Posted on 01/06/2025 5:56:01 AM PST by Red Badger
UC Davis graduate student Jeffrey Groh has discovered how walnut trees are able to produce flowers of different sexes at different times in the same season. The genetic mechanism is similar to sex determination in many animals. Pictured, Groh with a California black walnut tree on the UC Davis campus. Credit: Sasha Bakhter, College of Biological Sciences
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Biologists at UC Davis have uncovered a fascinating genetic mechanism in walnut trees, allowing them to alternate between male and female flowers each season—a trait stable for 40 million years.
This discovery not only sheds light on plant reproduction but also parallels mechanisms in human sex determination.
Unraveling the Sexuality of Walnut Trees
Biologists at the University of California, Davis, have uncovered the genetic basis behind the alternating sexes of walnut trees. Their research, published on January 3 in Science, identifies a mechanism that has remained stable in walnuts and their ancestors for an astonishing 40 million years. Intriguingly, this mechanism shares some similarities with sex-determination systems found in humans and other animals.
Flowering plants employ various strategies to avoid self-pollination. Some have physical structures that make self-pollination difficult, while others produce distinct “male” and “female” plants. Certain species, like walnut, hickory, and pecan trees, take a more dynamic approach by alternating male and female flowers within the same season. Remarkably, each walnut tree consistently follows one of two patterns: it either begins the season with male flowers (“male-first”) or with female flowers (“female-first”). This phenomenon was first noted by Charles Darwin in 1877. In the 1980s, Scott Gleeson, a graduate student at UC Davis, discovered that this flowering pattern is controlled by a single genetic locus.
Discovery of a Long-Standing Genetic Mechanism
“Walnuts and pecans have a temporal dimorphism where they alternate male and female flowering through the season,” said Jeff Groh, graduate student in population biology at UC Davis and first author on the paper. “It’s been known since the 1800s but hasn’t been understood at the molecular level before.”
This occurs in both domesticated walnuts and wild relatives, like Northern California black walnut. In wild species, the ratio of male-first to female-first trees is almost 1:1.
Groh and his doctoral advisor, Professor Graham Coop of the Department of Evolution and Ecology, made use of data from UC Davis’ walnut breeding program and also tracked flowering in native Northern California black walnut trees growing around the UC Davis campus. Assigning them to male-first or female-first groups, the researchers sequenced their genomes and identified sequences associated with the trait.
Evolutionary Insights: Mechanism Stability
In walnuts, they found two variants of a gene linked to female-first or male-first flowering. This DNA polymorphism appears in at least nine species of walnut and has been stable for almost 40 million years.
“It’s pretty atypical to maintain variation over such a long time,” Groh said. In this case, the two flowering types balance each other. If one flowering type becomes more common in the population than the other, the less common type gains a mating advantage, so it becomes more common. This pushes the system to a 50:50 equilibrium and maintains genetic variation.
Pecans, Groh found, also have a balanced genetic polymorphism determining flowering order, but in a different part of the genome to walnut. The pecan polymorphism appears to be older than in walnut, at over 50 million years.
How did walnuts and pecans, which are related, arrive at the same flowering mechanism through quite different genes?
It could be that the ancestors of walnuts and pecans converged on similar solutions as they evolved. But it’s also possible that this time-separated flowering system appeared even longer ago in this family, about 70 million years ago, but over time the exact genetic mechanisms to achieve it have changed.
Parallels to Animal Sex Determination
Intriguingly, this is similar to the way animal sex chromosomes work, with two structural variants (X and Y chromosomes in humans and other mammals) kept roughly in balance.
“There’s a clear parallel to a common mode of sex determination,” Groh said.
Reference:
“Ancient structural variants control sex-specific flowering time morphs in walnuts and hickories”
By Jeffrey S. Groh, Diane C. Vik, Matthew Davis, J. Grey Monroe, Kristian A. Stevens, Patrick J. Brown, Charles H. Langley and Graham Coop, 3 January 2025, Science.
DOI: 10.1126/science.ado5578
Additional authors on the paper are: Diane Vik, Matthew Davis, J. Grey Monroe, Kristian Stevens, Patrick Brown and Charles Langley, all at UC Davis. Funding was provided by grants from the U.S. Department of Agriculture, National Institutes of Health, National Science Foundation, the Davis Botanical Society and the American Society of Plant Taxonomists. This work made use of trees from the UC Davis Putah Creek Riparian Reserve; Gene Cripe of Turlock, Calif.; USDA Wolfskill Experimental Orchard; Sonoma Botanical Garden and the UC Botanical Garden at Berkeley.
How fashionable.
Tranny trees!
Notice something interesting...
The word gender is used in the headline.
But the word sex is used in the article.
That’s not an accident, I’ll bet...
Proof that Trannys are nuts!...........
These perverts are trying to get Walnut Tree Story Hour in your kids’ schools!!! Wake up, people!!!
Funny how he has his hand stuck into the crotch of the tree...
CORRECT.
Maybe he does more that just hug trees.............😏
I’m not sure the science dudes are trying “desperately” to find some evidence of nature performing gender reassignment as they are just saying - this is an awesome thing. This world is stunning in its beauty and variety.
Many plants in these times do not need gender anymore because mankind has been diddling with them for so long.
Er, that’s probably not exactly right - they still have genders but most plants can produce BOTH pollen and seeds all by themselves. (Don’t lecture me about growing pot, please - I already know.)
Also: Walnuts are delicious and nutritious and the wood is quite valuable.
When I saw this piece it made me think - however - of various weirdos I’ve chatted with online over the years who claimed that they were great magicians and that “a time is coming” when every human will be able to switch genders just by doing a little spell or whatever and I was like “LOL!! If you could do something like that by magic, why not just make yourself the emperor of the world and waste everyone you don’t like and stop worrying about something so insignificant!” (Sometimes I wonder if maybe I’m too hung up on being able to get rid of some people just by thinking about it....... OH WELL LOVE ME AS I AM!!! I WASN’T TALKING ABOUT YOU ANYWAY!)
So then I would get a scolding about how it was “everyone’s” sort of like JOB to make sure that if someone wants to change from a man into a woman (and back again, and then back again after that! like this one dude I met once) then we should do everything possible to help him. (It’s mostly guys that seem interested in this - I’ve never met a woman who talked about wanting to be a man, except for me when I was a kid.) I could tell a lot of these guys were just having like violent fantasies about being able to go into the women’s locker room and wreak havoc, right? “Wait until she finds out I’m NOT REALLY A GIRL! HA HA HA!!” “Bruh, I’m way ahead of you, I’ve got like THREE ACCOUNTS on this lesbo dating site!!! The hot lesbos are falling all over me!”
Moving on: I would listen to this lecture and then point out that having two genders in one body is like a disease and very undesirable and that people who are “born that way” are essentially disabled - I would also point out that parthenogenesis (some very simple life forms can indeed change from male to female and vice versa, like this walnut tree and some protozoa, fish, reptiles, etc) is not desirable, really, either, because it’s usually a reaction to some sort of environmental stress. “Oh, no, all the males couldn’t stop fighting with each other and now they’re all DEAD or incapacitated! What shall we do, my reptilian sisters!” “Some of us must change into males!” *cries of dismay*
I would say, “So, you’re fantasizing about the day that you will be as versatile as an amoeba!” and again point out that if you could do that with magic, you could just as easily obtain whatever the heck you wanted to s3x you up and go for it. It’s like using magic to put on your boots. JUST PUT THE DAMN BOOTS ON, ALREADY, AND GET GOING.
You probably know more now about “nature’s gender reassignments” than you want to! Have a wonderful day! xoxo
LOL!!!
>>>>(Don’t lecture me about growing pot, please - I already know.)<<<<
😉................................
Well....humans don’t have that mechanism. Next attempt at trans-speciation coming soon.
Might as well think you’re like a walnut if you are some kind of nut anyway.
When I saw this piece it made me think - however - of various weirdos
Tough times is the only cure for what ails us.
Ya know, it was those wonderful religious guys that discovered all this in the monastery, too. They were like, “Wow, this plant is a male! And THIS one is the same species but it’s a FEMALE!! WOW!!!” and Nob was like “Yes, you have learned one of Nature’s secrets!” and they performed experiments, and came to know more about agriculture than even royalty - and then people would accuse them of being sorcerers and so on.
People are always like “Religious people are SO STUPID because they don’t believe in evolution!” and it was the spiritual life in fact that gave us many, many valuable scientific discoveries.
“It’s pretty atypical to maintain variation over such a long time,” Groh said. In this case, the two flowering types balance each other. If one flowering type becomes more common in the population than the other, the less common type gains a mating advantage, so it becomes more common. This pushes the system to a 50:50 equilibrium and maintains genetic variation.
Every flower is one or the other. They do not change from one to the other.
“Tough times is the only cure for what ails us.”
Excellent quote! :D
Yeah I always think that: The human race has WAYYYYYY too much time on its hands lately.
IIRC, Mendel was a monk..........
Que up the biology of seahorses.......
If you show me a human that organically drops its penis for a vagina and then the vagina for the penis on some sort of natural cycle I’ll change my position that humans are not gender fluid.
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