To elaborate a bit: when I read the description, it sounds like a person could make the same claim about humanity: "there are billions of sexes: John, Jane, Tim, Judy, Juan, Maria, etc etc"

How is this different? Or equivalently, what makes a "sex" a "sex" if it's just variability within the sex chromosome, but every individual is able to create progeny with 25% (?) of other individuals.

To me, that sounds like 4 sexes.

Here is the sparrow with four sexes: https://www.nature.com/news/the-sparrow-with-four-sexes-1.21...

Conversely, what we think of sex (the genitalia and dimorphism identification) may not even be defined specifically by genes sets, but by epigenetic/environmental responses.

Even though alligators have DNA sets that are swapped, they are largely physically sexed by temperature: https://en.wikipedia.org/wiki/Temperature-dependent_sex_dete...

It even has an advantage, as females without mates can sometimes spontaneously reproduce and have offspring that are both male and female: https://en.wikipedia.org/wiki/Parthenogenesis_in_squamata

I haven't read the article yet (looks like it's been DOSed by traffic from Hacker News?), but your criterion would be met in a population of 201 entities (numbered from 0 to 200) where each entity X can procreate with entities in the range [X-25 ... x+25] (mod 201, of course). That would arguably yield 201 distinct sexes, where each individual is sexually compatible with 25% of the population.

Instead of the range [X-25 ... X+25], assign to each sex a random one of the 200-choose-50 (4.6 * 10^47) possible groups of partners sexes with size 50.

It would be impossible to completely describe the set of sexual compatibilities without simply enumerating them, and therefore necessary to treat the sexes as a set of discrete entities.

I think that if each individual was randomly compatible with some subset of the population, we don't have 200 sexes, we have one sex and a 25% fertility rate.

http://botit.botany.wisc.edu/toms_fungi/feb2000.html

Also, there's this database with more pretty pictures and some distilled information:

http://www.mykoweb.com/CAF/species/Schizophyllum_commune.htm...

I hadn't realize how unique some of the fungal genetic systems were!

See Power, Sex, Suicide: Mitochondria and the Meaning of Life by Nick Lane.

https://www.youtube.com/watch?v=mPqWstVnRjQ

https://news.ycombinator.com/newsguidelines.html

People are here to discuss intellectually interesting things. Please let us eat our dinner.

How?

I come here for signal, it's one of the few places I know that still has a high signal/noise ratio. It's decreasing to be sure, but it'd be nice to keep it as high as possible for as long as possible.

Do you have an example?

"Perfect execution, great, great job." "That is brilliant!" "Interesting -- great idea! I'll have to think about the right way to implement that."