Are all Y-chromosomes the same length?

[Nivelon]

I understand that the Y-chromosome is much shorter in length than the X-chromosome.

I understand that the Y-chromosome is slowly, very slowly, getting shorter.

In humans we have several different haplogroups of the Y-chromosome.

Are all of the haplogroups the same length?

Are all of the PAR regions of the same length and in the same place?

Could length of the Y-chromosome affect the health of the gametes?

[TheVat]

IIRC, Y does vary somewhat between human males, though that is more in the junk coding than in the functional developmental genes.

Groups of genes that govern fertility and normal development are not going to change much in their number between individuals, which is what you would expect given their critical roles in those processes.  Any shift in number of those genes would likely be lethal or at least cause sterility and so would not be passed along. 

As for the slow shrink theory, I think that is based on a linear extrapolation that has been largely discredited.  

[CharonY]

55 minutes ago, Nivelon said:

I understand that the Y-chromosome is slowly, very slowly, getting shorter.

If you are talking about the human (as in the extant species) Y-chromosome, this is not correct. The studies looking at gene loss are rough and look at degeneration over millions of years. Shorter estimates are AFAIK extrapolations of the the larger calculations. Short-term comparisons do not see any gene loss between close ape species, I believe.

There is more variation in the non-coding regions, but this is also not a linear decline. Recently, the Y-chromosome has been fully sequenced and there is marked difference among individuals. These are mostly caused by repetitive regions, which vary in the number of duplications and sometimes losses of them.

 

Edit: cross-posted.

[Nivelon]

1 hour ago, CharonY said:

 Recently, the Y-chromosome has been fully sequenced and there is marked difference among individuals. These are mostly caused by repetitive regions, which vary in the number of duplications and sometimes losses of them.

Is there a free resource where I could read more about this? I am trying to chase down something for a story I am writing, so the more I know the better. Any study that takes an objective look at different lengths among individuals, especially if it relates to health. I found one picture, but I believe they did not study a wide variety of Ys.