Competitive exclusion of a burying beetle by a mongoose

Abstract

Abstract Competitive exclusion, a mechanism for local extinction of organisms, has been well established among taxonomically related species, including those within the same genus, family, or class in animal communities. This study, however, focuses on competitive exclusion that occurs across phyla, exemplified by the exclusion of a native insect by an invading exotic mammal, where their food resources overlap. The hypothesis proposed in this study is that the small Indian mongoose (Herpestes auropunctatus) has caused the local extinction of a burying beetle (Nicrophorus nepalensis) on Okinawa Is., Japan due to competition for dead bodies of small vertebrates. To test this hypothesis, the beetles were collected from two areas - one where the mongoose has been controlled for over 10 years, including UNESCO’s natural World Heritage, and another where the mongoose has never been controlled or has/had been controlled for only a few years. The use of dead mice bodies laid on the forest floor was also observed in each area. The results showed that the beetle abundance was clearly higher in the former area than in the latter area, and no beetles were collected at sites far from the mongoose controlled area. The beetles often buried the dead mice for their reproduction in the former area, whereas in the latter area, the mongoose frequently fed on the dead mice. The beetle abundance in the former area significantly positively correlated with the canopy cover rate, while no such correlation was observed in the latter area due to the strong impact of the mongoose on the beetle abundance. These results provide the evidence of competitive exclusion of the burying beetle by the mongoose. This conclusion represents the world's first demonstration of competitive exclusion across phyla in the animal community.