Worms with three sexes discovered in Mono Lake

The paper has nothing to do with their sex but rather about their resistance to arsenic.<p>Nematodes often exhibit hermaphroditism, which isn’t exactly a third sex since hermaphrodites have both male and female gonads they still have binary sexual reproduction just with themselves and when reproducing with a male or a female sexually they would act as a female or a male respectively during reproduction.<p>As far as sexual reproduction goes this isn’t 3 sexes that require each other to reproduce or 3 distinct sexes that can reproduce with each other individually.

Not a biologist, but there&#x27;s nothing that novel about 3 sexes as such. Some fungi have thousands of sexes[1] for example. The way I heard it explained is from an evolutionary point of view there is selection pressure towards either 2 or very large numbers of sexes.<p>Very large numbers of sexes means it&#x27;s very likely that when 2 individuals meet they can sexually reproduce (whereas if you have only 2 sexes half the time they cannot). Say there are 100 sex types of a species it might well be that 80% of random couples could sexually reproduce together because there are far more compatible combinations.<p>On the other hand, evolutionary pressure towards 2 sex types comes from specialisation. It&#x27;s very helpful for the gamete to either be large and full of food for the developing embryo or to be small and fast to win the race to fertilize. Once the process of specialisation starts, the largest &quot;foodie&quot; gamete and smallest &quot;fast&quot; gamete tend to beat out all the others so you end up with 2 sexes one of which produces eggs and the other sperm.<p>[1] <a href="https:&#x2F;&#x2F;earthsky.org&#x2F;earth&#x2F;fungus-sexes-chromosomes-thousands" rel="nofollow">https:&#x2F;&#x2F;earthsky.org&#x2F;earth&#x2F;fungus-sexes-chromosomes-thousand...</a>

Paper: <a href="https:&#x2F;&#x2F;www.cell.com&#x2F;current-biology&#x2F;fulltext&#x2F;S0960-9822(19)31040-1" rel="nofollow">https:&#x2F;&#x2F;www.cell.com&#x2F;current-biology&#x2F;fulltext&#x2F;S0960-9822(19)...</a><p>Spoiler alert about the three sex:<p>&gt; <i>Auanema sp. shares features, such as possessing three sexes: hermaphrodite, male, and female (Figures S3H–S3Q), with its closest relatives, A. rhodensis and A. freiburgensis [12].</i><p>It doesn&#x27;t seam to be so unusual for nematodes <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Nematode#Reproduction" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Nematode#Reproduction</a>

&quot;and carries its young inside its body like a kangaroo&quot;<p>is fascinating for works.

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