So in birds, sex chromosome arrangement is a reverse of what we have in humans. Their males are ZZ and the female is ZW. Which is why only males appear from this parthenogenesis.
- The fact that females are defined by unmatched sex chromosomes rather than matched ones means that in haploid parthenogenesis (a split and rejoining of a single half of a genome, rather than fertilisation by male and female sex cells), the resultant sex cells are either ZZ (vialble male) or WW (nonviable "super-female").
- Parthenogenesis in mammals on a similar basis isn't possible as the umatched chromsome is found in males (giving a viable XX female) ... but without an ovum or womb. A self-replicating female egg would be XX.[1] There's ... some research into parthenogenesis in mammals, and at least one apparent observed instance.[2]
- In the case of Avian or similarly Z/W species, parthogenesis is a potentially viable option for resuming sexual reproduction of a population in which all males have been lost. For mammallian populations, not so much. In any case, there'd likely be an extreme genetic bottleneck.
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Notes:
1. Religious implications for spontaneous mammalian parthogenesis resulting in male offspring are left ... undiscussed.
The mechanisms of parthonenogensis aren't fully characterized, but at a high level, it occurs in a secondary oocyte during meiosis II -- the oocyte only starts out with a Z or W chromosome.
ZW is less likely because normally parthenogenesis starts with a haploid egg cell (Z or W) that undergoes meiosis alone, copying its own chromosomes - becoming ZZ if it started as Z and WW if it started as W. WW is normally not viable, just like YY in mammals, so the most likely case of parthenogenesis by far is ZZ, male.
It's a "clone" of half of the mother's DNA. The mother had random inheritance from its parents. So it's not a clone of the grandparents, but it's a copy of (half of the) mix that the mother had.
No, it's more like an extreme case of in-breeding.
On the other hand, if a mammal were to produce a viable fertile offspring through parthenogenesis, then that offspring would be a clone of it's mother.
Meant to say: mammal mother produces a viable offspring through parthenogenesis, which in mammals would be XX, a daughter, an in-bred individual. Now, if that daughter produces another daughter through parthenogenesis, then this second generation of parthenogenesis individual would be a clone of the first generation daughter.
