Keystone species can be identified based on motif centrality

Species extinctions can lead to the collapse of our ecosystems. So, biodiversity conservation is significant in protecting our environment. Identifying the roles of species on ecological network robustness is an effective way to conserve biodiversity. Previous studies have mostly focused on the role of an individual species in the whole food web. They ignored the truth that food webs consist of a large number of motifs (patterns of interconnections occurring in complex networks at numbers that are significantly higher than those in randomized networks). Here, we proposed motif-based centrality measurements to identify keystone species. Both topological and dynamical approaches were employed to assess changes in ecosystem stability. After removing species according to various deletion sequences based on different motif centralities, secondary extinctions were recorded during sequential removals, and then robustness was calculated. We found that species with higher motif-based centrality (those who participated more food-web motifs) were more influential. It indicates that the motif-based centrality is an effective indicator for the identification of keystone species. Our findings emphasized the importance of motifs when detecting the role of a species in maintaining local biodiversity and provided a new aspect of environment management.