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<excerpt>My=A0knowledge of syrphids
Steve Shaw wrote:
> Chris, Angus, others...
> Since the mimicry is superficial, extending to external bodily
> appearance and perhaps to some behaviour, it is unclear why mimicry is
> not distributed more or less evenly among other groups of flies, or
> why it is so common in syrphids and strats: it is hard to imagine that
> either group would have had some special 'preadaptation' not found in
> other families of fly, that would make mimicry a likely evolutionary
> strategy for the whole family -- at least I can't think of anything.
Hi Steve & All, Oct 20, 2006
I don't see any great mystery here. Mimicry to resemble potential
danger (bees & wasps) is a special case of widespread adaptations;
disguise to resemble something else [e.g. leaf, thorn, twig, sea weed,
seed, dirt, flower, background, danger, disagreeable taste & toxin to
name a few that come to mind offhand].
Evolution is a random walk; either in small circles, into greener
pastures or off of a cliff (metaphorical cliff in the case of flying
animals). In the case of relatively large insects, that spend
appreciable time, in full view, working flowers (Syrpids and
Stratiomyids), is it not reasonable that chance modifications, such that
some strains resembled dangerous insects, would confer some survival
value ? If all flies had taken this turn, then yellow with black would
have come to mean 'harmless food' and bees and wasps would have assumed
some other coloration. In addition, many late summer flowers are yellow,
so yellow has a certain backgroud value.
Yours truly, Dave Webster, Kentville
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