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Thread: Vampire Crabs MAY be Parthenogenic!

  1. #17
    swords's Avatar
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    Yes, due to the invasiveness of certain crayfish we are not allowed to import any species of aquarium crayfish to my state. But they are still available, simply labeled as "freshwater lobsters" at all the aquarium shops...

    Obviously I have no plans to release these land crabs to the Minnesota wilds. They will only be going to fellow hobbyists who have asked to be placed on a waiting list for the babies. Only a few people have them here at the moment so my goal with having them is a captive breeding program, not just to have it. I originally bought 5 extra pairs from a reptile breeder/author who did a one-time import for himself of this new red species after he had been having had success with breeding the Geosesarma bicolor (purple and yellow species). This red species does not behave in the same manner as the G. bicolor so things written about those "vampire crabs" are not exactly right for the reds but they are close. I have been meaning to do a write up for some time so the people who want Red babies from me can get their tanks setup and matured and know what to expect before I get ready to ship the first babies in spring/summer - provided I can catch the fast little buggers! LOL

  2. #18

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    Quote Originally Posted by amphirion View Post
    Yeah, i get the crayfish partho, but all those crayfish are genetically identical, and all female....in the case of the rattlesnake, that is something is different that i totally dont get: rattler born from a VIRGIN snake is male. and there's no fertilization whatsoever, so it's different from bees...
    While domesticated honeybees do not start laying eggs before mating, fertilisation is not required at all. Since queen bees mate once in their lifetime, old queens eventually deplete their sperm store and start laying drone eggs only. (This leads to the collapse of the colony.) "False queens" display similar behaviour. When a queen dies suddenly and no queen larvae are present, a worker bee may start laying haploid eggs, just like an old queen. In this case, the false queen is technically and biologically a virgin. All parthenogenetic eggs are haploid males, while all fertilised eggs are diploid females. Workers and queens are only phenotypically different.

    Parthenogenesis in snakes is very rare, as far as I know. Superficially, the process may resemble that of honeybees, i.e. only male offspring through virgin birth. The difference is quite subtle. What determines gender in honeybees is haploidity versus diploidity. This means that individuals with a single copy of their genome (haploids) are male, while individuals with two copies (diploids) are female. In snakes, what determines gender is the chromosomal W-Z system. This is very much like the X-Y system in humans, only reversed: males are homogametic, i.e. ZZ, while females are heterogametic, i.e. ZW. At least one copy of the chromosome Z is required for survival. So, why can virgin snakes only give birth to viable male offspring? Meiosis in females creates four haploid cells from a diploid somatic cell: three infertile polar bodies and one fertile egg cell. You may want to have a look at this chart to understand oogenesis:

    Oogenesis

    Since sex chromosomes are separated during the first meiotic division, both the egg cell and the secondary polar body will have the same sex chromosome. They are genetically identical, in fact, except for any homologous recombination that might have occurred earlier. (This recombination is the reason why virgin-born male snakes are not 100% genotypically identical to their mothers.) What happens afterwards is conjectural. We assume that the secondary polar body, which is genetically identical (again, except recombinated material) to the egg and in closest proximity, acts like a sperm and fertilises the egg cell, thus creating a diploid zygote which may or may not develop normally. Since both cells carry the same sex chromosome, the zygote will be either ZZ or WW. ZZ is a normal male, but WW is not a viable organism.

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    I hope my scientific explanation didn't kill the thread! Looking forward to hear more.

  4. #20
    swords's Avatar
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    Well I guess there wasn't really anything more to add until these little ones are sexable and we'll see what the M/F ratio is if they aren't just all female. So I'll probably post an update on this possible Parthenogenic brood next February! LOL

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