Why This Fungus Has Over 20,000 Sexes

By Nathaniel Scharping | November 6, 2017 3:23 pm
Every Schizophyllum commune you see is likely a new gender. (Credit: wasanajai/Shutterstock)

Every Schizophyllum commune you see is likely a new sex. (Credit: wasanajai/Shutterstock)

Gender isn’t really a fungal construct.

Where we have two traditionally recognized genders, male and female, some species of fungi can have thousands of sexes. It sounds confusing, but it’s actually helpful — with so many variations, the fungi can mate with nearly every individual of their species they meet. It must make for a wild singles night.

Sexy Fun Guys

One species of fungi, Schizophyllum commune, really shines when it comes to gender diversity. The white, fan-shaped mushroom has more than 23,000 different sexual identities, a result of widespread differentiation in the genetic locations that govern its sexual behavior. For humans, and all animals, really, this would never fly, because we’ve evolved a very specific method of reproduction that involves specialized sexual organs to do the mating with and sex cells to carry the genetic information.

Fungi, by contrast, keep it casual. To mate, all a fungus has to do is bump up against another member of its species and let their cells fuse together. S. commune uses a special kind of structure called a clamp connection to do this, and it allows them to exchange their cell’s nuclei, along with the genetic information inside. This keeps reproduction simple and means that a potentially huge number of sexes is possible — other fungi species have dozens or more, though S. commune is certainly an outlier.

It’s Not What You Think

The “sexes” don’t really involve physical differences either, as we might think of when the word “sex” comes to mind. The variations are all in the genome, at two separate loci, or locations, each of which has two alleles, or alternate forms. The loci are called A and B and the alleles are termed “alpha” and “beta.” That makes four possible sexes, but there’s another twist. Every A-alpha/beta and B-alpha/beta can have many different variants, called specificities. It amounts to more than 339 specificities for A and 64 for B. Putting those two together yields thousands of possible unique sexes.

The fungus can mate with any specificity as long as it’s different somewhere on both A and B. So, two prospective mates could both have the same A-beta and B-alpha, but have different A-alphas and B-betas and they’d be fine to hook up. If they shared A-alpha and A-beta, though, their pheromones wouldn’t be compatible, meaning that they couldn’t carry out the reproductive process. That leaves a ton of options for mating, though, and essentially means that anyone a fungus meets is fair game for sexy time.

It also really helps spread genetic diversity around, because there are so many options. Think about that next time you’re looking for a date.

 

(h/t Popular Science)

CATEGORIZED UNDER: Living World, top posts
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  • Adrian Mróz

    Isn’t gender the wrong word. Shouldn’t it be over 23,000 sexes? We have certainly more than two recognized genders.

    • Le Fox

      Intersex isn’t a separate gender, and neither is a hermaphrodite.

      Fungi still have to have a binary mating system. the 23,000 sexes claim is a bit erroneous, as mating involves the exchange of genes.

    • Rick Gutleber

      Gender is a grammatical term. Its use to describe sexes is always wrong.

      • http://picknit.com/ Isaac Rabinovitch

        And yet the word gets used that way in academic paper, legal documents, etc., etc. Can people please stop assuming that the usage that they themselves are comfortable with is the only “correct” one?

    • mithras

      Whether you like it or not, we have two traditionally recognized genders, as the article states.

  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    I laud the fungus for its diversity as long as it pays for its own healthcare.
    I am not sure being somewhere between the Clintons and Harvey Weinstein would make me happy to be a mammal. Consider the ambiguities of child support.

    • Erik Bosma

      How about their reality shows?

      • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

        Schizo Commune! One had beast stream it or blue noses will be running.

  • Erik Bosma

    Imagine how the members of that fungus would identify themselves: LGBZFTTRWQPQQB…. etc, etc

  • Hard Little Machine

    I blame white male cisheteropatrirarchy.

    • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

      Add oppressive historic White Protestant European patriarchal factualism versus Situated Knowers in Standpoint Theory.

    • http://picknit.com/ Isaac Rabinovitch

      Which is, appropriately enough, getting kinda mouldy.

  • BestEver

    Next time you are looking for a date think about spreading genetic diversity around. After you get consent, but before divulging you are HIV positive.

    • Le Fox

      You can get away with it in California.

  • DutchS

    This strikes me as like saying humans have a million sexes because males and females share somewhat different genes with each other.

    • William Holz

      That wouldn’t be a correct interpretation.

      Imagine instead you could reproduce with anyone other than your siblings and occasional random people you meet.

      It’s a different approach to genetic diversity, and it appears to be working for the little guys, they’re pretty dominant on this planet.

  • Le Fox

    The original paper this article and claim is based on comes from 1966 and was written by J.R. Raper. It does not say there are 23,000 sexes per se, but argues that there are a multitude of sexual mating types. The way this fungus breeds still requires genes from two different entities.

  • Andre Pires

    This is a good ‘click bait’ title. In this article, the definition of ‘sex’ is referred in the technical literature as ‘mating type’. Fungi of the same mating type cannot mate with each other. However, if there are 20,000 different mating types around, they have plenty of options. This type of mating system makes them highly promiscuous. The original paper is “Raper, J.R., Krongelb, G.S., and Baxter, M.G. (1958). The Number and Distribution of Incompatibility Factors in Schizophyllum. The American Naturalist 92, 221-232”.

    I still struggle in how to define organisms that have males, females and hermaphrodites. In some nematodes, hermaphrodites can reproduce by self-fertilization and also by crossing with males. Males and females are definitely 2 different sexes. What about hermaphrodites? Can they be defined as the third sex? When crossing with males, hermaphrodites function as females because the sperm of the male fertilize the oocytes of the hermaphrodite. Since the sperm of the hermaphrodite cannot be transferred to females, these nematode hermaphrodites do not function as males when crossing with different individuals. However, since they self-fertilize, they function as male and female at the same time. What name to give them? Are hermaphrodites a different sex? Or are they a different gender? Or maybe they need a different name?

  • DerpDerpDerp

    Only three exist. That’s it. Sad that you guys had to go in to sci-fi to pull views.

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