Right Okay, after some more research, I think I may have got a little closer, so I am looking for what you guys think about this. (It's taken longer, I had to re-do all my research)
This
could be an example of a
gynandromorph, this literally means means part female -
gyn and part male
andro. Right, stick with me here, this may take some explaining...
Lets start right at the very begining: All organisms that can reproduce sexually, so thats us, the birds, the bees and the butterflies etc
![Laughing :lol:](./images/smilies/icon_lol.gif)
(not bacteria and single celled organisms, for example) started life as a little single cell, they have a groovy name which is a
zygote (I won a game of scrabble with that
![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
). Basically a Zygote is a posh scientific word for a fertilised egg. From there this cell divides and divides into a few
stem cells (stem cells - these are unspecialised cells, they have not yet been 'told' whether they are going to be nerve cells, tissue cells, blood cells, sex cells etc). Then these stem cells specialise creating all the parts in the body, also can be known as a process called differentiation (not the mathmatical kind) - where all the cells follow developmental pathway that determines what it will become (a muscle cell, a nerve cell, a cell lining the intestine, etc.). They are no longer stem cells anymore, they have become
specialised. Then these specialised cells with divide into more of what they are specialised it. Take for instance and stem cell becomes a bone cell (I can explain how if you want me too, I thought it would be a bit long otherwise), that bone cell will divide into more bone cells.
Okay, still with me?
In humans,
the earliest cell divisions are indeterminate, which means that the developmental pathway is still flexible for all of the cells. So therefore the benifit to us is that, if one of these early cells happened to be destroyed, the end result is that it has virtually NO effect on development, since the other cells are still "flexible" in what they can become. So they are still Stem Cells at this point, they haven't specialised, no big deal if a few are destroyed, they weren't specialised in anything. This is in the very
Early Stages
However in insects and Lepidoptera cell division in, from the zygote on, is completely determinate, which means that decisions about what a cell will become are made with each division - they don't have stem cells like we do in the Zygote stage, ours divide then specialise, theirs divide and specialise at the same time.
This is how the divisions that determine what the cell specialises in and the order:
- First Division (of the Zygote) - determines Left and Right Sides
- Second Division - Determines back and front --> now there are four cells, Front Left, Front Right, Back Left, Back Right
- Third Division - Top and Bottom --> at this point there are eight cells, front upper Left, front Lower left etc
Say if an insect cell were to be damaged, you would end up with 7/8 ths of an insect - if it could develop that far, say missing the lower back left cell - missing the left lower part of the abdomen for example.
Right okay I hear you say, what has this got to do with Gynandromorphs?
As I mentioned previously, sex in humans and in Lepidoptera is determind by XX and XY system - not quite true, but I am keeping it simple (TRYING
![Laughing :lol:](./images/smilies/icon_lol.gif)
) see an earlier post where I explain the gender system!!
Now, quoted from earlier 'In gametes there are 23. This is because, when the egg is fertilised 23 chromosomes from the male + 23 chromosomes for the female = 46.' Bare this in mind again.
Right okay, now there can be a mistake in the copying of the Chromosomes to make the Gamates and this is called
non-disjunction This is where two copies of a particular chromosome do not detach from each other during cell division to make two gamates. (double helix, basically one side goes into one Gamete and the other side into another Gamete - when the egg is fertilised, the two halfs 'click' together again. I feel the need for a diagram, I will try and make one when I get back home), and the end result is that one of the cells will end up missing an entire chromosome, which is typically lethal to the cell. The other cell (that gets the unseparated chromosome) may be unaffected, or normal, though problems can occur in this cell as well.
This is where it really applies to the butterflies now!
Finally
If a non-disjunction occurs in an
X chromosome in an individual that is XX (male in butterflies/moths remember), that would mean that one of the cells in this division would end up with one X chromosome, while the other would end up with two (or three) X's. In other words, one of the resulting cells (and all cells that came from that cell) would be female, while the other cell (and its descendents) would be male. I will draw a diagram when I get home (tomorrow).
So, if you have a non-disjunction in an X chromosome in an XX individual during the first division of the zygote, then you will end up with an individual that appears half male (on one side) and half female (on the other side). Think of how the cells in the Zygote divide... (diagram to go here I think) This is called a
bilateral gynandromorph.
The Adonis is not a bilateral gynandromorph as both sides show both male and female charecteristics.
BUT The non-disjunction can occur during later divisions, giving you a smaller portion of the body/wings that looks like one sex and a larger portion that looks like another. It can even happen more than once during development, so that you end up with patches of female and male scattered around on the individual, resulting in what is called a
mosaic gynandromorph
Da! Da! - maybe what we have here? What would you all say? Due the nature of division of cells in the Zygote, this could result in the male and female genes being spread about a bit and becoming symetrical..
anyway, just a thought, I'd love to hear what others think to this, and well spotted Dave for pointing me in this direction!!
Em
P.S. if some or none of that made sense, just say and I will give it another bash at explaining, hopefully some diagrams will help out!