Ecology Lecture 6
- Created by: emmawilliams
- Created on: 28-03-17 18:27
Parasite/host interactions
Parasites hard to define, sometimes considered a special case of predation.
One definition: ‘An organism which uses the metabolism of another organism to the detriment of its host without immediately killing it.
Some plant examples. e.g. Toothwort - woodland plant parasite of Hazel, Elm etc.
Broomrapes: 150 spp, tap in directly to host roots. (host legumes).
Indian-Pipe. Parasite of trees via their mycorrhizae fungi.
Mistletoe: semiparasitic (can photosynthesise).
Endoparasites (‘protozoa’ in blood)
Protists are examples of ‘microparasites’ - along with viruses, bacteria, some fungi etc.
Ectoparasite- Mite, Hippoboscid fly, Flea.
Evolutionary effects; microparasites are key to one important explanation for why sex exists.
Sex is a problem
-Maynard Smith’s idea
-Imagine a sexual population with N females and N males
-Each female produces K eggs
-Eggs have a survival probability S
=Thus in the next generation there will be KSN sexual individuals
Parthenogenetic mutant
-Females produce offspring without sex (a parthenogen)
-n parthenogenetic females
-Each produce K eggs with survival rate S
=Thus in the next generation there will be KSn parthenogenetic females
If the parthenogen is a mutant- then it will…
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