[Odonata-l] black in dragonflies

Thu Dec 6 08:16:24 PST 2007

Hi all,

Genetic research by Erik Pilgrim has shown that "nigrescens" populations from Ireland and Norway fall within the global genetic variation of Sympetrum striolatum. I think a paper on this is in press or has just appeared.

Cheers, KD

Klaas-Douwe "KD" Dijkstra
Curator of invertebrates, National Zoological Collection of Suriname, University of Suriname, P.O. Box 9212, Paramaribo, Suriname
Research associate, National Museum of Natural History Naturalis, P.O. Box 9517, 2300 RA, Leiden, The Netherlands
e-mail: dijkstra at nnm.nl <mailto:dijkstra at nnm.nl> 
website: http://www.barakken.nl/kddijkstra/ <http://www.barakken.nl/kddijkstra/> 
photos: http://www.flickr.com/photos/kiskadee/ <http://www.flickr.com/photos/kiskadee/> 

________________________________

From: odonata-l-bounces at listhost.ups.edu on behalf of David Goddard
Sent: Thu 12/6/2007 1:00 PM
To: Nick and Ailsa Donnelly; 'Bob Glotzhober'; 'Odonata List Server'
Subject: Re: [Odonata-l] black in dragonflies

Hi All,
         Following on from Nick's observations, over here in the UK we have the question of Common Darter Sympetrum striolatum and the Highland Darter Sympetrum nigrescens are they the same species but with more black for the Highland Darter or are they indeed different species.

Regards
David Goddard

	----- Original Message ----- 
	From: Nick and Ailsa Donnelly <mailto:tdonelly at binghamton.edu>  
	To: 'Bob Glotzhober' <mailto:bglotzhober at ohiohistory.org>  ; 'Odonata List Server' <mailto:odonata-l at listhost.ups.edu>  
	Sent: Wednesday, December 05, 2007 8:24 PM
	Subject: Re: [Odonata-l] black in dragonflies

	As an additional note, the more northern members of widespread species commonly have more extensive black than their more temperate cousins.  An example that struck me at the time was Enallagma ebrium, which in Northern Quebec is so black as to cause at least one person (not me) to think it might be a new species. (not me)

	Nick Donnelly

________________________________

	From: odonata-l-bounces at listhost.ups.edu [mailto:odonata-l-bounces at listhost.ups.edu] On Behalf Of Bob Glotzhober
	Sent: Tuesday, December 04, 2007 1:38 PM
	To: Odonata List Server
	Subject: [Odonata-l] black in dragonflies

	I am looking for data, opinions, thoughts and ideas on why so many dragonflies have black as a major color. This initially hit me last summer when a couple of us locally were working with 3 plus species of Macromia on the Big Darby Creek near Columbus. Since then, I've been invited to talk to a bunch of folks as a part of our state's wildlife diversity conference - and the entire conference theme is "Back in Black".  Obviously, an emphasis will be around the resurgence of black bears in Ohio, but also other "black" wildlife including cormorants, black vultures, the (melanistic) Lake Erie Water snake, and others - including black dragonflies.

	While my emphasis will be on the diversity of such critters and their ecology, I want to spend a little time discussing the thought of why so many are black. To launch things (my apologies to Tom) I am inserting a communication from Dr. Tom Schultz at Denizen, who has worked on colors in Odonata before. This is a basic good start - and maybe it will stimulate some further thought and discussion within this group. I eagerly await to hear not only hard data but off-the-wall theories as well. 

	Here is Tom's correspondence:

	"Bob,

	I have given this a little bit of thought.  The combination of yellow and black is as conspicuous as any Odonate coloration can be, especially if the visual system of the insect is trichromatic with sensitivities to UV, blue and green (like bees).  The striping provides important contrast that enhances detestability; consider the difference in how C. erronea looks compared to S. linearis when each patrols the same shaded stream.  In dark forest understory black and yellow would be the color pattern of choice. In light flecks, yellow is a conspicuous color  because it reflects the filtered green-yellow light without matching the green background. However, when flying in and out of light flecks the broken pattern of Cordulegaster should make it hard to detect.    

	The eyes may be part of the color pattern that  these dragonflies use to attract mates or identify themselves, but they should also boost the reception of the wavelengths they reflect (e.g. green).  No research has really been done on the roles of color in odonate eyes, but it is a reasonable guess that the emerald green eyes may function like a tapetum in vertebrates.  

	There are only three studies using electrophysiology to determine the color vision of an odonate species.  Two bluets are know to have receptors for UV, blue and green.  It has been shown that one red libellulid species has an additional  red photoreceptor.

	Tom"

	Bob Glotzhober

	====================

	Robert C. Glotzhober             614/ 297-2633

	Senior Curator, Natural History         bglotzhober at ohiohistory.org

	Ohio Historical Society         Fax: 614/ 297-2546

	1982 Velma Avenue

	Columbus, Ohio  43211-2497

	Visit the website of the Ohio Historical Society at:

	  www.ohiohistory.org <http://www.ohiohistory.org/>  and check out our online collections catalog.

	See or purchase Dragonflies and Damselflies of Ohio or the Cedar Bog Symposium II at OHS's new E-Store:  http://www.ohiohistorystore.com/ 

	Visit the Ohio Odonata website at:  http://www.marietta.edu/~odonata/index.html

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