User:Madeleine Naish/Notebook/Biology 210 at AU

January 21, 2015: Algae and Protists in Hay Infusion Culture

I. Purpose

In this experiment, different organisms from different areas of a hay infusion culture are observed. The purpose of these observations are to allow for a better understanding of the degree of biodiversity that can be found in ecosystems—even very small ones. The hypothesis for this experiment is that organisms from two different niches of the culture—the surface and the bottom of the jar—will themselves be very different. A prediction for this experiment is that the organisms at the bottom of the jar will be smaller.

II. Materials and Methods

The soil and plant life of the marsh transect of American University was sampled from and placed into a sterile 50 mL conical tube. 10-12 grams of the sample was placed in a plastic jar, along with 500 mLs of deerpark water and 0.1 gm dried milk. The contents of the jar were mixed gently, and then the jar’s lid was removed. The jar remained in the lab in this state for a week. After a week, two slides were made of two samples from the transect. One sample was drawn from the surface of the water, while the other was drawn from the dark dirt at the bottom of the jar. Both samples were drawn out with plastic pipettes and placed on slides and covered with coverslips. Three different organisms were identified from each wet mount with the use of a microscope and dichotomous key.

III. Data and Observations

After a week in the jar, the hay infusion culture had a very strong, swampy smell. A white, mold-like substance had grown at the surface, and brown dirt and other substances had accumulated at the bottom of the jar.

Hay Infusion Culture

From the sample taken from the surface of the water, three different organisms were observed:

Paramecium multimicronucleaum, a motile cell at 100 µm;

Blepharisma sp., a non-motile cell at 450 µm;

and Pandorina, a colony with seven large cells and many more small ones, measuring at 70 µm.

From the sample taken from the bottom of the jar, three other different organisms were observed: Paramecium bursaria, a small, dark, motile cell measuring at 50-60 µm;

Amoeba proteus, a motile, dotted cell measuring at 20 µm;

and Copidium sp., a cilia-covered cell measuring at 60 µm.

IV. Conclusions and Future Directions This experiment revealed that a great amount of biodiversity can exist in very small ecosystems. The six organisms found in the hay infusion culture never repeated. Though the hypothesis was proved correct for this experiment, because the organisms found at the top were different from those found at the bottom, this finding did not reveal much about the variation of niches within an ecosystem because it was not specific enough, and because the organisms within the same niches were ‘different.’ Different was not sufficiently defined, which is a necessity and something that would improve any future trials of this experiment. However, the prediction that the organisms at the bottom would be smaller than those at the top was proved correct, and this is slightly more insightful. All the organisms from the bottom of the jar measured to be 20-60 µm, while those from the top grew much bigger at 70-450 µm. One reason the organisms at the surface of the culture may have differed from those at the bottom is their differing proximity to the plant matter in the jar. Though the plant matter was generally quite mixed up in the culture, a lot of it was floating at the surface, meaning the organisms from the top would have been closer to the plant life than those at the bottom. Proximity to plant matter can change those organisms nearby because plant matter will eventually decompose, and nearby organisms can get nutrition from this process. This would be how an organism from the top niche would probably meet one of the needs of life: energy. Pandorina is an example from the top. Because this organism lives in a colony it is composed of several cells that can transmit information to each other and continue replicating to increase their number. They most likely show signs of evolution simply by being in colonies, which is complex. After two months of living in this ecosystem, however, these complex organisms might not be faring so well. So much of the existing plant matter would have decomposed, and so much of the available oxygen would have been used up without proper replacement. This would make it difficult for Pandorina, and the other organisms, to survive.

MN

January 14, 2015: Evolution observed in the Volvocine Line

I. Purpose

In order to better understand the effects of evolution over time, three different organisms from the Volvocine Line will be observed in this experiment. These members of the Volvocine Line are known to have evolved from each other, and therefore their differences and similarities can give new insight on how evolution leads to genotypic and phenotypic change. The hypothesis for this experiment is that, the more recent a member of the Volvocine Line is that is being studied, the more complex it will be. If this is true, then the more complex organisms will be found in increasingly larger colonies.

II. Materials and Methods

Slides were made for the three organisms. This required samples, taken with the use of plastic pipettes, from Chlamydomonas, Gonium and Volvox, which were placed onto slides and then covered with coverslips. Before being covered with a coverslip, a drop of protoslo was placed on Chlamydomonas for easier viewing. All three organisms were viewed under a microscope, to allow their cell number, colony size, mechanisms of motility and method of sexual reproduction to be observed.

III. Data and Obseravations

The results of the study of the members of the Volvocine Line can be seen in Table 1.

Drawings of the view of the organisms through the microscope can be seen below.

Chlamydomonas Gonium Volvox

IV. Conclusions and Future Directions

The experiment revealed the more recent organisms were more complex than the older organisms. This complexity has to do with several things. First, it has to do with whether or not the cells formed a colony. Chlamydomonas, the oldest organism, does not live in colonies, whereas Gonium and Volvox were found to live in colonies. Volvox, the youngest organism, lived in the largest colony, with hundreds of cells in each. Complexity also has to do with how the cells sexually reproduced—either through isogamy or oogamy, the latter being the more complex method. Chlamydomonas, the oldest organism, once more displayed the least complexity by reproducing through isogamy, while the other two organisms reproduced through oogamy. The results of the experiment show that the process of evolution can lead to more complexity, proving the hypothesis correct. This complexity was indeed displayed through the quality of colonies, among other things. This experiment provided a good understanding of the kind of changes evolution can lead to. However, because increased complexity is not always the result of evolution, a future experiment might observe organisms that did not grow more complex through evolution.

Niches at AU

The niche I observed was the marsh at American University. This niche is located across the street from the Katzen Arts Center, at the base of a slightly sloped hill, with part of its perimeter next to pavement. The other part is surrounded by grass, though this grass ends not too far off, with the pavement along the street. There is a manhole in the rock area, but it is otherwise a very natural niche with several types of plants. Some abiotic factors within the transect are light, coming from the sky above, water, coming from the snow melting on the ground, rock, dirt, which is the bottom layer of the transect, and the manhole. Some biotic factors are moss on the ground, grass on the ground, clovers growing in the eastern area, the butterfly bush growing in the southeastern corner, and cattails growing near the center of the transect.

File:Transect.png Transect

MN

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