Final answer:
T. agustifolia is limited by competition exploiting its realized niche. In the presence of T. latifolia, T. agustifolia occurs only in water > 20 cm deep.
Step-by-step explanation:
T. agustifolia is limited by competition exploiting its realized niche. The realized niche refers to the actual range of environmental conditions and resources that a species occupies in the presence of competitors or other ecological factors. In this case, T. agustifolia can live in water 0-20 cm deep by itself, but in the presence of T. latifolia, it occurs only in water > 20 cm deep. This suggests that the presence of T. latifolia is restricting the ecological niche of T. agustifolia to deeper waters.