Why can't we all just get along? Interspecific aggression in resident and non‐residentPodarcis melisellensislizards

Abstract

Interspecific aggression is thought to be driven by competition over either shared resources or mates, with the latter facilitated by mistaken or poor species recognition. However, such aggression may potentially also be modulated by other factors, including residency in territorial species. We tested the relative strengths of intra‐ and interspecific aggression in the lacertid lizard Podarcis melisellensis by introducing males to both the territories of conspecific males and the territories of a sympatric lacertid, Dalmatolacerta oxycephala. We also conducted reciprocal introductions to test the effect of residency on interspecific aggression in P. melisellensis. Our results show that P. melisellensis exhibit significantly more aggression towards D. oxycephala than towards conspecifics, even though these two species do not closely resemble one another and do not exhibit extensive overlap in diet preferences. We also found an overall effect of residency on behavioural measures of aggression, as well as a clear increase in interspecific aggression towards D. oxycephala in resident relative to non‐resident P. melisellensis. These results show that interspecific aggression between sympatric species can exist in the absence of breeding competition and with little resource overlap.

Do interspecific interactions between females drive shifts in habitat use? A test using the lizardsAnolis carolinensisandA. sagrei

“…Furthermore, the shift in habitat use and lower population densities of A. carolinensis in the presence of A. sagrei (Losos & Spiller, ; Edwards & Lailvaux, ) is consistent with what one might expect if these species are competing over habitat resources. On the other hand, theory also predicts that interspecific interactions are likely to be less intense and physically aggressive than intraspecific interactions, especially in situations where mistaken identity and interbreeding are unlikely (Brunswick, ; but see Lailvaux, Huyghe & Van Damme, ). Both anole species exhibit female‐defence polygyny, but given that male green and brown anoles are unlikely to mistake each other for the same species, and that the rate of inbreeding between these species is probably extremely rare if it occurs at all (Losos, ), our results therefore suggest that habitat separation between these two species is not driven by interspecific aggression between males, despite the appearance of competitive exclusion based on male habitat data (Hess & Losos, ).…”

Heterospecific aggression bias towards a rarer colour morph

“…In particular, not only are individuals and morphs with such colours commonly dominant in interactions among conspecific individuals, as in the Gouldian finch ( [53] and references therein), but brightly coloured individuals may also be challenged more aggressively, as has been shown in reptiles [54] and fish [55,56], including cichlids [57]. Indeed, although niche overlap has been offered as one of the main predictors of the level of heterospecific aggression [22], it does not always explain its intensity, as in lacertid lizards [58]. In cichlids, it also remains possible that because the dark individuals are-and historically have been-much more numerous [26,29,59], H. nicaraguensis territory holders may be more familiar with this intruder type and, because of learning effects such as the 'dear enemy effect' and stimulus habituation [60,61], react more intensively to less familiar gold individuals.…”

Aegean wall lizards switch foraging modes, diet, and morphology in a human‐built environment

“…While this pattern in maximum bite force does not follow the predictions from previous interspecific foraging mode studies (Herrel et al, 2004;Vanhooydonck et al, 2007), it is consistent with a previous study showing P. erhardii bite force is less related to diet and more related to the local intraspecific competitive landscape . While tests of this hypothesis remain to be conducted, other studies have documented significant intraspecific aggression in closely related active foraging Podarcis species (Lailvaux, Huyghe, & Van Damme, 2012;Pafilis, Meiri, Foufopoulos, & Valakos, 2009), which may explain the proportional increase in bite force among the active foraging male populations at nonwall sites.…”