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Lecture 12

BIOL 103 Lecture 12: Biology Week 12

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BIOL 103
Virginia K Walker

Biology Week 12 Field of canola o Monoculture makes it susceptible to pathogens o Genetically modified canola Monsanto Bananas o The seeds are not noticible but these bananas are modified o Cavendish Bananas Isolated from a mutated triploid, sterile plant o Isolated and grown and cultivated o La Gros Michael was the most popular banana in the world wiped out by the panama disease be fusarium o Peppers get infected and killed by insects with the disease fusarium o Cavendish has been under attack from panama disease in the last 10 years o Cavendish must be sprayed with insecitcies in order to be protected throughout their growth Pink Lady Apples o Must be human made or cultivated from mutant trees Protecting biodiversity o Monsanto wants to grow plants that are engineered to resist all types of insecticides o Built a system where weeds could be eliminated and only the desired plants would flourish o Monsanto owns both the insecticide Roundup and the Roundup Ready Plants that are resistant to their own insecticide o Sells these seeds to farmers who can no longer cultivate a normal crop o Roundup 2 glyphocate blocks a pathway to again make a plant resistant to insecticide o Health concerns of glyphocate Could be carcinogenetic Scandal involving the rumor that Monsanto paid scientists to ghost write papers for other scientists that are not affiliated with the company saying that nothing they do is harmful Food chains o Trophic structure defines the feeding relationships between organisms in a community o Food chains describe the passage of energy from primary producers to consumers and then back to decomposers o Food chains are limited in length because 1. Energetic inefficiency of transfer through links 2. Instability increasing through increasing trophic levels o Plants photosynthesize energy so that primary consumers such as a herbivore can obtain energy Why are food chains so short? o The energetic hypothesis suggests that short food chains are the result of inefficient energy transfer between trophic levels o Inefficiency of energy transfer o Little energy is transferred by the consumption of another organism o 8090 of the energy created by the producerprimary consumer is lost once it gets to the final consumer o Energy is lost to heat o Energy is disapated very quickly o The dynamic instability hypothesis suggests that long chains are inherently vulnerable to perturbation o When you have long food chains the next step depends on the previous step o If there is a traumatic event to a population, it affects the next links in the food chain directly Food webs Dominant species o Some species dominate communities, suggesting they are competitively superior in that environment o The American chestnut wiped out by disease o Was important to a few species but was overall replacable o Invasive species may become dominant because in their new range there are no specialist parasites or predators to keep them in check o Invasive species come into new habitats and dont really have any enemies o Zebra mussels come over on ships from other countries spread into lakes and clear up the water but are also invasive and take out organic matter o They displace other species of aquatic life o Round gobies another invasive speciesthey are both predators and prey and can cause the displacement of common species in the area Keystone species o Exert control on community structure: SEA OTTERS Exert control over the sea urchin population
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