapsulation which means high immune function
Chemical sign of immunity sexy signals
Beetles
Females prefer pheromones from males that indicate
a)high encapsulation rate
B) phenol oxidase response to immune insult
Why this association between smell for encapsulation and phenol oxidase response with being sexy?
M can maintain signal despite immune deficiency or this is a signal for immunity
So
Less likely to be carrying infection- which could directly affect f
Like to carry genes that will increase odd Spring fitness or confer resistance
What are the two hypotheses for indirect gene benefit
Good genes
Parasite mediated model of sexual selection
Good genes hypothesis
That broad threat from parasites / pathogens mean genes affecting immunity are good candidates for “good genes” so m will inherit chargerr females are selecting for and females will inherit preference for them
Problem - if the chosen mate then gave considerable offspring fitness advantage then genetic variation would be difficult to maintain??
Parasite mediated model of sexual selection
Hamilton and zuk
Explains gen variation
When parasite 1 common m1 preference spreads then when areas it’s 2 common this preference spreads
Sexual displays are reliable indicators of gen resistance and resistance is genetic
How do females distinguish sexy males that are immune 4
1) bright plumage and fur
2) bare patches of skin to assess blood
3) contests and fights
4) exhausting athletic displays
How to test sexual selection parasite hypothesis
Need to know parasite load in hosts
Need to know phenotypic markets used in female choice
If hypothesis is true those with most evident sexual selection will be most subjected to depilating parasites
Sexual selection parasite model example of spp
Female sticklebacks
Use make coloration in mate choice
Prefer bright red spots
When used green light couldn’t see red and this red preference was lost
When males infected with fungus have white spot and dull
Therefore redness of father predicts offspring resistance to infect
Infection causing sickness and am adaptive response by the host - intro - can cause 5
Behaviour change could be adaptive response ie
Increase sws
Decrease activity
Decrease appetite
Physiological changes he deplete plasma iron
Thermoregukagir set point
Main two things for infection and animal behaviour
Anorexia
Self medication
Anorexia 3 animals
Hedgehogs - foot and mouth disease
Mice - if forced to eat higher mortality and survivors if allowed to choose had lower body weight
Crickets -when infected with bacteria less feeding and immune crickets chose low fat is head and avoided high fat or abdomen thorax and legs
Molecular basis of anorexia response
How
Protein alipophorin 3
Lipid transport of protein cvs immune function competition leads to stress induced immunosuppression
Anorexia is thus to minimise this convo and boost disease resistance
Lipid transport molecular that results in trade off
apolipophorin 3
Self medication and example
Woolly bear caterpillars
Sickness behaviour as response to infection - adaptive plasticity caused increased consumption of PLANT TOXINS to increase survival (although usually is bad) in jests PYRROLIZIDINE ALKALOIDS PA
What to Woolley carter pillars start to ingest
PYRROLIZIDINE alkaloids
PA
Behaviour and infection parasitic manipulation 5
Direct Indirect Vector Malaria Fungus ants
Direct transmission
Increase dispersal or getting into host at times of day or cercariea at dif times of day
Indirect (3)
Trematodes- parasite in head of brain pulsing
Mice- toxoplasma Gondi - risk and cat wee
Crickets - hair worms jumping into water
Vector borne is p yoelli
Females in oocyst experience downregukatiom of behaviours
Host seeking
Persistence
Probing
To allow development
Then increase feeding and number of bites
Increase emortality once develops in midgut
Increase biting rate when f infectious
Malaria and mosquito manipulation 4 things
Infection means increased Persistence Probing Satiation threshold Alters ILP
ILP what is it and why relevant to mosquito
Insulin like peptides
Expression in midgut
Regulate sensitivity of odorants receptors and key in regulating blood meal and digestion
and reproduction
Benefits parasite as increase percentage of females that survive to bite at the correct time
This is not specific to malaria infection
Fungus and zombie ants
O unilateral
Secretes different chemicals in different ants GABA and sphinosine - normal ants rarely leave set foraging trails
Zombies ants leave them
At time of biting anthrax full of fungal cells - muscles that control opening / closing of mandible appear totally atrophied
Different chemicals in zombie ants
GBA
Sphinosine
At time of biting what happens in zombie ants
Head is full of fungal cells
Muscles that control opening / closing of mandible become fully atrophied
General :
How many parasites
What do they do to host
Pressure implicates evolution of 3
50% organisms are parasites
Costly to host Fast evolution as first gen times so implicates evolution of Immune response Sex Behaviour
