I am looking for a good answer to this question. I think clues of why females usually control paternity are in the energy investment in gamete size and its link with types of female fertilization. I do not know the processes or mechanisms promoting and maintaining such asymmetry and why males may control paternity in some species even with external fertilization, for instance, in fishes. In addition, why did not evolve a male internal fertilization? Any thoughts or literature suggestions about this subject are welcome. Thank you in advance.
Because there are more genes on the extra x female chromosome compared to y
Hello Rafael; Female investment in reproduction nearly always exceeds that of males. Gamete size, incubation, nest construction, parenting are all female-related costs that are not borne by males. As a result, the cost of reproductive failure is asymmetrically borne by females and so selection for "prudent" behavior is applied more forcefully on females. Of course there are some exceptions...species in which males engage in these costly behaviors. Jacanas, mouth-breeding cichlid fishes, pair-bonded species and the like. Best regards, Jim Des Lauriers
Thank you for the answers. The fact that female and male reproductive investment is generally empirically assessed does not provide a mechanism for the origin of this asymmetry. Why does female investment in reproduction nearly always exceeds that of males? I am looking for causal relationships between beeing a female (a morph that invest proportionally more energy in gamete production than males) and controlling parentage (fertilization). If you can suggest literature on this subject, it will be helpful.
Hello Raphael; The potential lifetime fecundity of whichever parental type (mom) produces the larger gametes is less than the other parental type (dad). Mate choice errors by moms are more costly than they are for dads. Thus, selection is predicted to favor "honest signals" by dads and highly discriminating moms. Interactions like that devolve into positive feedback loops. So to respond to your last point directly…
Any mom that can detect genetically superior dads by any trait will have a greater lifetime fecundity. The positive feedback starts and that’s about all you need.
I haven't followed this literature for some years and so can't offer a modern citation but I did encounter this paper that might help.
DeviStuart-Fox 2005. Deception and the origin of honest signals
https://doi.org/10.1016/j.tree.2005.08.004
Regards, Jim Des Lauriers
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