Question

When known numbers of seeds from two species (X and Y) are mixed together in different proportions and planted in five small plots of soil in the spring. The plants grow, flower, and produce seeds. It is found that the percentage of seeds of species X and species Y in the harvest is usually different from the proportion that was planted, although the total number of seeds produced is the same as the number of seeds planted. The data are plotted on the graph.

According to data what is the ecological relationship between species X and Y species?

• A. X and Y are mutualistic for low percentages of X seeds.
• B. X and Y are mutualistic for high percentages of X seeds.
• C. X and Y compete when both X and Y seeds are present.
• D. Y competes successfully against X at all percentages of X and Y seeds.
• E. X is a parasite of Y when Y is rare.

Answer 1

The correct option is C X and Y compete when both X and Y seeds are present.

Option C is the correct answer, X and Y compete when both X and Y seeds are present.

The graph shows that when the mixture of seeds planted contained 25% species X (and therefore 75% species Y, to make 100%), 50% of the seeds harvested were species X. If 50% of the seeds harvested were species X, the other 50% of the seeds harvested must have been species Y.