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I am designing an alien species of organism (not necessarily intelligent, in fact, probably not). My current settings are these:

The female is very large (bigger than cattle, smaller than elephants), have strong, pointed mouthparts for skewering prey or enemies and are capable of sudden bursts of speed. The males can fly, and are around the size of vultures or other large birds. They also have somewhat dexterous claws for gathering edible vegetables or processing meat.

The dynamic of the sexes is so: one adult female is followed by numerous males (perhaps 5 or 8). The males try to do the female favours, such as scouting for prey or gathering food for the female (both sexes are omnivorous, but prefer meat when it is available). As a reward, the female will become more intimate with a contributing male, and when sufficiently intimate, will mate with it.

I want to know if this system will be evolutionarily stable, as in whether or not some new system will take its place spontaneously as time goes on. For example, will more docile and sex-prone females become more successful than their more demanding counterparts, and hence push the latter out of the gene pool? Or perhaps some kind of sexual selection, similar to those that caused the appearance of peacock tails and the like, cause more "charismatic" male to be selected over diligently contributing males and hence destroy the system?

(I am also leaving out some details like what method of reproduction the organism uses (i.e. egg-laying versus live-birth) in case these variables can be set to stablize/disrupt the system)

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    $\begingroup$ Why is this even a question when we have bees and ants? Also really weird title, slightly miss leading. $\endgroup$ – Necessity Mar 12 '17 at 20:46
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    $\begingroup$ Bees and ant queens are served by females. Spiders do it the way proposed here, with little males bringing gifts / helping out. Not weird at all. As regards which way evolution pushes things, anything can happen. It depends on the fitness conferred by each strategy. $\endgroup$ – Willk Mar 12 '17 at 20:55
  • $\begingroup$ There are many examples where the males compete for female choice. If that's not yes enough for you, you should refer to specific real examples in your post and explain how your situation is different from real life. $\endgroup$ – JDługosz Mar 12 '17 at 21:58
  • $\begingroup$ I think this is either “unclear what you're asking” or trivially “yes” as answered by a short comment. $\endgroup$ – JDługosz Mar 12 '17 at 21:59
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    $\begingroup$ @Albert Mascians although I do not know of any Terrestrial animal with such large degrees of size difference due to sexual dimorphism it is not unknown in marine organisms. Ammonite fossils have been known to have females in some species 50 as large as the male of the species, some modern fish also show a large ratio. $\endgroup$ – Sarriesfan Mar 13 '17 at 16:29
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Sure, this all seems quite feasible. The mobility of the males means that the 2nd fittest can go looking for other females elsewhere. Therefore the gene pool diversifies and positive genes are spread around the world.

As for "peacock syndrome", if the male is primarily responsible for hunting, and they don't feed females who shun them, then the best hunters will succeed. Females who choose "flashy" males will die of starvation. Keep in mind though, this assumes getting food is hard enough that only fit males can do it well. If flashy males or females can gather adequate food you get peacock syndrome.

Finally, the females will probably be focused on defending the young, hence the spikes. They also have a huge incentive to be picky with their mates as they have lots of options available, and a bad choice means less food for them and the young. Therefore females need to be picky with mates and tough with predators, though once they've found a suitable mate they of course have an incentive to "put out", as it were.

I'd advise egg laying for this setup, as it means the female has a huge incentive to guard the nest, and therefor relies on the male to gather food. This would avoid peacock syndrome. And, if there are predators it would explain her decenses. Maybe the nests are somewhat inaccessible and that's why the males need to fly, to get in and out?

Edit: It's been pointed out that the females described in the OP did the hunting too. The above still applies though, just swap "hunting" for "scouting" in the list of male duties. Also, if the female is hunting, then eggs are a bad call, as the nest would be left undefended.

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  • $\begingroup$ From what the OP has written the males are not primarily the hunters, they act more like honey guide birds in Africa, pointing the female to prey items. It's the female that has pointed mouth parts and speed to actually kill the prey, then the males use their claws to butcher the body and aslo gather fruits etc. The female needs to be mobile to hunt for prey. $\endgroup$ – Sarriesfan Mar 12 '17 at 22:34
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There is no problem with this idea. Insects have been doing this sort of thing for a very long time. Males often give females nuptial gifts, and the quality of the gift is used to determine success. This is the abstract from one paper. This article and the articles that it cites will provide a wealth of possible scenarios.

Edible and seminal gifts that male arthropods transfer to their mates range from important material donations to items that provide little direct benefit. Recent reviews and research have emphasized the negative effect of gifts on female fitness, suggesting that male donations reduce the female's re-mating rate below her optimum or even that nuptial feeding is a net detriment to her fitness.

However, comparative, experimental, and natural history evidence reveal that most edible gifts of prey or glandular products provide direct benefits to females. Gifts clearly supply nutrients when females compete for them or increase mating rates when food from other sources is limited. I point out the difficulties in determining that female re-mating rates are sub-optimal and suggest several alternative hypotheses for the apparently low female mating rates in some gift-giving species. With regard to seminal contributions (absorbed from the ejaculate), I discuss how to separate hormonal (potentially manipulative) and material-benefit effects of male secretions on females.

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