Australian house geckos are more aggressive than a globally successful invasive Asian house gecko

Invasive species are implicated in native species declines globally, but predicting the effect of specific invaders on a given native species remains difficult. Many successful invaders are highly aggressive, while others are not. The highly successful invasive Asian house gecko, Hemidactylus frenatus, has achieved a pan-tropical distribution. We investigated direct interactions between H. frenatus and a sympatric native Australian house gecko (Gehyra dubia) to determine the strength and nature of aggressive exclusion, and which species may be competitively superior. Intraspecific aggression was strong in the native, and individuals were more aggressive as residents than as intruders, suggesting this species shows site defence. In contrast, the invasive species displayed little aggression in intraspecific encounters. Overall, residents of the native species were more aggressive than residents of the invasive species. Aggression in the native species was influenced by the degree of aggre...