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Ecology Assignment

Submitted by jgcahoon on Fri, 11/17/2017 - 10:12

Part A

            I do not expect to observe the relationship between regional and local species richness in nature because the slope of the line is greater than 1, which is virtually impossible to achieve in nature. The slope of this line is greater than one because there are a greater amount of local species richness than regional species richness. This is impossible in nature because the spatial area of a region is larger than that of a local area.

Part B

            Based on this study, I believe that regional processes are the dominant driver of this pattern displayed in the graph. My first reason for this is the fact that the slope is slightly below 1, but does not level off (i.e. plateau) as regional species richness increases. Also, the local richness values are lower than regional richness values, but still increase with them proportionally in Study area 1, which is common of a regional process being the dominant driver in an area.

Part C

            Based on the equilibrium theory of island biogeography, I believe that the regional species richness on the mainland will affect how many species are predicted to be found on other islands. This theory talks about how immigration and extinction can affect the number of species on the smaller islands scattered around the mainland. Over time, an equilibrium is said to be made between these two rates, which will affect how many species are on other islands. 

Plant Ecology

Submitted by jgcahoon on Wed, 11/15/2017 - 22:51

There are many competitive advantages of early emergence. The first is how plants that emerge early get first access to the resources in that area. M. A. Ross and John Harper (1972) showed this in their experiment, and came to the conclusion that plants that appeared above the ground first were 1000 times larger than those who appeared last, most likely due to the disproportionate amount of resources between the two. Plants that emerge early will also be able to mature faster than plants that emerge at a later time, and therefore can possibly pick the best locations for resources first. 

Localized vs Systemic Defense

Submitted by jgcahoon on Wed, 11/08/2017 - 17:15

A localized defense response could be more beneficial than a systemic response depending on the type of injury/danger that is present. If there is a lot of damage done on a plant, a systemic response might be useless due to too much tissue loss. At this point, the damages would be too much for the plan to handle, and there might be no use in saving it. Also, if there was a lot of damage done to the plant, this may hinder the signaling ability of the plant, which would affect the systemic response. Localized defense responses would be better for smaller injuries, or injuries that are located in one specific area, rather than most of the plant. Localized responses may use tissues that are quicker at repairing the damages done to the plant, while systemic responses may take longer to heal due to the severity of the situation. 

Generalist vs Specialist

Submitted by jgcahoon on Wed, 11/08/2017 - 17:14

Graph A (generalist) supports the hypothesis that plants can respond to herbivory by reducing their edibility to herbivores. One difference between the two graphs is how when the defenses of the pepperweed plant were induced, the percentage of leaf consumed in both the choice and no choice categories were significantly less in the generalist group than the specialist group. Another key difference was that the generalist caterpillars did more damage to the plants whose defenses hadn’t been induced, while the specialist caterpillars produced roughly the same amount of damage in both the control and induced plants.. I think these differences may be because specialists usually only focus on a small set of species that they consume, so they would be better suited to consume plants that they are specialized to, since they are accustomed to that plants’ defense. 

Plant Ecology Practice Exam

Submitted by jgcahoon on Tue, 11/07/2017 - 16:18

Primary succession happens when plants colonize ground that has previously not been colonized by plants before. In primary succession, soil is formed, which helps the plant community develop. Secondary succession occurs when plants colonize land that had already been colonized before. Soil already exists here, and regrowth after an intense fire is an example of secondary succession. I believe primary succession will be slower, because plants would have to colonize land that’s brand new to them. Soil will have to form which may take a while, and other components would have to be present in the soil to start the growth of plants. In primary succession, the plants have to rely on a new foundation, but in secondary succession, the foundation had already been made. 

Abstract for Proposal

Submitted by jgcahoon on Thu, 11/02/2017 - 14:42

The ability to respond to various stimuli in an organism’s environment is important for survival. In order to produce a response to the various external stimuli, an organism must use its central nervous system to respond. The planarian is an easy organism to test its central nervous system and learning abilities because it is relatively easy to manipulate and see a response. Planarians are photophobic ,meaning they are sensitive to light. By using a light stimulus, we can view the planarians response to see how they react. In this experiment, an apparatus with a light bulb underneath and a battery will be used to test the planarians conditioning response to two stimuli (light and a shock). The light stimulus will be paired with the shock in one group, while the other group will be a random combination of light and shock. This experiment will be testing whether the planarian was able to condition itself to the shock stimulus, whether it was paired with the light or not.


Submitted by jgcahoon on Thu, 11/02/2017 - 14:41

The results of this experiment will show if planarians can be conditioned by a light/shock stimulus. If they are able to, then they’re similar to other organisms that can respond to stimuli from the environment. Various other researchers have noticed that planarians have similar nervous systems as vertebrates, both anatomically and chemically. If the planarians used in this experiment are able to condition themselves to their environment, this further supports researcher’s beliefs that planarians and vertebrates are similar in nervous system structure.

Writing for Persuasion Activity

Submitted by jgcahoon on Wed, 11/01/2017 - 19:23

If a new retrovirus were to kill all domestic dogs and we could only save one breed, I would save the Siberian Husky. First, their beautiful blue eyes light up a room, and their fur is very fun to massage your hands through. Their fur is double coated, due to the fact that this breed started out pulling sleds in Russia. They are also more intelligent than other dog breeds, and can live to an average age of 14. They’re considered a medium-sized dog, which is important to someone like me who isn’t a fan of larger dogs.

One of the more annoying things I find about dogs is how some breeds bark continuously. The Siberian husky rarely barks, if at all, and tends to be a more relaxed breed. Also, Siberian huskies only shed their fur depending on where they are living. In a climate like the one here in Massachusetts, this breed would only shed their fur in the summer time. People tend to dislike dogs because of their gross behavior, but Siberian huskies are a rather clean breed. They have very little drool, and they don’t shed too much (depending where you live). The Siberian husky will love you unconditionally since this breed loves human company, and will do whatever you want with you, including going on jogs or walks through the woods.

Literature Review cont. Pt. 2

Submitted by jgcahoon on Tue, 10/31/2017 - 21:18

Planarian may seem like basic organisms, but their importance to the science community for their relatively easy use in experiments makes them much more than average. The ability to manipulate them with various stimuli (i.e. light, electric shock, danger, etc.) helps us learn more about its simple nervous system. In an experiment by   Wisenden and Millard (2001), fish odor and a neutral stimulus caused little reaction from a planarian, but when this odor was paired with injury-released chemicals from the planarian, the planarian began to avoid the fish odor. This smell was now associated with risk and danger, which some believe is due to their simple nervous system.

Literature Review cont.

Submitted by jgcahoon on Mon, 10/30/2017 - 19:26

Baxter and Kimmel (1963) helped further by looking at the conditioned response over time that were either paired or unpaired with a light and shock stimulus. The paired group received the light for three seconds with the shock being used during the last second. The unpaired group received one of the stimuli at random, and then the other stimulus not choses was presented after 15 seconds. After five blocks of 50 conditioning trials, the number of conditioned responses was twice as large in the paired group when compared to the unpaired one. This demonstrates the learning ability of the planarians in the paired group. One flaw of this experiment was how it took place in a dimly lit room. This could generate some, “background,” light, and therefore slightly affect the conditioned responses, due to the photophobic behavior of the planarians.


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