Bio2 Lecture 27

Bio2 Lecture 27 - Bio2 Lecture 27 Questions Which of the...

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Bio2 Lecture 27 4/28/05 Questions Which of the following is least likely to happen in an ecosystem? a) two species occupying the same niche reducing competition by character displacement most often involves a) directional selection a. involving 2 different species, and it increases the differences between them aggressive mimicry, like a spider mimicking a female moths pheromones difference between fundamental niche and realized niche is competition Coevolution - Reciprocally induced evolutionary change - Predation - Coevolutionary arms race - Red Queen Hypothesis o “In this place it takes all the running you can do, to keep in the same place.” o If your not evolving and changing you will become extinct, to keep in the same place is to keep from being extinct o Ltoka-Volterra Predator – Prey Model – visual representation of predator prey dependence Numbers of prey goes up, predator will soon follow, prey falls down, so will predators will also follow shortly - Symbiosis – always beneficial for at least one of the individuals in relationship o Mutualism – intimate long-term relationship advantageous for both partners Nitrogen fixing bacteria and legumes, bacteria invades the plant roots like peas or alfalfas, and used to be parasitic relationship, the bacteria, plant gives up some carbohydrates, and wraps the bacteria in a little ball on its roots, but they get nitrogen which is very important, nitrogen is required for photosynthesis nitrogen fixation, bacteria takes gaseous nitrogen and converts to ammonia Ant – acacia tree mutualism, big spines on the acacia tree give protection to big herbivores, but it gives no protection to little herbivores, such as leaf eating caterpillars, as well as parasitic vines, tree provides large spines, then ants hollow them out and live in them When you take the ants out, then the herbivores go up, vines go up, and acacia growth goes down
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Ants get a place to live, as well as food, at the base of the leaf are nectarines, and these nodules will exude sugars when tapped into o Commensalism – one species living on the other with no obvious effect on the second
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Bio2 Lecture 27 - Bio2 Lecture 27 Questions Which of the...

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