The wild one are a little harder and you get a lower tone
 i had heard this as well . not sure i 100% agree though .
What I would agree with is that the thickness of the call dictates how the vibration travels  and thus does produce a little different tone .
 A few years ago I  made a lot of wing bone calls for local folks . Some out of wild turkey wings  others from domestic turkey wings .
What I found was that the length of the bone used for the mouth piece dictated the tone of the  call . IE a long bone achieved a deeper call while a short bone made a high pitch call . 
 I made one I called a blaster !!.
 I actually did that by accident as the long bone had been broke ,  so when I finished , the call was only about 3 inchs long .
  It was loud and high pitched  beyond belief .. I used to keep it hanging in my shop .  Then one day I got this idea .
All we are really doing is making a musical interment like a trombone or trumpet, both of which  produce tones by  the very same application . IE the vibration from the lips of the musician. The pitch of each individual note is then changed  by lengthening  or shortening the distance that the sound travels through the  tubing . That sound is then magnified by the bell of the interment.    
  Then I got to thinking . OK , if this was indeed the case , then like  musical instruments, each  will have its own distinct quality of sound  that unique to itself . Very much like  each individual bird had a distinct tune to its call / voice 
 So I started carrying two different pitched calls  while hunting , alternating my calling  between  the calls . That worked very well . So well in fact that when my hunting partner and I go out , we care 2 calls each . So we end up sounding like for different hens cutting to each other .
 I can tell you that  if the toms are hot , the result is  un believable .
Sadly I broke the little Blaster  one fall . it was made from a domestic turkey wing and thus not as strong as  a wild wing call . I had it hanging from the rear view mirror in my scout and while going over a rough section of road the call bounced of the windshield and broke .  I have never gotten around to making another