Tue Sep 11, 2012, 11:17 PM
eppur_se_muova (26,280 posts)
Virgin births discovered in wild snakes (BBC)
By Jeremy Coles
Reporter, BBC Nature
Virgin births have been reported in wild vertebrates for the first time.
Researchers in the US caught pregnant females from two snake species and genetically analysed the litters.
That proved the North American pit-vipers reproduced without a male, a phenomenon called facultative parthenogenesis that has previously been found only in captive species.
Scientists say the findings could change our understanding of animal reproduction and vertebrate evolution.
It was thought to be extremely rare for a normally sexual species to reproduce asexually.
So ... Jesus snakes ?
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Virgin births discovered in wild snakes (BBC) (Original post)
Response to eppur_se_muova (Original post)
Wed Sep 12, 2012, 03:32 AM
DreamGypsy (2,240 posts)
2. A few religious paintings might need to be touched up ...
After reading the post and article I took my usual next step: Wikipedia for facultative parthenogenesis.
First of all I learned the origin of the word parthenogenesis:
The word parthenogenesis comes from the Greek παρθένος, parthenos, meaning "virgin", and γένεσις, genesis, meaning "birth".
Second, virgin birth doesn't seem to be all that rare:
Parthenogenesis is seen to occur naturally in aphids, Daphnia, rotifers, nematodes and some other invertebrates, as well as in many plants and certain lizards. Komodo dragons and the hammerhead- and blacktip sharks have recently been added to the list of vertebrates — along with several genera of fish, amphibians, and reptiles — that exhibit differing forms of asexual reproduction, including true parthenogenesis, gynogenesis, and hybridogenesis (an incomplete form of parthenogenesis).
Third, depending on the parthenogenetic mechanism, the resulting individuals may be female or male, haploid, diploid, or polypoid:
In apomictic parthenogenesis, the offspring are clones of the mother and hence are usually (except for aphids) female. In the case of aphids, parthenogenetically produced males and females are clones of their mother except that the males lack one of the X chromosomes (XO).
When meiosis is involved, the sex of the offspring will depend on the type of sex determination system and the type of apomixis. In species that use the XY sex-determination system, parthenogenetic offspring will have two X chromosomes and are female. In species that use the ZW sex-determination system the offspring genotype may be one of ZW (female), ZZ (male), or WW (non-viable in most species but a fertile, viable female in a few (e.g., boas)). ZW offspring are produced by endoreplication before meiosis or by central fusion. ZZ and WW offspring occur either by terminal fusion or by endomitosis in the egg cell.
In polyploid obligate parthenogens like the whiptail lizard, all the offspring are female.
And a result from stem cell research:
The process of parthenogenesis can only produce females in humans.
So, if that most famous of all virgin births was a case of parthenogenisis, the babe would probably not have developed a beard after puberty.
However, in the section on mammalian parthenogenesis, the Wikipedia article reports:
Induced parthenogenesis in mice and monkeys often results in abnormal development. This is because mammals have imprinted genetic regions, where either the maternal or the paternal chromosome is inactivated in the offspring in order for development to proceed normally. A mammal created by parthenogenesis would have double doses of maternally imprinted genes and lack paternally imprinted genes, leading to developmental abnormalities. ... (In swine) Parthenotes can be surgically transferred to a recipient oviduct for further development, but will succumb by developmental failure after ~30 days of gestation.
So, parthenogenesis in humans is most likely inconsistent with life. Not surprising.
Whew. Don't get out the paint. Let the mystery be.