On feeding on more than one trophic level.
Dotted lines indicate estimated trophic levels, assuming a trophic level fractionation of 3.4 units.
An additional trophic level might include birds, which prey on snakes, but these were not sampled in this study.
However, an additional trophic level may exist which includes medium-sized mammals preying on snakes.
However, these studies did not measure the effects of nitrogen on the third trophic level, the parasitoid.
The distribution of spiders may be less affected by the distribution of plant species, because they are one trophic level further away from the defence chemicals of plants.
This is crucial because the effects of these resistance factors are also likely to be manifested in the third trophic level, that is, on natural enemies.
The aim of the present study is to quantify levels of diversification of an endemic snail fauna that represents one of the major components of the metazoan consumer trophic level.
