Algae with three sexes that mate in pairs identified in Japanese river (2021) | Hacker News Reader

Algae with three sexes that mate in pairs identified in Japanese river (2021)

sciencedaily.com

148 pointsanimal_spirits52 comments

Schizophyllum commune, known as the splitgill mushroom, has over 23,000 sexes. Two individuals are sexually compatible based on genes at two sites in their genome. If a pair has matching genes at either location, the pair is not sexually compatible.

Is there any possibility that humans could be similar given that not every couple can have children naturally?

There is a massive difference. With that kind of mushroom one can expect that any random pair is very likely to match up. With humans you have tad less of 50% chance of being able to make kids with any random otherwise fertile human.

Err, that is an uncharitable reading of GP imo. If you pair males and females (rather than just "humans") then the anology holds quite well no?

I think the topic is getting a bit muddled here. Are we talking about couples who can't have children because one or the other is infertile/sterile, or couples who could have children with someone else but not one another?

I'm not familiar with this latter scenario. A man being sterile is nothing like this algae's situation, as it has nothing to do with "pairing," he's simply unable to produce children with anyone.

How often is the inability to have children naturally dependent on direct compatibility, rather than the ability of one or both partners to have children at all, regardless of partner?

This is an interesting idea because it seems like it could be true and we've just never noticed. I'm not sure how you'd go about designing a study but I guess it would be easy to find volunteers.

> but I guess it would be easy to find volunteers.

I don't know, in my experience people are sure picky about procreating with random strangers (and the ethical concerns regarding the output of the study are... significant).

From people I've known undergoing fertility treatments (and from my own limited research), the issue is frequently traceable to a specific cause in one or both partners (although it appears to be unexplained in about 20% of couples who seek treatment, which would be a small subset of the general population).

Maybe a HyperLogLog (HLL) data structure would be useful to store all of those options.

It’s only 23,000 options, a plaintext file would work fine. Computers are fast.

So just adding more about it, it seems that the sex consists of 4 parts, A-alpha, A-beta, B-alpha, B-beta. To be compatible it has to have differences in (A-alpha OR A-beta) AND (B-Alpha OR B-beta).

I can't help but think that this complex system has to have evolved to very precisely control inbreeding rates.

In plants, your genetic siblings are in many cases growing very physically close to you - especially if the seed dispersal mechanism isn't great.

That makes mechanisms to reduce inbreeding even more important.

And it's still one species? Wild.

Imagine the number of pronouns...

That brings up the question of what one means by "sex". As I understand it, sex is primarily about the kinds of gametes one produces - either large gametes (female) or small gametes (male). The genetic implementation of that is in some sense a secondary detail, since it varies between organisms. Reptiles, for instance, only have XX chromosomes and sex is determined by environment (or something like that).

I would expect that in this case the mushroom still only has two types of gametes, and hence only two sexes. There's just an added bit of complexity determining whether a particular pair of gametes can produce a new organism.

No, they're isogamous and have no sexes. They do have mating types.

Ah, that makes sense as well. But the idea of thousands of sexes seemed suspect to me.

These are not sexes but mating types. Schizophyllum is isogamous and has no sexes. An organism's sex is defined by anisogamy.

For a very different, but interesting, example, see these sparrows, which kind of have four sexes: https://www.nature.com/articles/539482a

That is not four sexes at all. That is a potential speciation event and "weird sex chromosomes." There is still a large gamete and a small gamete and no other type of sex cell involved. Two sexes.

It's actually pretty sad that this (non-peer reviewed, layperson-written) article got published as-is in Nature. Tetrahymena thermophila has no sexes; it is isogamous. Chromosome configurations are not sexes. But I guess the point of the article is the human interest story, not the subject of the title.

So those aren't a third sex, it's individuals with both male and female reproductive cells.

Sounds like a third sex

I think it depends on how you define sex, or perhaps even gender would be more accurate?

In any case, I think what's being proposed is there are still on 2 unique sexes.

- some of the species have one - some of the species have the other - some have the ability of both.

Technically, yes, that's still only two.

How do you define sex? Because what you just described sure sounds like a third sex to me.

Your description is premised on the assumption that there are only two sexes to begin with, and define the third sex in terms of the two sexes you assume to be the only ones that exist. Instead you could describe them as sexes A, B, and C where any of following pairings are valid for reproducing: A and B, A and C, B and C, or C and C.

Actually. No.

You need two differnt "widgets" to tango, not three.

Unless you say Sex A and Sex B together is a third sex Sex A+B. But that would only make sense if A+Bs were unique in the sense that they can only mate with other A+Bs. Then A+B would be a third sex. That's not the case, is it?

Put another way, sex is a property, not a class.

But they're calling it a third sex because it's due to "normal expression of the species' genes", not because of hermaphroditism.

It is a third (or fourth) phenotype, not a third sex. The abstract of the source article is careful to spell this out; the clickbait site introduced the error.

"Three sex phenotypes in a haploid algal species give insights into the evolutionary transition to a self‐compatible mating system." -- i.e. how might self-pollinating plants have developed?

Like in "the player of games" the third sex was both female and male.

Is that how it was? If my memory serves the third sex was effectively "female", in that you had:

- producer of small gamete (human male)

- producer of large gamete (half of human female)

- incubator of embryo (half of human female)

Are we defining sex by the type of gametes produced by an organism?

> they can produce normal male or female colonies when they reproduce sexually with other P. starrii colonies

There's also fungi with a fuck ton of genders, excuse the pun.

Schizophyllum commune, putting the "fun" in "fungi".

This article does not describe a species with three sexes. It describes a species with two sexes that can co-exist (or not) in the same individual organism.

It's somewhat unique because of the "(or not)" — most anisogamous species have either two phenotypes that produce one and only one of the gametes, or a single phenotype that produces both (like many flowering plants).

Still only two sexes, though—just more than two phenotypes.

"each sex can enter fertile pairings with 22,960 others"

Imagine its Tinder profile :)

I can't get past the mental visualisation of the gender drop-down list on the registration. Or the "seeking" list.

A list would only work if selection is limited. A better UI decision would either be a “sex cloud” akin to a word cloud, or the bubble UI that Apple Music uses to identify your preferred genres.

To be a success you'd need to create some kind of yubikey specifically for DNA sequences.

Hell I'd imagine you'd need something like that just to meet people at a bar.

In the late 90's I designed a dating website and we had about 5 axis to have categories for morphology, preferences, compatibility, etc. Sadly, I didn't stay long enough to see it deployed to production, and never actually used the application (Amigos Virtuais, at Universo Online, in Brazil). The PO and I had a lot of fun with all other personality dimensions that we had.

Tinder is not necessarily about "fertile pairings" though, but I guess humans (and some monkeys) are pretty unique in nature in that regard :)

It's almost entirely about secondary sex characteristics and those exist exclusively to find fertile mates. Gay people still look at their potential partners secondary sex characteristics when deciding to mate with them. It's sort of a distinction without a difference situation.

In using Tinder at all? Yeah, that's pretty much just humans.

Or Twitter pronouns.

When defining by which pairs can reproduce, or at least "connect corresponding mating organs", humans are also still limited to 2 sexes, pronoun discussion (in American English) acknowledges 2 sexes and decouples gender from that. A one to many relationship, instead of a one to one relationship.

(I've found in other English variants, consensus is evolving differently with non-binary genders equalling additional sexes, this can make things confusing online - like on Twitter - if you aren't noticing that maybe Commonwealth countries are forming this conversation differently)

> When defining by which pairs can reproduce, or at least "connect corresponding mating organs", humans are also still limited to 2 sexes

For ~98.3%, yes. About 1.7% [1] are... more difficult to answer that question for. For example, take a person with XX chromosomes but a penis and a person with XY chromosomes and a vagina. The "connect mating organs" step will work, but the pair will be infertile in almost all cases.

Even when one disregards social gender identity and purely focuses on "biological" attributes, nature has given humanity a lot of options - most people will fit into the "standard" model of hormones, chromosomes and the presence of naturally-grown genitalia, but a lot of people will not.

[1]: https://www.unfe.org/intersex-awareness/

> About 1.7% are ...

According to https://pubmed.ncbi.nlm.nih.gov/12476264/ it is more like 0.018 % than 1.7 %.

“As a user, I only want to search for users whom I can pair with. All incompatible users should be excluded by default”.

Now go and build it.

We detached this subthread from https://news.ycombinator.com/item?id=30625506.

Now imagine the list of pronouns they'd need to choose to create a Tinder profile...

Piers Anthony, Cluster series, Spicans.

Some people say fact is stranger than fiction, but art and life have such parallels.

I was just thinking about this series the other day and am pleasantly surprised to run across someone else who has read it.

Heh, I was just thinking about the Xanth and Cluster series and how I don't hear about them much these days. I devoured Piers Anthony's books in my teens.

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