Oogenesis & Asexual Reproduction...

stamenflicker

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stamenflicker
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Maybe I was just dreaming about virgin births since it is the season, but I seem to recall reading an article about 6 or 7 years ago regarding asexual reproduction involving oogenesis. Do species do this? If so, isn't genetic variablity cut way down? And if this has happened in a species, wouldn't the offspring have to be female, or asexual?

Probably a dumb question, but I can't remember what I read or where. Needing a biology whiz to step in and set me straight.

Thanks,

Flick
 
Aphids and water fleas reproduce asexually (parthogenesis) and the offspring are all female. Some invertebrates (such as rotifers) fish and lizards are parthenogenetic too,
 
Not a biology whiz- but I got into stick insects a couple of years ago, not in a contortionist way you understand, and I was flabbergasted to learn that my girls, as I call them (yes I know, sad really) can reproduce on their own quite happily. I`ve got about a thousand stick insect eggs ready to hatch next year by the way, if anyone wants any- plese....
I did have one male stick hatch, poor guy, and he strolled around like the cock of the walk for about 4 months until he noticed all the big ladies wanted nothing to do with him, and died.
There`s a lesson there somewhere...............
As far as genetic variability is concerned, I suppose a stick insect is pretty much a stick insect, and they do look EXACTLY like sticks. Where does one go from there?
Anyone want any eggs?
 
There are some strains of turkeys which reproduce parthenogenicly but not sure the technical type of reproduction they do but no males involved so I assume it involves oogenesis. There are a number of species which need no males but there have been suspected parthenogenesis in numerous other species including humans.
Yes it cuts down on genetic variability and if the species are only female then it can only reproduce this way which really limits genetic variability. Some species have several methods of sexual reproduction and some use both sexual and asexual reproduction, some are hermaphroditic and fertilize themselves if they don't find a partner. There are numerous variations in reproduction cycles of various species of this world.
 
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Some species of salamanders do this, too. There are other species that need sperm, but not to fertilize the eggs; they just need the sperm to cause the eggs to gestate. I can look up more for you tomorrow if you care to know.
 
Well, the advantage (rapid reproduction, no wait time to find mates) outweighs the disadvantage (reduced variablity, smaller pool of changes from which to draw under duress) - until the species is under stress. Under these circumstances, females can start giving birth to males, and some variablity is re-introduced, as variability within a population is a more advantageous trait in a shifting environment, while rapid reproduction is an advantage in times of stability.
 
In at least some asexually reproducing oligochaetes, this genetic rigidness is overcome by alternating between sexual and asexual forms. Generally, the worms stay asexual, reproducing for example by architomy, during favourable or stable conditions, and therefore quickly spread. When conditions deteriorate, or the environment becomes unstable, they switch to sexual reproduction, and then - often - die.
This cycle can be as short as a year in some species, with asexual reproduction throughout summer and autumn, and sexual reproduction kicking in when it gets colder. In some (all?) cases, the worms die after having reproduced sexually and deposited their offspring in cocoons.
See, for example, L. C. Armendáriz, Hydrobiologia 438: 217-226, 2000.

Further some fishes (and I believe there are some very large ones outside Madagascar who belong in this group) reproduce asexually but sperm-dependantly through gynogenesis. Sperm from a closely related species is needed to stimulate embryogenesis, but does not contribute genetically to the offspring. Naturally, all individuals of these fishes are female.
Other fishes display hybridogenesis, but even though I understand all the words in its descriptiuon, I am not entirely sure how it works.
See, for example, M. J. Alves, M. M. Coelho, and M. J. Collares-Pereira, Genetica 111: 375-385, 2001. This paper contains a description of hybridogenesis which I do not fully understand. It's there, though.
 
Whiptail lizards are another good example.

And I totally want stick-insect eggs. I wish I'd had them when I turned in my bug collection this semester... ;)
 
Dagny, PM me with how many you want and they are already on their way.
Don`t you need a licence for them in the US, though?
Oh I don`t care, just don`t let them escape ff sake.
 
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