Interspecific differences in chemosensory responses of freshwater turtles: consequences for competition between native and invasive species

Abstract

The red-eared slider (Trachemys scripta elegans) is an introduced invasive species in many Mediterranean countries that is displacing the populations of native endangered Spanish terrapins (Mauremys leprosa). However, it is relatively unknown how potential competitive interactions could be taking place. In many freshwater turtles, semiochemicals from different glands might facilitate species and sex recognition. We hypothesized that chemosensory detection of competitor species might affect space use and habitat selection by freshwater turtles. We analyzed whether T. scripta and M. leprosa turtles recognized chemical cues from male and female conspecifics and heterospecifics in water. We compared time spent by turtles in clean water pools vs. water pools containing the different chemical stimuli. Introduced T. scripta did not avoid nor prefer water pools with chemical stimuli of native M. leprosa terrapins, which might favor the expansion of the invasive species. In contrast, M. leprosa preferred water with chemical stimuli of conspecifics and avoided water with chemical cues of T. scripta, which suggests that chemical cues could be used by native M. leprosa to avoid water pools occupied by introduced T. scripta. We suggest that this avoidance behavior of native M. leprosa may be one of the causes that contribute to the observed displacement of their populations by invasive T. scripta.