BIO 200 Lecture Notes - Lecture 19: Oatmeal, Ecotone, Snowshoe Hare
2 Nov 2017
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Document Summary
Parasites as selective agents: they harms the host and benefit from it: 1. 4 billion people carry nematode parasites, (ascaris) worms in their intestine. How do parasites affect the host: consume energy, destroy cells, obstruct functions of organs, produce toxins. Host can become extinct across entire range: e. g. chestnut blight fungus. In 1904 this fungus the squirrel population crashed and 5 moth species became extinct. If you are dependent on the host you can also become extinct. Co-existence of host & parasites: alternative hosts, e. g. african sleeping sickness. Infects humans & all hoofed animals (anteaters, pigs, horses, cows, buffalo) affects brain. You can be immune to the virus but there are other host possible. Identity switching to avoid immune system: e. g. influenza -high mutation rate, e. g. african sleeping sickness -parasite switches surface proteins so immune system can"t identify it. Co-evolution of parasite & host: e. g. myxoma virus & rabbits. Rabbits introduced into australia in 1859 to kill time by prison guards.
