Heliconius butterflies are an excellent example of Müllerian mimicry, where phylogenetically distant species converge to nearly identical wing phenotype when occurring in sympatry. However, few studies have comprehensively addressed mimicry accuracy and variation in mimicry signals across the fitness landscape (which may comprise multiple fitness peaks). In this study, using analysis of colour quantification, wing size and shape, I investigate the extent of phenotypic resemblance between co- mimic species in multiple Heliconius mimicry rings. I found that wing size and shape do not contribute to mimicry. In contrast, colour phenotype is the main contributor, but some phenotypes are more accurate between co-mimics than others. This suggests the presence of multiple adaptive peaks within the same mimetic ring. In these butterflies, colour pattern is recognised as the main cue for mate recognition between species that are phylogenetically close, but when this cue is compromised alternative mating signals must evolve to ensure reproductive isolation and species integrity. The closely related species H. melpomene malleti and H. timareta florencia occur in the same geographical region, and despite being co-mimics, they display strong reproductive isolation. Here, I tested which cues differ between species, and potentially contribute to reproductive isolation. Wing colour pattern was indistinguishable between the two species, while the chemical profile of the males’ androconia and genitalia showed marked differences. Finally, I conducted behavioural experiments to study the importance of colour and chemical signals in mate recognition by females. I found that chemical blends and not wing colour pattern drive the preference of females for conspecific males. Also, experiments with hybrid males and females suggested an important genetic compound for both chemical production and preference suggesting that chemicals are the major reproductive barrier opposing gene flow between these two sister and co-mimic species. Altogether, these results agree with the idea that mimicry adaptation is a complex and dynamic process affected by more than one factor and that an effective combination of these signals (visual and chemical) is essential for intra- and interspecific communication processes in butterflies.
publication date
February 18, 2021 3:40 AM
Research
keywords
Analysis of the Batesian and Müllerian mimicry of the Heliconius
Butterflies of the genus Heliconius
Identification of distinctive chemical signals between species other than Heliconius
Identification system between comimetic butterflies
