Allopatry, competitor recognition and heterospecific aggression in crater lake cichlids

Abstract

BackgroundAggressive behaviour can have significant evolutionary consequences–not only within species, but also in the context of heterospecific interactions. Here, we carried out an experimental field study to investigate the importance of phenotypic similarity on levels of aggression between species whilst controlling for familiarity effects using manipulated allopatric stimuli. Specifically, we investigated aggressive responses of territory holding males and females in two species of Neotropical cichlid fish, Amphilophus sagittae and Hypsophrys nicaraguensis, that differ in their phenotypic similarity to our allopatric stimulus species, Amphilophus astorquii.ResultsWe found that, independent of phenotypic similarity (and correlated phylogenetic proximity) between the territory holders and intruder, territorial aggression was not adjusted in relation to allopatric intruder colour markings that are associated with different levels of threat and known to provoke different responses in a sympatric setting. We also found that males and females did not differ in their overall patterns of aggression adjustment towards intruder cues. Nevertheless, the two focal species, which share the same breeding grounds and external threats, exhibited different sex roles in breeding territory defence.ConclusionTogether with earlier studies assessing hetrospecific aggression in sympatry, our current results highlight the importance of coevolution and learning in species interactions.

Expanding the concept of social behavior to interspecific interactions

“…For example, neotropical cichlid fish that share breeding grounds with heterospecifics are more aggressive toward heterospecific nonbreeding individuals, that pose a threat to their offspring, than to heterospecific breeders, using body coloration as a recognition cue of heterospecific breeding status (Lehtonen et al, 2010, 2015). Interestingly, when exposed to manipulated territorial intrusions individuals of allopatric populations do not show an adjustment of their aggressive response in relation to heterospecific color markings that are associated with different levels of threat (Lehtonen et al, 2016), highlighting the importance of coevolution and learning in the categorization of heterospecific interactants. Interestingly, the same social signal can be differentially perceived by the different sexes of another species.…”