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Fly with ant-mimic wings

#1
Magical Realist Offline
Several readers have called my attention to yet another amazing case of mimicry, this time in a tephritid fly (the “true” fruit flies). Most people became alerted to this by a semi-viral tw**t by Ziya Tong, which notes that “Goniurellia tridens is a 3-in-1 insect,” and that the photo below was taken by Peter Roosenschoon in Dubai. Roosenschoon is a conservation officer at the Dubai Desert Conservation Reserve.

Those aren’t ants bedecking the fly’s wings; they’re the normal wing markings of this species. But why would a fly have antlike markings on its wing? [UPDATE: Note comments at bottom where an ant expert and two others (including Matthew) think that these are spiderlike markings. I’m coming around to that point of view.]

The issue is discussed in a New York Times‘s “Dot Earth” column by Andrew Revkin, which refers back to the original article in the original article by Anna Zacharias in The National, a United Arab Emirates newspaper. Zacharias describes it:

The image on the wing is absolutely perfect,” says Dr Brigitte Howarth, the fly specialist at Zayed University who first discovered G tridens in the UAE. [JAC: the species has been known since 1910, and is found in the Near and Middle East, Asia, and Asia.]

. . .In the UAE alone, 27 picture wing species are known. Some have wings bearing simple shapes but others, like G tridens, are far more complex.

Dr Howarth first saw G tridens on an oleander shrub in northern Oman. “I was looking at the stem of the leaves and I noticed that there were some insects crawling around. When I sort of honed in I started to notice what I thought was a couple of ants moving around.”

At first she suspected an infestation on the fly’s wings. “But it was so symmetrical that I thought, ‘oh this is not possible’. When I got it under the microscope I realised that these were insects painted onto the wings.”

In contrast to its wings and brilliant green eyes, the fly’s body is a dull greenish grey – “almost cryptically coloured,” says Dr Howarth – that blends into the leaves where it is found

Here’s a photo (uncredited) of a pinned specimen from The National:


[Image: byoqw4tceaalsqd.jpg?w=516&h=387]
[Image: byoqw4tceaalsqd.jpg?w=516&h=387]



But why the ant markings? Howarth, interviewed by Zacharias, explains:

When threatened, the fly flashes its wings to give the appearance of ants walking back and forth. The predator gets confused and the fly zips off.

That doesn’t make a lot of sense to me. Why doesn’t the fly just “zip off” by flying away when it sees a predator? Confusing a predator by waving your wings just wastes time. Now some tephritids have spider-like markings on them, and that makes more sense. Apparently the predator is a jumping spider, and when it sneaks up on a fly, it sees the spider markings, mistakes them for another spider of its species, and displays to it. That display gives away the spider’s presence, allowing the fly to get away. But I can’t see this happening with ants."

https://whyevolutionistrue.wordpress.com...mic-wings/
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#3
stryder Offline
(Apr 24, 2015 11:00 AM)Mr Doodlebug Wrote: Tw**t?

From the source somewhere down in the comments that followed:
Quote:

[Image: be3e2ea055208334e283e90ce260e7ba?s=48&d=identicon&r=G]
[Image: be3e2ea055208334e283e90ce260e7ba?s=48&d=identicon&r=G]

markbellis
Posted November 6, 2013 at 1:54 pm | Permalink
Why are tweet and twitter rendered tw**t and tw*tter on this page?


[Image: 8b83f8fbcd1881ebc3d0e3ac9c4af808?s=48&d=identicon&r=G]
[Image: 8b83f8fbcd1881ebc3d0e3ac9c4af808?s=48&d=identicon&r=G]

Diana
Posted November 6, 2013 at 6:09 pm | Permalink
Those are some of the verboten words.

Looks like some mess-up on their Wordpress site suppressing "Twitter" from being stated. (Not a bug on this one, although there is only one censored word that only exists as a test currently and it doesn't star the word it replaces it.)

As for the the actual bug in the topic. It's rather interesting to try and work out how it's possible to evolve the camouflage, did it just decide one day that it would be good to have something to scare off predators? (following the lines of squid, octopus and chameleons) or was it a slow process that possibly took many gestations/lifecycles?.

It's obviously something more subtle than a complete physical adaptation like a stick insect.

Does it's wings work similar to photosensitive film, where the fly bakes it's own shadow into it's wings?

They're the myriad of questions I'd ponder, rather than is it suppose to be an ant or a spider on the wing?
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#4
Mr Doodlebug Offline
There is a criticism of the ant theory, in that other species have similar markings, but they don't look like ants.
Almost certainly, it is a distraction, but perhaps not mimicry.
It is what the species looks like to predators which is of ultimate importance.
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#5
Magical Realist Offline
One can imagine an initial mutation on the fly that results from brown blobs on the wings. This trait might be favored because they merely suggest an ant or a spider near the fly. Of these new blob marked flies, a slight advantage is given to those whose blob looks more like a ant or spider. So these flies get selected for survival. Eventually over thousands of generations the resemblance to an ant or spider is so honed thru favoring that shape that it results in the present species. It is the meticulous craftsmanship of natural selection working over hundreds of thousands of years. Notice the ant/spider shape even has eyes. It seems to us impossible. But I'm thinking we underestimate the accumulative effect of thousands of generations of mutations on the survival of a species. The slightest advantage of one blob shape over another in being mistakable for an ant or spider. Moths have accomplished the same sort of protection with owl-like wing markings:


[Image: Moths-and-Owls.jpg]
[Image: Moths-and-Owls.jpg]

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