1. Invasive species are a worldwide threat to biodiversity. Yet, our understanding of biological invasions remains incomplete, partly due to the difficulty of tracking and studying behavioral interactions in recently created species interactions.
2. We tested whether the interactions between the recently introduced invasive lizard Anolis cristatellus and the native Anolis oculatus in Dominica have led to changes in species recognition and aggressive behavior of the native species.
3. The use of realistic robots allowed us to test the behavioral response of 131 A. oculatus males towards relevant and controlled conspecific vs. heterospecific stimuli, directly in the field and in two contexts (allopatry vs. sympatry).
4. Our results show that species recognition evolved prior to sympatry in A. oculatus. Moreover, interspecific competition resulted in an increase in the time spent displaying and a divergence in the aggressive behavior of the native species toward conspecifics vs. heterospecifics. Inherent species recognition and higher aggressive behavior may limit species coexistence as they are expected to favor A. oculatus during territorial interactions with A. cristatellus.
5. While more studies are needed to understand the causes of these behavioral shifts and their consequences on long-term species coexistence, the present study highlights the role of behavior as a first response to interspecific interactions.

Raw data Dufour et al., 2020. Behavioral display of A. oculatus (robot experiement) and sex ratio