  Ecological networks exhibit non-random structural patterns, such as
modularity and nestedness, which indicate ecosystem stability, species
diversity, and connectance. Such structure-stability relationships are well
known. However, another important perspective is less well understood: the
relationship between the environment and structure. Inspired by theoretical
studies that suggest that network structure can change due to environmental
variability, we collected data on a number of empirical food webs and
mutualistic networks and evaluated the effect of climatic seasonality on
ecological network structure. As expected, we found that climatic seasonality
affects ecological network structure. In particular, an increase in modularity
due to climatic seasonality was observed in food webs; however, it is debatable
whether this occurs in mutualistic networks. Interestingly, the type of
climatic seasonality that affects network structure differs with ecosystem
type. Rainfall and temperature seasonality influence freshwater food webs and
mutualistic networks, respectively; food webs are smaller, and more modular,
with increasing rainfall seasonality. Mutualistic networks exhibit a higher
diversity (particularly of animals) with increasing temperature seasonality.
These results confirm the theoretical prediction that stability increases with
greater perturbation. Although these results are still debatable because of
several limitations in the data analysis, they may enhance our understanding of
environment-structure relationships.
