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from the you-say-crayfish-I-say-crawfish dept.
No one knows exactly when the clones first appeared, but humans only became aware of them in the early 2000s.
It was a German aquarium owner who first brought it to scientists' attention. In 1995, he had acquired a bag of "Texas crayfish" from an American pet trader, only to find his tank inexplicably filling up with the creatures. They were all, it turns out, clones. Sometime, somewhere, the biological rule that making baby crayfish required a mama crayfish and papa crayfish was no longer inviolate. The eggs of the hobbyist's all-female crayfish did not need to be fertilized. They simply grew into copies of their "mother"—in a process known as parthenogenesis.
Crayfish specialists were astonished. No one had seen anything like it. But the proof was before their eyes and in 2003, scientists dubbed the creatures marbled crayfish, or Marmorkreb in German.
https://www.theatlantic.com/science/archive/2018/02/attack-of-the-crayfish-clones/552236/
(Score: 2) by c0lo on Tuesday February 06 2018, @05:55PM (5 children)
Unlike normal females, the eggs are fertile without the presence of a male.
So it should be beyond more than (beyond of) a normal female, especially with a triploid genome.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by insanumingenium on Tuesday February 06 2018, @06:19PM (3 children)
(Score: 2) by c0lo on Tuesday February 06 2018, @07:20PM (2 children)
Sexual reproduction with the need of a male sex to produce descendants. But...
... further reading shows that the above definition is too simplistic (so thanks for making me read further.
I suspect that you'll be pleased to hear that parthenogenesis doesn't necessary produce female only descendants [wikipedia.org] - so "the future is female" is... mmm... greatly exaggerated? (especially when a low genetic diversity means that species extinction due to an illness is almost a certitude on long terms)
I'm curious, so I'll be grateful for any detailed study about sexual reproduction in triploids that maintains the triplod trait as a species constant
The line of my thinking - chances are the offspring to show a dispersion between diploid and tetraploid on different chromosomes, with an average 50% of chromosomes in triplicate, 25% in pairs and 25% chromosomes in tetraploid state in the first generation (meiosis II produces haploids and diploids with equal frequency)
The chances of "all chromosomes in triplicate" is (1/2)N, where N is the number of chromosomes. To have a pure triiploid species using sexual reproduction exclusively would require:
1. any non-triploid chromosome in the set is a death warrant (otherwise you'll never see a pure triploid species)
2. a small number of chromosomes (and thus a non-infinitesimal chance of all-chromosome triploids) and/or a huge number of offspring so the (1/2)N chance still offer chances of some viable descendants. E.g. 20 chromosomes will result in a "all triploid" configuration with a chance of 1 in a million viability.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by insanumingenium on Tuesday February 06 2018, @08:22PM (1 child)
Let's see
polyploid - check
obligate parthogens - no males fo this species exist - check
You want a polyploid that breeds true, take one of my favorites The California Redwood [wikipedia.org], it is a hexaploid the reproduces sexually. If you want a triploid in particular, you are correct that it doesn't usually breed true, breeding is an integer process (usually, though some fungi are really weird), and three into two makes awkward math.
Also, in case I haven't beat this horse enough, and since you seem to like wikipedia as a source, please see here for the definition of female [wikipedia.org]
(Score: 2) by c0lo on Tuesday February 06 2018, @11:13PM
No, I wanted an example ofa pure triploid with sexual repro.
Examples of even-ploidy reproducing sexually are quite common in the plant world.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Interesting) by frojack on Tuesday February 06 2018, @06:55PM
Define fertile.
They only grow into clones, this sounds more akin to what Planarian flatworms do when they re-form clones from slivers 1/300th of their original size. To do this, planarians use stem cells, called cNeoblasts, that have the ability to become almost any cell type in the body. I'd speculate this is the same sort of stem-cell process, but instead of worm sections , the stem cells are in the eggs).
I don't think the concept of fertility applies here. The process is probably orthogonal to fertility in that it is entirely asexual.
No, you are mistaken. I've always had this sig.