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how does female cannibalizing the male fit into darwin evolution theory ? that evolution should make reproducing less efficient, either the male is dead before

how does female cannibalizing the male fit into darwin evolution theory ? that evolution should make reproducing less efficient, either the male is dead before he finish reproducing with the female or at least, he is not able to reproduce with other females. Yet it seems to be working just fine with other species of octopuses where the male get eaten.

amelius 2y ago
Maybe the female can use the proteins for her offspring, and there are more offspring to offset the lost male.
RajT88 2y ago
Presumably the female acquires calories with which to grow her brood. "Unable to reproduce with other females" is probably relevant. The relative size of different genders has a lot to do with if a species is polygamous or monogamous. Larger males the former and larger females the latter.
- HarHarVeryFunny 2y ago
  Yes, although the fact that the male has evolved this venomous defense seems to indicate that benefit of maintaining diversity in the gene pool (maybe good genes even, if he had to compete to mate) might outweigh the benefit of being a quick snack for a post-coital hungry female.
sebzim4500 2y ago
The effect of natural selection is that the genes that propagate most are the ones that maximize the probability of that gene appearing future generations. There is no direct evolutionary pressure for an individual to behave in ways that benefit the species in general.
- lolinder 2y ago
  Yes, because there is no concept of "species" in nature, species is an arbitrary grouping we humans apply to the individuals and genetic lines that are actually involved in natural selection. The female's genes are most likely to get passed down many generations if the males she mates with have genes that enable her male children to survive long enough to reproduce. Once a species gets into a state where females make a habit of eating the males during copulation, it can't readily evolve out of that state, because a female that is less aggressive will mate with males who can't succeed at mating with other females, leading to that line dying out. Sexual cannibalism is a local maximum. So if at any point in the past there were evolutionary pressure that made cannibalism beneficial to the genes, we would expect to see it stick around until there's sufficient pressure against cannibalism to allow selection away from that local maximum.
  - Falimonda 2y ago
    What local maxima might humans be stuck in?
    - delfinom 2y ago
      Emotional and social drives that keep us from letting genetic defects to die out of the gene pool.
      - whattheheckheck 2y ago
        Have you considered the technology developed to save/help due to that drive could be and probably is, a net benefit to science? And I am fairly certain that evolution requires much longer time scales than the 10k years of civilization humans have existed in?
  - somenameforme 2y ago
    > "a female that is less aggressive will mate with males who can't succeed at mating with other females" That premise is the fundamental point that your argument hinges on and I see no reason to just assume it would be true, and can create plenty of plausible arguments (that I think are fairly self evident) for why it would be untrue.
svnt 2y ago
Eggs are way more resource-intensive than sperm. The female octopus will take care of the eggs and protect them, and then die after they hatch. Both parents are all-in, probably because some less malleable trait or characteristic, whether environmental or hereditary, requires them to be so.
- bell-cot 2y ago
  > Both parents are all-in... THIS. The life expectancy of an octopus is extremely low - https://en.wikipedia.org/wiki/Octopus#Lifespan https://en.wikipedia.org/wiki/Octopus#Lifespan - and they're all-in on the "extreme number of offspring, microscopic survival rate" strategy. So for a male - it's a fairly reasonable tactic to end up as a big, nourishing meal for the female that will go all-in on producing the eggs of your decedents.
andirk 2y ago
With preying mantis and black widow it seemed, as their names suggest, very common for the female to eat the male after being boinked. However, it turns out that in the lab setting with a small closed environment, probably lots of lights and weird sounds, the female was freaked out, which led to her getting the first meal she could find, that being the male. In the wild, it does happen but as a last resort if food is scarce. The orb spider figured out a hack: he ejects his member in to her after sex which keeps inseminating her from that point forward. Sure he dies, but he reproduces from beyond the grave!
- deleted 2y ago
  [deleted]
- Imustaskforhelp 2y ago
  Isn't the orb spider really inefficient? What if one specific mutation of orb spider is really nice but he was killed and its "member" is in a single female orb spider limiting the greatness of a good mutation I suppose which can feel counter to evolution to me I suppose.
  - thaumasiotes 2y ago
    > What if one specific mutation of orb spider is really nice but he was killed and its "member" is in a single female orb spider limiting the greatness of a good mutation That's a very soft limit; a spider lays dozens (hundreds?) of eggs after mating once. Mortality is extremely high, so there's tons of room for "really nice" mutations to spread quickly.
- paulddraper 2y ago
  Cannibalism is legitimate in the wild. However, as you suggest it’s not necessarily a mating thing. If the animal is hungry and there is a food source (and no reason to do anything else), the pro-survival option is chosen.
- thaumasiotes 2y ago
  > With preying mantis and black widow it seemed, as their names suggest The praying mantis is named after its characteristic posture while standing around. There is no preying mantis.
paulddraper 2y ago
Game theory. The female benefits from a meal. The male benefits via procreation. A different choice by either party would be suboptimal.
sircastor 2y ago
It's important to say that evolution isn't versioned, and what we're observing isn't finished. We may be looking at an evolutionary dead-end. Which is to say that if eating the male is an evolutionary development, it might a poor one. There is no logic to evolution. No decisions are being made. Evolution is reactive, and the surviving lineages may only be responding effectively to some of the external forces. Evolution doesn't happen at a species level, it happens at the individual level and has downstream effects on the species. We're seeing evolution in action. Tragically, we (individually) won't be around long enough to observe the changes in another 100 or 200 or 1000 generations.
saghm 2y ago
> either the male is dead before he finish reproducing with the female or at least, he is not able to reproduce with other females In addition to the sibling comment's caveats, it's worth mentioning that the latter might actually be an advantage? If the male is able to continue reproducing with an unbounded number of females, and the females are limited by how often they can lay eggs (or how quickly they can after copulation), a mutation that causes females to prevent males from reproducing with other females could potentially drown out the ability of females without those mutations to reproduce (e.g. if those females were able to copulate with most males first, they'd be the only ones to produce offspring, and there could even be other adaptions or mutations that aid them in the "first to copulate" race).
littlestymaar 2y ago
Go read The selfish gene, these things are being discussed in depth in the chapter “The war between sexes”.
deleted 2y ago
[deleted]

amelius 2y ago

Maybe the female can use the proteins for her offspring, and there are more offspring to offset the lost male.

RajT88 2y ago

Presumably the female acquires calories with which to grow her brood. "Unable to reproduce with other females" is probably relevant. The relative size of different genders has a lot to do with if a species is polygamous or monogamous. Larger males the former and larger females the latter.

HarHarVeryFunny 2y ago
Yes, although the fact that the male has evolved this venomous defense seems to indicate that benefit of maintaining diversity in the gene pool (maybe good genes even, if he had to compete to mate) might outweigh the benefit of being a quick snack for a post-coital hungry female.

sebzim4500 2y ago

The effect of natural selection is that the genes that propagate most are the ones that maximize the probability of that gene appearing future generations. There is no direct evolutionary pressure for an individual to behave in ways that benefit the species in general.

lolinder 2y ago
Yes, because there is no concept of "species" in nature, species is an arbitrary grouping we humans apply to the individuals and genetic lines that are actually involved in natural selection. The female's genes are most likely to get passed down many generations if the males she mates with have genes that enable her male children to survive long enough to reproduce. Once a species gets into a state where females make a habit of eating the males during copulation, it can't readily evolve out of that state, because a female that is less aggressive will mate with males who can't succeed at mating with other females, leading to that line dying out. Sexual cannibalism is a local maximum. So if at any point in the past there were evolutionary pressure that made cannibalism beneficial to the genes, we would expect to see it stick around until there's sufficient pressure against cannibalism to allow selection away from that local maximum.
- Falimonda 2y ago
  What local maxima might humans be stuck in?
  - delfinom 2y ago
    Emotional and social drives that keep us from letting genetic defects to die out of the gene pool.
    - whattheheckheck 2y ago
      Have you considered the technology developed to save/help due to that drive could be and probably is, a net benefit to science? And I am fairly certain that evolution requires much longer time scales than the 10k years of civilization humans have existed in?
- somenameforme 2y ago
  > "a female that is less aggressive will mate with males who can't succeed at mating with other females" That premise is the fundamental point that your argument hinges on and I see no reason to just assume it would be true, and can create plenty of plausible arguments (that I think are fairly self evident) for why it would be untrue.

svnt 2y ago

Eggs are way more resource-intensive than sperm. The female octopus will take care of the eggs and protect them, and then die after they hatch. Both parents are all-in, probably because some less malleable trait or characteristic, whether environmental or hereditary, requires them to be so.

bell-cot 2y ago
> Both parents are all-in... THIS. The life expectancy of an octopus is extremely low - https://en.wikipedia.org/wiki/Octopus#Lifespan https://en.wikipedia.org/wiki/Octopus#Lifespan - and they're all-in on the "extreme number of offspring, microscopic survival rate" strategy. So for a male - it's a fairly reasonable tactic to end up as a big, nourishing meal for the female that will go all-in on producing the eggs of your decedents.

andirk 2y ago

With preying mantis and black widow it seemed, as their names suggest, very common for the female to eat the male after being boinked. However, it turns out that in the lab setting with a small closed environment, probably lots of lights and weird sounds, the female was freaked out, which led to her getting the first meal she could find, that being the male. In the wild, it does happen but as a last resort if food is scarce. The orb spider figured out a hack: he ejects his member in to her after sex which keeps inseminating her from that point forward. Sure he dies, but he reproduces from beyond the grave!

deleted 2y ago
[deleted]
Imustaskforhelp 2y ago
Isn't the orb spider really inefficient? What if one specific mutation of orb spider is really nice but he was killed and its "member" is in a single female orb spider limiting the greatness of a good mutation I suppose which can feel counter to evolution to me I suppose.
- thaumasiotes 2y ago
  > What if one specific mutation of orb spider is really nice but he was killed and its "member" is in a single female orb spider limiting the greatness of a good mutation That's a very soft limit; a spider lays dozens (hundreds?) of eggs after mating once. Mortality is extremely high, so there's tons of room for "really nice" mutations to spread quickly.
paulddraper 2y ago
Cannibalism is legitimate in the wild. However, as you suggest it’s not necessarily a mating thing. If the animal is hungry and there is a food source (and no reason to do anything else), the pro-survival option is chosen.
thaumasiotes 2y ago
> With preying mantis and black widow it seemed, as their names suggest The praying mantis is named after its characteristic posture while standing around. There is no preying mantis.

paulddraper 2y ago

Game theory. The female benefits from a meal. The male benefits via procreation. A different choice by either party would be suboptimal.

sircastor 2y ago

It's important to say that evolution isn't versioned, and what we're observing isn't finished. We may be looking at an evolutionary dead-end. Which is to say that if eating the male is an evolutionary development, it might a poor one. There is no logic to evolution. No decisions are being made. Evolution is reactive, and the surviving lineages may only be responding effectively to some of the external forces. Evolution doesn't happen at a species level, it happens at the individual level and has downstream effects on the species. We're seeing evolution in action. Tragically, we (individually) won't be around long enough to observe the changes in another 100 or 200 or 1000 generations.

saghm 2y ago

> either the male is dead before he finish reproducing with the female or at least, he is not able to reproduce with other females In addition to the sibling comment's caveats, it's worth mentioning that the latter might actually be an advantage? If the male is able to continue reproducing with an unbounded number of females, and the females are limited by how often they can lay eggs (or how quickly they can after copulation), a mutation that causes females to prevent males from reproducing with other females could potentially drown out the ability of females without those mutations to reproduce (e.g. if those females were able to copulate with most males first, they'd be the only ones to produce offspring, and there could even be other adaptions or mutations that aid them in the "first to copulate" race).

littlestymaar 2y ago

Go read The selfish gene, these things are being discussed in depth in the chapter “The war between sexes”.

deleted 2y ago

[deleted]