Hermaphroditic hook up
I hope this clarifies it for you, if not please expand as to why, I am on here because I want to help people understand biology properly!Well fair enough about my external fertilizers comment.
To me true hermaphroditism should be very common (I realize it isn't) in species that don't need two parents to raise offspring, but do benefit from some (as in one parent's) parental care.
) and therefore it is not costly be a hermaphrodite.
I don't see your logic there, the cost is not necessarily to do with the cost of bearing child, producing & maintaining the gonads and gametes is also a costly process. This is not just on a morphological level but also physiological: in non-hermaphroditic species the sexes have very different, and often, conflicting gene expression and hormone production patterns.
Their densities are actually pretty high, so I'd wager they encounter each other frequently, so I'm not sure where that leaves them in terms of pressures for hermaphroditism.
Your point on the physiologic/hormonal issues of maintaining the systems is one I haven't previously considered.
I suppose the main thing I keep coming back to is the overwhelming disadvantage gender has in terms of potential to create offspring. ) species essentially act as little more than sperm donors, thus half the individuals have effectively zero fitness.