>It is important to note that, statistically, neither of the examples of how to do parthenogenesis will >result in offspring that are completely 100% genetically identical to each-other.Mechanisms >include spontaneous mutation (rate of roughly 1/billion nucleotides in eukaryotic cells, so >roughly 6 per cell division in humans!... mostly neutral and/or corrected automatically, >except when making gametes), independent assortment of chromosomes in Meiosis I, >crossing over in Prophase I, etc.
The mechanism of parthenogenesis in whip-tailed lizards is such that the only source of genetic variation is spontaneous mutation (this mechanism involves a doubling of the chromosomes just before meiosis starts). This is presumably also the mechanism that occurs in geckos, although to my knowledge nobody has confirmed this. If so, however, the offspring of a parthenogenetic gecko will be just as genetically identical to each other as are human identical twins, and they will also be the same as their mother.
In fact clones that result from parthenogenesis, as well as human identical twins, are more genetically similar to each other than human-created clones such as Dolly the sheep. This is because our way of making clones involves copying the genetic material contained in the nucleus only. The genes in the mitochondria (special organs in every cell which produce energy) come from the donor egg that the copied nuclear material is implanted into. Parthenogenesis, however, copies these mitochondrial genes as well (there aren't many of these, 60 in humans compared with something like 100,000 nuclear genes).
And of course, even if two animals are genetically identical, this doesn't necessarily mean they will look or behave identically to each other. I currently have identical twin Bynoe's Geckos (Heteronotia binoei, another parthenogenetic gecko) hatching out and they differ subtly in back pattern and even in the number of labial scales, despite being incubated under identical (?) conditions.
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Michael Kearney
School of Biological Sciences
Building A08
University of Sydney
NSW, AUSTRALIA, 2006
[EMAIL PROTECTED]
ph + 61 2 9351 7661
fax + 61 2 9351 5609
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