Data from: Realized trophic niche driven by apparent competition: an example with marsupials

According to apparent competition theory, the co-occurrence of
two species that share the same predators appear to affect each other’s
population growth and abundance. However, as a result of habitat loss and
over-hunting, top predators are being made rare worldwide. Taking into
account that apparent competitors share similar resources, we would expect
the absence of top predators to reflect in changes on prey realized trophic
niches. To test our hypothesis, we developed a model to predict the
abundance ratio of apparent competitor species based on changes in their
realized trophic niches. We tested our model against field data on the
Neotropical marsupials Didelphis aurita and Metachirus nudicaudatus. Our
results revealed that D. aurita and M. nudicaudatus are two species under
apparent competition and their realized trophic niche and diet overlap
change according to the presence of top predators. The model was able to
predict the actual relative abundances of D. aurita and M. nudicaudatus in
the three empirical studies analyzed. Our study presents quantitative
support to the apparent competition theory; however, the model’s
applications to other groups still need to be verified. Additionally, our
study shows that the lack of top predators has consequences on the realized
trophic niche of their prey and, therefore, we reinforce that conservation
plans need to focus on the effects of top predator loss on ecosystems.