Why would males exist in species with hermaphrodites?

I'm designing a world with a humanoid race, which has two sexes, male which is analogue to human male, and hermaphrodite which is analogue to human women with additional male reproductive organs, like futanari from Japanese manga.

After reading this answer by John to the question Gender ratio in a three gender system:

Sex ratios are controlled more by mating strategy than anything else, even species with the same sex chromosomes can have vastly different sex ratios. So really it is controlled by how many partners each sex has at a time. if your species is monogamous, or serial monogamous like humans, then you actually can have a wide range becasue the normal 1:1 gets thrown for a loop when you have both sexes at the same time as an option. I suspect you will quickly see the hermaphrodite begin to dominate the gene pool since they can switch hit depending on circumstances.

Males are high risk but potentially high reward, like a lottery, less likely to find a mate but also capable of hitting the Genghis Khan jackpot. Females are a conservative but safer bet, they are almost guaranteed to reproduce but have an upper limit on on the number of offspring they can have. So if their ratio gets unbalanced the opposite sex has a big advantage so the people will have more of that sex until they reach equilibrium again. Too many males and males have even less of chance to find a mate so females get favored, if females dominate males have a much better chance of finding multiple partners so males get favored.

Hermaphrodite have both a sure thing and the chance of the jackpot. The only thing preventing hermaphrodite domination is if males or females (or both) are less willing to mate with hermaphrodites than the opposite sex.

So really it's entirely dependent on how hermaphrodites are viewed as possible mates. If they are just as desirable as the opposite sex soon all you have is hermaphrodites. basically the less males and females are willing to mate with hermaphrodites the closer to male/female domination you will see and the more willing they are the closer to hermaphrodite domination you will get.

It seems that males are unnecessary and that having hermaphrodites offspring is a winning strategy for parents.

Could there be any explanations why such a species still has males?

posted over 6 years ago

hozagi‭

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