User:Madeleine Naish/Notebook/Biology 210 at AU

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.

MN

1-21-15 I have successfully entered a post! MN