Talk:Sperm competition

Untitled

I linked this article to Gryllus bimaculatus to provide an example. Emiliaromagna1 (talk) 22:35, 6 December 2015 (UTC)

Rewriting

The original article was utter bollocks. So I rewrote it. Dunc_Harris|☺ 14:25, 14 Jul 2004 (UTC)

I created the article with the evolutionary psychology of rape as my frame of mind. If larger ejaculate load in response to infidelity or suspicions of infedility is not to go under sperm competition, then where should it go? Mbac 15:22, 14 Jul 2004 (UTC)

First we need to establish the basic principles of sperm competition, which I think I have reasonably done by defining it and giving a bit of history. Thanks for making me write the article :) I'm coming at it from a evolutionary biology point of view of course, but a straight biological one rather than a anthropogenic one. If you can provide citation for that claim about heavier ejaculates, then that would be good. Dunc_Harris|☺ 19:28, 14 Jul 2004 (UTC)

"However, sperm are costly to produce" ... ??

Is there a reference for this? It doesnt sound plausible that manufacturing sperm would require more calories/energy than e.g. brushing one's teeth.

There is a references section in the article. Dunc|☺ 09:13, 13 Jun 2005 (UTC)

perhaps, but I can't find a citation justifying the above claim re costliness of sperm production. Sounds like a belabored rationale for a pet sociobiology theory.

Firstly, what's wrong with sociobiology? Sperm competition is an accepted paradigm that is over thirty years old and just because you might not like the implications of socibiology doesn't mean that they're not right and supported by the evidence. Dunc|☺ 09:41, 14 Jun 2005 (UTC)

OK Mr. Smartypants, explain how sociobiology dictates that sperm are biologically costly to the sperm-producing organism. Why should sperm be more costly to produce than e.g. blood cells or snot? My point being that the original statement in the article sounds like a belabored post-hoc rationale for a pet theory and should have a clear citation backing it up rather than some general non-specific references.

Don't be unnecessarily rude. The article explains the concepts and provides references. Unfortunately it is clear that you don't understand it, and have not read the references provided. Dunc|☺ 09:43, 17 Jun 2005 (UTC)

Ok, so you can't explain it, just say so. Don't be unnecessarily obtuse.

You were the one who started it by asking a stupid question. — Dunc|☺ 21:04, 23 January 2006 (UTC)

See section "Are sperm costly?" in Wedell et al (2002) Pound 28 Oct 2005

if sperm are in fact biologically costly, why is primate masturbation so rampant? the masturbators should have been bred out of existence by now.

We still need a citation for that fact, regardless of the number of references in this article. It is not the readers' responsibility to read through all the references to find the source of one fact. 70.23.22.82 21:58, 17 February 2007 (UTC)

Masturbation is perfectly compatible with evolutionary theory. The first explanation is that by masturbating an animal gain experience of having sex (psychological effect), and it keeps them in a state of alert, in terms of hormomes, and the fact that sperm have a sell by date anyway. They will masturbate less (if at all), when having regular sex, so is does not present a disadvantage during that time.

But it is not that sperm cost a lot, each individual costs very little, and sperm are cheap (an egg in contrast is expensive). The model requires that they cost something, because then in a promiscuous society, those who produce more get an advantage, and therefore those that produce more have an advantage. It is really very simple. — Dunc|☺ 21:04, 23 January 2006 (UTC)

I'm not sure exactly how costly sperm themselves are to produce, but in some insects the male ejaculate is something like 25% of their body weight (much of which is nutrition for the female). Now that certainly is costly. Richard001 06:55, 30 August 2007 (UTC)

Article Misses the Point

This article misses the point enunciated in the bookSperm Wars that not all sperm in the ejaculate are for inseminating the ovum, some are specialized to attack and impede sperm from other males, the corollary hypothesis being that gang rape eg in war has been a sgnificant contributor to human evolution.

Pajy 23:41, 26 July 2007 (UTC) Has any evidence ever been found for haploid expression in the sperm - sperm differences are not the original way in which sperm competition was defined - the point of the raffle analogy is surely that the tickets are similar. Differentiations of sperm do occur but are they genetic? It seems also that the explanatory arsenal available in the sperm competition theory explanations of peri-reproductive behaviour are if anything too extensive. All of the cases are covered. A male amy mate guard if he does not sperm load, plug, or fight or invoking disease and making the best of a bad job if none of these are engaged in what is the falsification case for the theory? Species exist where large sperm, few in number does therefore that adaptations exist to benefit reproductive edge translate as anything other than a truism and not require the underpinning of sperm competition theory distinct from evolutionary theory? The adaptations used to ensure fertilisation are so diverse and numerous; sometimes having little to do with the explanation of why male gametes are small and numerous (a tautology in any case as this is also a definition of male in biological terms - which is determined by a diversity of genetic causes)and not relying on this fact that the theory must need evaluating from this standpoint is it really distinct or sufficient?

Huh. This article is on my watchlist but I don't think I've read it before. (Probably the product of drunken midnight editing.) Anyway - I agree the article misses the point, though I can't be arsed to parse the paragraph above. But: a significant portion of sperm competition probably occurs as haploids - that is, sperm from a single male competing with their own brothers to reach the egg. Most of selection is in testes-expressed genes, so either (a) there's a lot of "gang rape" going on in evolutionary history, a suggestion that is typical of sociobiology's inanity, or (b) what i said above, which is much more plausible. I'll hunt up some references. Graft | talk 16:36, 3 April 2008 (UTC)

References need updating

References should be inside <ref>{{cite journal | author = | year = etc.}}</ref>tags rather than (Smith, 1977) then under the references heading there should be a {{reflist}} template. Jack (talk) 21:18, 4 April 2008 (UTC)

I would not doubt the project of Sociobiology - that a biological basis for behaviour and that there is an evolutionary basis for biology is not at stake to my mind. Just the Sperm Competition theory which would benefit from some of the countering arguments - for instance what I was trying to get at before in the expression of haploid strategies in the sperm (in Sperm Wars style) - what happens in the case of a man who produces sperm exhibiting mutually incompatible strategies - his own ejaculate would be in competition with itself - surely a strong selection pressure against haploid expression? —Preceding unsigned comment added by 81.104.166.133 (talk) 13:03, 9 August 2008 (UTC)

I want to know who thought of this theory

Is this theory new? —Preceding unsigned comment added by 118.169.99.32 (talk) 04:29, 5 April 2009 (UTC)

I believe the seminal paper is Parker (1970) – reference 1 in the current article. Qwfp (talk) 11:24, 6 February 2010 (UTC)

Bizarre

The header of this article sounds a little un-encyclopedic to me.

"Sperm competition is often compared to having tickets in a raffle; a male has a better chance of winning (i.e. fathering offspring) the more tickets he has (i.e. the more sperm he inseminates a female with). However, sperm are not free to produce [2], and as such males are predicted to produce sperm of a size and number that maximizes their success in sperm competition. By making many sperm, males can buy more "raffle tickets", and it is thought that selection for numerous sperm has contributed greatly to the evolution of anisogamy (because of the energetic trade-off between sperm size and number)."

This example is a good way of explaining the concepts, but breaks away from the focus of the article. I propose it be moved to it's own section called "Example" or something of that nature. This'll help clean it up so that it sounds more like an encyclopedia and less like a text book. Warthomp (talk) 06:37, 10 December 2010 (UTC)

Needs a complete re-write

This article is very odd. It needs to be completely re-written, or at least thoroughly revised.

First, the article talks about sperm adaptations, which seems straightforward enough, but then it talks about changed social behaviors ("harem-keeping", etc). So is sperm competition a biological, evolutionary concept concerning sperm, or a social one engaged in by males (and not just sperm), or both? This needs to be made very clear.

Second, to who or what does this concept apply, exactly? Does it apply to humans, other animals, or both? The relevant references need to be kept separate as well. For example, in the second paragraph, a reference to "Competition and its Evolutionary Consequences in the Insects" is made in a paragraph that speaks generally to behaviors in animals (and humans?). This is confusing, to say the least. --Fang Aili ^talk 23:46, 2 May 2011 (UTC)

Penis adaptations against sperm competition

This article hasn't mentioned anything about the evolved adaptions that both animal and human penises have to defend against sperm competition. For example, Gallup et al. (2003) found that phalluses without a coronal ridge displaced significantly less semen than phalluses that did have a coronal ridge. This therefore suggests that the coronal ridge is an evolved adaptation in humans to defend against sperm competition. Other animals also have evolved adaptions designed to displace the semen of other males, for example, male lake ducks have spiny penises with bristled tips. 2.30.150.25 (talk) 19:35, 29 January 2016 (UTC)

References

Offensive behavior traits

I added a bit to 'offensive adaptations' making clear that offensive behavior is facilitated by certain traits which are called armaments. I also alluded to the possibility that these traits serve to communicate social status, which sometimes results in non-violent resolutions of competition. Please feel free to contact me in case there are any objections! Roja123 (talk) 22:39, 10 February 2016 (UTC)

Strange sentence

In the second paragraph of "Mate Choice" we find this sentence: "An adequate diet consisting of increased amounts of diet and sometimes more specific ratio in certain species will optimize sperm number and fertility." Clearly this makes no sense and needs changing.Wordwright (talk) 17:45, 9 May 2016 (UTC)

How does a male know he's won?

There is no point to competing if you can't tell that you've won; how does any male know that a female's offspring is his?Wordwright (talk) 17:47, 9 May 2016 (UTC)