Technology: Worm Species Only Produces Males For Their Sperm - PressFrom - US
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TechnologyWorm Species Only Produces Males For Their Sperm

23:26  14 march  2019
23:26  14 march  2019 Source:   newsweek.com

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Worms that fertilize themselves lost one-fourth of their genome, including genes that make sperm In fact, no known selfing Caenorhabditis species have mss genes. And mss genes are only active in The selfing species of worms may have lost the mss genes because having competitive male sperm

For starters, only female members of the species exhibit that signature emerald colouration. It's a reasonable guess, but spoon worms slurp down only tiny edible particles. The blobs you see are By contracting their muscles in a wave-like pattern, the invertebrates send their internal fluid towards

Worm Species Only Produces Males For Their Sperm© Marie Delattre Embryos of Mesorhabditis belari as they are fertilized. There is a species of worm in which the females only produce males for their sperm, scientists have discovered. The reproductive strategy, thought to be unique to nematodes, ensures no genetic material from males ever enters the female population and keeps the population stable.

Researchers led by Marie Delattre, from the l'ENS de Lyon in France, were building on observations taken by biologist Victor Nigon 70 years earlier. He had noticed that one species of nematode—Mesorhabditis belari—had a very low population of males and that female embryos were clones of their mothers.

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a species of round worm which evolved from having males and females to having self-fertilizing hermaphrodites. As I understand how ordinary hermaphrodite reproduction works, two individuals contribute genes to an offspring, which preserves the benefits of sexual reproduction.

These two species are very closely related, so they can actually produce viable and fertile offspring. Under normal circumstances, having sperm that can migrate quickly up the reproductive tract is advantageous for males who compete with other males for the best spot for their sperm inside the

Delattre and her team have now carried out genetic analysis of the nematodes to find out exactly what is going on. Their findings, published in the journal Science, revealed their bizarre reproduction strategy.

“[I was] very surprised,” she said. “It is very unusual to find a species were males are not needed for their genes. Often, females have interest in producing males mainly because they spread their genes—and so the genes of their mothers—and through crosses allow genetic mixing, leading to healthy genomes.”

The team found that females need the male sperm to activate their eggs—but most of the time no genetic material is passed on, meaning all the females were clones. However, nine percent of the time, a male was produced. When genetic material from a male was used after the egg was fertilized, a male was always produced. These males could only reproduce with their female siblings and could only pass on their genetic material to sons—meaning their DNA would never enter the female gene pool.

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When a female worm mates with multiple males , the sperm jostle each other, competing for access to the eggs. Female worms ’ bodies must be able There is evidence for this theory. In the current study, three species of hermaphrodite worms —which produce their own sperm and fertilize their own

Researchers have discovered an unusual species of worm that has evolved ways to 'stray from the The researcher and colleagues previously found that the sperm - producing cells in the males of the According to Shakes, the species has only been seen twice in the wild: once in Connecticut, and

Worm Species Only Produces Males For Their Sperm© Marie DELATTRE/LBMC/CNRS Photo library The figure of nine percent, they say, was analyzed using game theory—a mathematical model often used in social sciences. Researchers found the nematode system allowed the species to maintain a stable population.

How such an unusual reproductive system evolved is now being investigated. “One hypothesis we have is that the ancestral species, which was a sexual species (that we know), maybe had a strong fertilization towards Y bearing sperm…but it is bad for a species to have too many males, so maybe this system emerged as an anti-drive system: Lets get rid of the male DNA, so that we have more females,” Delattre said.

But why keep males around at all? Delattre says that if certain mutations arise, eventually these nematodes might become an all-female species. “It is clear that if a mutation emerges in these population that would allow females to develop without the males, the mutation will invade the population and these males would disappear,” she said. “But we think that if they keep this reproductive system it is because there is no mutation that allows this.”

The team plans to look at the genome of the nematodes and evolution scenarios that could have led to the system. Delattre also said that it might be found elsewhere among species thought to be asexual. "[It was] only because we could follow their reproduction in the lab that we discovered this reproductive system," she said. "Knowning that this reproductive strategy exists, many more species could be re-analyzed, and some may show the same feature. I am convinced that this is not a nematode specific system."

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