Background The C Fern experiment revealed that while the M strain of Ceratopteris richardii can receive the signal to create dwarf males, it cannot produce it. The experiment also showed how a higher density of gametophytes would result in a higher percentage of dwarf males which would lead to greater genetic diversity. The next step in this study would be to determine whether or not the C Fern will produce more dwarf males if it is growing in adverse conditions in which case a greater genetic diversity would likely mean greater biological success. Hypothesis
The hypothesis is that although greater genetic diversity would be beneficial to a C fern community growing in adverse conditions, in actuality poor conditions will result in a lower percentage of dwarf males than there will be in normal conditions. Experimental Design The experiment will be conducted using only the W strain which both produces and receives the dwarf male signal. The concentration of W filtrate used will be 1:1 for every trial to keep it constant. The plates of this strain and concentration will be prepared with a single pH buffer: one of each pH from 1 to 14.
There will be a total of 42 plates so as to have 3 trials of each pH. The plates will be left to grow inside at the same temperature and light intensity for 20 days at which time the percent of dwarf males will be calculated and compared. Expected Results I believe that dwarf male production will be highest at about pH 6 and lowest at pH 14. This is because the greater percentage of dwarf males in dense populations of C fern gametophytes in the original experiment was due to a greater number of chemical signals coming in contact with a greater number of spores.
If the gametophytes do not become more dense, there will be no way for the signal to reach more spores; the C fern will not react to poor conditions by creating more signal than that of a fern growing in normal conditions. It is likely that because the spores are being grown in adverse conditions that there will actually be a lower percentage of dwarf males because they will grow in a smaller density. Past studies have shown that the optimal pH for C. ichardii is near pH 6 and that its production declines at any pH above 8 (Wright, Hickock, and Warne, 1990). For this reason, both the density of the gametophytes and the percent of dwarf males will be highest at pH 6 and lowest at the subpar conditions above pH 8. Work Cited Wright, S. R. , Hickock, L. G. , and Warne, T. R. (1990). Characterization of mutants of ceratopteris richardii selected on aluminum (al2(so4)3-na2edta) . Plant Science, 68(2), 257-262 .