On pages 77-83 Dr. Moalem discusses how plants have natural defenses that form to benefit the plants in certain ways. Dr. Moalem shows how some plants have phytoestrogens to reduce the number of predators in the next generation by causing problems to their reproductive process. Some plants have chemicals that cause paralysis and some plants have chemicals that effect only mammals, but not birds which helps seed spreading and allows for more population growth. This relates to big idea #1 in which the process of evolution drives the diversity and unity of life. Plants use their chemical defenses to survive more effectively, but also to spread reproduction to a higher rate and to a farther radius.
Dr. Moalem states that there are many plants that have such chemical defenses. Find and research a specific plant that has natural chemical defenses against predators. Find out what the chemical defense does to the predator and how that defense allows the plant to survive and reproduce more successfully. When describing what a chemical defense does to a predator, use specific details on what the defense does to harm a biological function to the predator. Is there a specific reason why the defense effects that certain biological function?
(Sam Lee salee4@students.d125.org)
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ReplyDeleteOne plant that uses a chemical defense against predators is the Strychnine Tree. The odorless, white chemical that the tree secretes is called Strychnine, which is a very powerful neurotransmitter inhibitor. The Examiner discusses in the article titled “Strychnine poisoning used as population control for Iraqi street dogs” states that strychnine causes paralysis in dogs that eat meat infused with strychnine. The affected dog eventually has his/her respiratory muscles relax, causing respiratory failure and death by asphyxiation.
ReplyDeleteThe Strychnine tree has a selective advantage over other plants because most animals will only be able to eat the tree once before dying. Dr. Moalem states that “plant have…all those committed vegetarians grazing and buzzing and flying around that rely solely on them for food,” (80) and strychnine can help eliminate these predators. This explains why strychnine makes a good pesticide, or rat poison. Even if the predator somehow survives ingesting strychnine, it may have brain damage from a stroke that strychnine can cause, and will likely never eat that plant again, or any plant that looks similar. This causes the plants with strychnine to be selected for by the environment, because a very large environmental pressure is predation, and if all of the predators die or avoid the plant after eating it, it will increases the plant's overall fitness. This relates to Big Idea #1 because trees was being eaten by rats and insects, and over time directional selection moved towards the trees with higher doses of strychnine, which created a new species, the Strychnine tree.
I would say that strychnine is affecting the muscles for a specific reason. Without the use of its muscles, a predator of the Strychnine tree would not be able to chew any more of the tree's leaves/bark. Also, paralysis of the predators leads to respiratory failure, which almost ensures the predator will die if Strychnine is consumed in a large dose.
Mahaney, Patrick. "Strychnine Poisoning Used as Population Control for Iraqi Street Canines." Examiner 17 Feb. 2009: n. pag. Print.
(Zachary Rane zrane3@students.d125.org)