Diversity of warning signal and social interaction influences the evolution of imperfect mimicry

Abstract

Mimicry, the resemblance of one species by another, is a complex phenomenon where the mimic (Batesian mimicry) or the model and the mimic (Mullerian mimicry) gain an advantage from this phenotypic convergence. Despite the expectation that mimics should closely resemble their models, many mimetic species appear to be poor mimics. This is particularly apparent in some systems in which there are multiple available models. However, the influence of model pattern diversity on the evolution of mimetic systems remains poorly understood. We tested whether the number of model patterns a predator learns to associate with a negative consequence affects their willingness to try imperfect, novel patterns. We exposed week‐old chickens to coral snake (Micrurus) color patterns representative of three South American areas that differ in model pattern richness, and then tested their response to the putative imperfect mimetic pattern of a widespread species of harmless colubrid snake (Oxyrhopus rhombifer) in different social contexts. Our results indicate that chicks have a great hesitation to attack when individually exposed to high model pattern diversity and a greater hesitation to attack when exposed as a group to low model pattern diversity. Individuals with a fast growth trajectory (measured by morphological traits) were also less reluctant to attack. We suggest that the evolution of new patterns could be favored by social learning in areas of low pattern diversity, while individual learning can reduce predation pressure on recently evolved mimics in areas of high model diversity. Our results could aid the development of ecological predictions about the evolution of imperfect mimicry and mimicry in general.

Social information use about novel aposematic prey is not influenced by a predator's previous experience with toxins

“…An early study by Alcock () provided support for this idea, showing that fork‐tailed flycatchers were more likely to handle an Anartia amalthea butterfly, a palatable mimic of aposematic Heliconius erato , after observing a conspecific's attacks on the mimic. More recently, Bosque et al () showed that predator generalization might also be influenced by social conditions: after exposure to high model signal diversity, domestic chicks attacked imperfect mimics more if they were tested in a group, rather than alone. Social interactions among predators might therefore influence model‐mimic dynamics by both enhancing avoidance learning and generalization when individuals observe others consuming models (Mason & Reidinger, ), as well as increasing attack rates on both prey types when individuals observe others consuming palatable mimics (Alcock, ).…”

“…An early study by Alcock (1969) provided support for this idea, showing that fork-tailed flycatchers were more likely to handle an Anartia amalthea butterfly, a palatable mimic of aposematic Heliconius erato, after observing a conspecific's attacks on the mimic. More recently, Bosque et al (2018) showed that predator generalization might also be influenced by social conditions:…”

Numbers, neighbors, and hungry predators: What makes chemically defended aposematic prey susceptible to predation?

“…Fish are known to exhibit varying levels of aggressiveness toward their potential amphibian prey (Winandy & Denoël, 2015). Thus, the individual traits of fish may play an important role in shaping their predation of the defended prey (Nyström & Åbjörnsson, 2000), as has been observed in birds (Bosque et al., 2018; Exnerová et al., 2010, 2015). The abundance of nontadpole food also had a measurable effect on the B. bufo metamorph mass; heavier metamorphs emerged from the enclosures where the carp was provided with more fish feed.…”

Looking for Mimicry in a Snake Assemblage Using Deep Learning

“…Batesian mimicry occurs when palatable or harmless species evolve to resemble an unpalatable or dangerous model species and consequently gain protection from predators (Bates 1862). Mimicry is a canonical example of evolution through natural selection; it was already discussed by Darwin with Wallace (Darwin 1887) and still constitutes a proliferous field of research (Sherratt 2002;Nishikawa et al 2015;Joshi et al 2017;Bosque et al 2018). Nevertheless, some fundamental aspects of this defensive strategy remain poorly known-notably its frequency in plants and animals-mainly because detecting mimicry is no simple matter.…”