Races of Heliconius melpomene and Heliconius erato mimic each other in South America and those 2 species are in the same genus (though not sister species), suggesting that relatedness per se does not disqualify species from being mimics.  However, mimicry often involves evolutionary changes in color pattern to match those of the model.  If the similarities between suspected co-mimics are due to the fact that both retain an ancestral color pattern (such as the black and white bands on the wings of many Nepthis, Athyma, Limenitis, etc.), it is harder to argue that the similarity between the species is functional, particularly when there is no evidence of unpalatability.  Are you sure that birds are the appropriate visual predators to test for unpalatability in this system?  Could lizards or predatory insects be important in the context of the environments in which you are working?  The palatability of food varies enormously between different taxonomic groups of predators. Finally, if the black and white bands are ancestral and there is no unpalatability, you may be seeing sexual selection related to female choice driving male color pattern evolution to derived states, and the female color phenotypes, which  are frequently more conserved than male phenotypes in this context are retaining their ancestral phenotypes.  Female choice in different Athyma and Auzakia species may prefer different color pattern phenotypes in each species, allowing closely related species to remain reproductively isolated, even though they co-occur and occupy similar niches.  Good luck with your project!  JMM

Thank you very much for the detailed reply. Yes, I am familiar with the pitfalls you refer to and birds do form an important part of the system, judging by beak marks on wild individuals. The thing that raises doubts about the male pattern being female choice driven is that the females look remarkably similar to their proposed 'models' (Neptis) in flight, while the males are not easy to confuse. Let us see what time brings in.. I have been pondering this for over 20 years now...

Sexual selection could be pushing the males away from the ancestral colour pattern phenotype that natural selection prefers due to mimicry. The behaviours that you observe that enhance the visual mimicry may only be effective in females that already closely resemble the models.  So the female mimicry colour pattern may be ancestral, but female mimicry behaviour could be derived….  Again, best of luck in sorting this out.

It seems to be generally accepted that species within the same genus can mimic one another, even if the patterns are derived from a common ancestor (the defended species of Zygaena moths in the Palaearctic are a good example). The question might be not so much "are they mimics?" as "has the pattern resemblance evolved by convergent evolution, parallel evolution, or simply retention of the ancestral pattern [or whatever very refined cladistic terms one wants to denote those processes!)?". In the last case of course natural selection in favour of mimicry may have prevented divergence.

Lincoln Brower proposed that even members of the same species could mimic one another: that individual Monarch butterflies which lacked the defensive alkaloids were in effect Batesian mimics of those individuals in the population which had succeeded in obtaining the compounds from the hostplant.

Thank you very much for your comments, Dr Turner. I am familiar with Dr Brower's proposal regarding Batesian mimicry within plexippus. However, there is always one distasteful model with either a distasteful mimic or a palatable mimic. When both or all parties are palatable, then the problems begin...

It is true that the pattern resemblance, behavior, seasonality, habitat preferences, which all match, might have evolved either by convergent or parallel evolution or it is an ancestral pattern... since I am sitting in the backwoods, I am unaware of any line of questioning that might resolve these questions one way or the other. May I impose on you for a possible line of enquiry that could probe this matter further?

Dr Smetacek: yes indeed. I apologise, I was responding only to your headline question not attempting to answer your detailed query.

"Palatable" species can mimic one another as a result of there being no clear distinction between a nutrient and a toxin (something Iearned from a collegue who researched on animal nutrition). All nutrients indeed are potentially toxic. If anyone following these questions doubts that, they can demonstrate it experimentally on themselves, by eating a diet very high in fat (NO DON'T TRY THIS AT HOME, PLEASE: YOU WILL END UP WITH TYPE 2 DIABETES IN A REMARKABLY SHORT TIME!! A very high sugar diet will rather less rapidly make you overweight and will quite probably trigger ischaemic heart disease.) Same goes for any polyphagous predator.

Prey are then partly protected from predation if they are at high population numbers, not simply because the predators become satiated, but because the predators must switch prey in order to avoid the toxic effects of consuming too much of the particular compounds of that prey species. This generates the possibility for mimicry between "palatable" species (palatable in the sense that predators will readily eat them as part fo their occasional or regular diet): a rare palatable species will benefit from superficially resembling a common palatable species.

This was originally proposed, I think without the nutritional theory, by the Kenyan lepidopterist VGL van Someren. There's an exploration of some of they dynamics in

J.R.G. Turner and M. P. Speed 2001 How weird can mimicry get? Evolutionary Ecology 13, 807–827, in the context of shared toxins generating mutual protection wih or without colour pattern resemblance, and citation-tracking for that paper will produce a further, follow-up literature.

I will try and generate a transmissable pdf of this paper. It would be easier for me to send this by email than through this website, if you can send me an email address to [email protected], when I can also try to do the same with the various other publications mentioned in your direct messages.

Just one more thing: I am somewhat out in the boondocks, technologically speaking, myself here. My very very old computer (just over six years old!) is starting to malfunction, possibly as a result of the withdrawal of support for windows xp ). If I suddenly go "off air" it's not that I have become unfriendly, but that I am waiting either to solve the problem or to design and order a new computer.

Best wishes JRGT