NABOKV-L post 0007045, Thu, 7 Nov 2002 13:57:26 -0800

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Fw: More on Nocturnal Color Vision
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----- Original Message -----
From: Johnson, Kurt
To: D. Barton Johnson
Sent: Thursday, November 07, 2002 1:04 PM
Subject: RE: More on Nocturnal Color Vision


This is a note regarding the implications of an example I believe Nabokov discussed. He was fascinated by the translucent "windows" in the wings of the large Saturnid moths and in some other "leaf mimics etc." and, in one case (where this window had a venation line running through it) speculated that this kind of "detail" with regard to what it appeared to look like to him, certainly could not have come from directional (natural) selection alone. With the information now available on nocturnal color vision (by starlight!) indicated in moths, the following comments appear quite relevant to the situation of adaptive (selectable) value in the translucent "windows" on wings of Saturnid , or other, moths. The arguments can be seen below:

Whereas,

l. As is well known in the scientific literature, insect sensory receptors, and the patterns of behavior ("released patterns") they trigger, usually work on an "all or none" basis. That is, a specific kind of reception of sensory data is linked to specific kinds of patterns of behavior that can be released/performed; and

2. The long and quite detailed paper (still unpublished) I gave at the Harvard ALA meeting noted that scientific papers document that insects can pick up [and thus "look for" regarding their behavioral patterns, recognition patterns etc.] specific wavelengths, frequencies, and resonanace patterns of direct and/or reflected light, most often in the UV spectrum; and

3. It is well known in diurnal (day-flying) Lepidoptera (butterflies) that behavior and recognition patterns relate to reflected UV from the wings that human beings cannot see (Scientific papers demonstrating this use visible photographs of these UV signals from the butterflies wing by using UV sensitive film. These UV signals are seen as PATCHES and PATTERNS on the wings, just like what we see on the wings are color or colored patterns etc. But most of the UV patches ARE NOT in the same places on the wings as the visible light patterns);

Thus,

If, according to this new information, UV light from starlight creates a "visible" spectrum for color vision by moths at night, it is quite possible that the translucent "windows" on the wings of Saturnid , or other, moths function as a differential channel for the conveying of that light (from the environment, i.e. starlight) through the wing and "out" to other moths sensory systems (for recognition or other purposes etc. as is common with sunlight and diurnal Lepidoptera). The "windows" may therefore be one of the channels in the wing involved with this light-related communication. In the case of a vein running through the translucent "window", and sensitivity of insect recognition to wing beat rate (well documented in the scientific literature) the vein might function as a modality regarding the frequency of light that is let through the translucent "window" etc. Thus, there appears now to a possibly large range of actual adaptive (and thus selectable) functions that the translucent "window" in the wings of Saturnid , or other, moths could be performing.

best
Dr. Kurt Johnson