Visual cues elicit differential aggression towards female and female mimics in the corkwing wrasse

Abstract Alternative reproductive tactics (ARTs) are consistent intrasexual differences in behavior that maximize reproductive success through different means. In corkwing wrasse (Symphodus melops), smaller males mimic female visual morphology (hereafter sneakers) to steal fertilizations from nest-building parental males (hereafter nesting males). We investigated whether this visual mimicry effectively deceived 47 nesting males across 4 sites by quantifying 2 agonistic responses (attack latency and attack frequency) to models depicting unfamiliar females, sneakers and rival nesting males. Contrary to expectations, nesting males exhibited faster agonistic responses towards female models, with lower attack latencies compared with both male types. Additionally, the relationship between model type and attack frequency varied between sites, with reduced attack frequencies at sites subject to increased levels of anthropogenic disturbance. These results provide evidence that nesting males can visually discriminate between females and sneakers even in the absence of behavioral cues, suggesting that visual mimicry alone may be insufficient for successful deception. This highlights the need to investigate alternative sensory modalities, such as behavioral mimicry, to explain the successful reproduction of sneaker males and the maintenance of ARTs in this species.