[Leps-l] Eastern Tiger Swallowtail intermediate morphs

[David Hamilton Cox]

 In the May 2016 issue of the "Potomac Appalachian Newsletter", available here:

https://urldefense.proofpoint.com/v2/url?u=http-3A__www.patc.net_PATC_Library_Newsletter-5FArchives.aspx&d=CwICAg&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=tVAKMFPe3UCcsMWUFXo0FeX0xe1JUAj77B74DAI3DKI&m=nrCHxoOnUXnPVsa6s8KQTU8N2CkpZ_0Jd6Vrln758rs&s=KXFWodLt7AXdJeLkv7rvmlicJ3RBvmQn5uo-pX_u2wE&e= 

 an articled entitled "HIKER'S NOTEBOOK: EASTERN TIGER SWALLOWTAIL BUTTERFLY 
THE LADY AND THE TIGER" by William Needham, starting on page 7, states on
page 9 that:

"Recent genomic research of this phenomenon has revealed that it is a very 
simple process; melanism is controlled by a single gene that converts the 
yellow background to black."

 I occasionally see female Tiger Swallowtails that appear to be intermediate
between the yellow and black morph, such as this one I photographed in Madison 
County, Virginia on April 15 of this year:  https://urldefense.proofpoint.com/v2/url?u=http-3A__www.nyx.net_-7Edhcox_tiger.jpg&d=CwICAg&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=tVAKMFPe3UCcsMWUFXo0FeX0xe1JUAj77B74DAI3DKI&m=nrCHxoOnUXnPVsa6s8KQTU8N2CkpZ_0Jd6Vrln758rs&s=K5pLHggxDhG64gUBuYLKyQz7tMzOXQ15jArX_28pcvM&e= 

 How can this partial change occur if only one gene is involved? I realize
I am probably displaying a rather complete lack of how genes work but 
thought I would at least ask.

-David Cox