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The Pinnacle of Evolution

-us or parasites?
-parasites are a rival to humans in the part they play in evolution
-arms race between what's being parasitized and the parasites that is what drives evolution
-complicated interactions with prey


Evolutionary Arms Race

-between predator and prey
-where predation starts to slide into parasitism-really sophisticated way to use prey species
-parasites with complex life cycles and playing with mind of your prey
-cooperation between multiple pathogens and parasites to target single prey species


The Red Queen Hypothesis

-sex may be an adaptation to escape parasites
-mixing up of genes to keep them ahead



-over half of known animal species have parasite life styles in some or all of their life cycles
-one large class=parasitoids
-20% of all insects are parasitoids



-parasites in juvenile stage but free-living as adults


Braconid Wasps

-symbiotic relationship between parasitic wasp and polydnaviruses but pathogenic to host
-wasp doesn't only inject eggs but also virus particles so the caterpillar becomes an incubator and the eggs hatch and consume the insects innards but not its required organs that it needs to move around and function
-virus requires wasp to complete its life cycle in order to propagate its viral genome
-expression of virus genes inactivates caterpillars immune response to the wasp's eggs the eggs hatch then consume innards


Dirty Bacterial Tricks Activated Once Inside Insect

-bacteria switch from peacefully living in nematodes to producing insecticidal toxins
-bacteria make enzyme to digest insect
-bacteria make antibiotics to ward off bacterial competitors


Phorid Flies

-lay egg in thorax of ant
-larga eats innards of thorax
-when ready to pupate it crawls into head decapitating ant and adult fly hatches from head capsule


Types of Ants

-soldier, worker and minima
-minima ants ride on shoulders of worker ants and fend off phorid flies
-enough selective pressure on these flies that are parasitic of these ants that it calls for a class that acts as an extra step of protection


Mind Control Parasites

-don't just take over body and behavior but also get into minds of hosts


Birds and Nematodes and Ants

-nematodes live in bird poop, ant eats bird poop so now nematode in ant but birds don't eat enough ants so how do nematodes fix this?
-makes ants look like abdomen look like the berries that birds like to eat and stick them up in the air to attract the ant
-nematodes are tricky motherfuckers



-evolutonary advantage for the toxoplasma for mice to be eaten by cats so mice have to go near cats to be caught and eaten to transfer the parasite
-rats normally don't go near cats, instead venture toward bunny smell
-if rats are infected with this they go toward what smells like cats
-if humans have this you want to hang out with cats? or nothing at all you can just have it?
-modifies proteins in host brain and even gene expression in brain



-struggle against this disease involves evolution and society
-two hosts
-male and female gametes of parasite get sucked up into mosquito and unite
-make oocysts that releases stuff
-next time mosquito bites it transmits these cell to the human host which grows in the human body
-which eventually infects red blood cells where the gametes are produced again and then sucked up by mosquitoes in a vicious cycle
-plasmodium parasites carried from mosquito to human and back from human to mosquito


Natural Selection on Humans by a Parasite

-mutations in human populations that affect resistance to malaria
-sickle cell disease and other genetic diseases that affect blood cells can give resistance by blocking malaria parasite from reproducing in red blood cells
-mosquitos like the smell of people who are already infected


Malaria Experiment

-more attracted to scents of malaria-infected
children than non-infected.
-infected children, mosquitoes were more attracted to \
-children with gametocyte-stage Plasmodium (infective) than with other (non-infective) stages of the parasite.
-“strongly suggests that gametocytes increase the attractiveness of the children to mosquitoes”


Battling Malaria

-don’t target mosquito control to larvae or egg-laying young mosquitoes.
-develop “late-life-acting” insecticides that kill the older infectious mosquitoes -- note that these would be targeted at disease control, not insect control; you would still get mosquito bites, but not malaria.


Multicellular and Unicellular Dog

-single cell parasite arose few centuries ago within normal dog
-has own gene markers inherited from ancestor
-parasite passed from multicellular dog to multicellular dog where it forms a non lethal tumor
-tumor has ancestral genotype
-own genetic lineage and is obligate parasite
-distinct and novel form of dog
-passed as STD



-both species benefit
-gecko that pollinates flowers and gets protection in return