BIOL 180 Lecture Notes - Lecture 47: Coevolution, Parasitism, Keystone Species
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Lecture topic: mutualisms, coevolution, and community structure & dynamics. In facilitation, only one species in an interaction benefits, while the other one suffers and sees a decrease in fitness. In mutualism, both species in an interaction benefit from the relationship. Think of mutualisms as trades both participants benefit: something will always be transferred, for ex. Think of a fungus wrapped on a plant"s roots (the plant-mycorrhizae association) Mutualisms occurs between nitrogen-fixing bacteria and the plant species that house them in their tissues: the host plants provide sugars and protection to the bacteria; the bacteria supply ammonia or nitrate in return. Mutualism is also common between bacteria and animals, particularly in the digestive systems of the hosts: host gives a habitat of the bacteria; the bacteria gives digestive favors to the host. Multiple consumption interactions can be linked sequentially into a food chain: overlapping food chains lead to food webs.
