Hermaphrodites wouldn’t work that well, because there is no clear distinction between the group that you are competing with and the group you are competing for, which would probably make any behavioral strategy unstable.
Why can’t hermaphrodites just compete on a single axis, with the winners of that competition being the ones who get to impregnate others?
(Perhaps the benefits of winning that competition are so large that some will specialise in winning rather than child-bearing, and thereby become males. But not if the competitive criteria are strongly correlated with hermaphrodism—e.g. the single axis being “how healthy your existing offspring are” or similar.)
But in your scenario the offspring has only one “successful” parent. The best outcome for hermaphrodites would be for the “winners” to mate with each other, but then it might be unstable to switch between mating and competing behaviour between the same two creatures.
Because it is probably hard to isolate the applications for each behaviour from each other. “Compete with A and mate with B as much as you can” is much easier to encode than “Compete with everyone, but then maybe at some point switch to mating with however you are fighting (but be careful that they don’t take advantage of it)”. You get the prisoner’s dilemma at the very minimum.
PS If you think about it, even in humans, who do have sexual differentiation and are capable of very complex behaviour, those behaviours are not perfectly isolated, and external aggressiveness often leaks into the family. For me it is almost out of the question that such careful delineation could exist among primitive hermaphrodites.
Why can’t hermaphrodites just compete on a single axis, with the winners of that competition being the ones who get to impregnate others?
(Perhaps the benefits of winning that competition are so large that some will specialise in winning rather than child-bearing, and thereby become males. But not if the competitive criteria are strongly correlated with hermaphrodism—e.g. the single axis being “how healthy your existing offspring are” or similar.)
But in your scenario the offspring has only one “successful” parent. The best outcome for hermaphrodites would be for the “winners” to mate with each other, but then it might be unstable to switch between mating and competing behaviour between the same two creatures.
Hmm, I guess I don’t really see why that’d be unstable?
Because it is probably hard to isolate the applications for each behaviour from each other. “Compete with A and mate with B as much as you can” is much easier to encode than “Compete with everyone, but then maybe at some point switch to mating with however you are fighting (but be careful that they don’t take advantage of it)”. You get the prisoner’s dilemma at the very minimum.
PS If you think about it, even in humans, who do have sexual differentiation and are capable of very complex behaviour, those behaviours are not perfectly isolated, and external aggressiveness often leaks into the family. For me it is almost out of the question that such careful delineation could exist among primitive hermaphrodites.