Talk:Operational sex ratio

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I would support merging into sex ratio; it's not like the article is ever going to be deleted as in becoming a red link. Does it have the potential to go beyond a stub? Richard001 (talk) 08:04, 22 October 2008 (UTC)

Agree, merge & redirect. Can't really imagine a strong argument against that. Pete.Hurd (talk) 15:30, 22 October 2008 (UTC)

I just wanted to make sure it was alright that I added the sentence on the theory of OSR. It was somewhat explained, but not exactly stated and considering it's what most research is based on and what recent research is trying to confirm, I felt it should be added. Didn't mean to make the edit as anonymous ( I thought I was logged in. whoops!). Also a heads up that I will be adding extensive information to this stub page in the near future, which I hope is also alright. Elisa lara (talk) 22:13, 9 October 2013 (UTC)

I'm about to add some extensive information to this article. mostly elaborating on biased OSR, factors that can change OSR, and factors that can be predicted by OSR. I'll possibly add a small section on what future research can still be done. Elisa lara (talk) 00:09, 18 October 2013 (UTC)

Suggested Changes

1. I think it would be appropriate to include evolutionary effects of OSR in a male biased population OSR. An example being that it has been found that in the organism Drosophila when present in male biased populations selection can occur for higher sperm competitive ability.

2. Similary, addition of evolutionary effect of OSR in a female biased population would be helpful to understand its effects. example: sexual selection for body size in male lizards was 4.4 times greater in female biased populations as opposed to male biased populations.

3. I think including a small section on adult sex ratio could be beneficial in understanding the difference between OSR and Adult Sex Ratio (ASR) OSR being the ratio of sexually active adults and ASR simply being the sex ratio of adults in the population.

Possible addition

Operational Sex Ratio can cause rapid evolution of some species due to the intensity of sexual selection it can create. A study done on Plodia interpunctella, a species of moth, found that phenoloxidase levels or (PO) (an enzyme linked to immune system function) in males, in a female biased environment were significantly lower than the PO levels of males found in Male biased environments or equal OSR environments as seen in figure 1. It was found that males living in a female biased environment mated three times more than males living in a male biased environment. While male biased environments can increase sperm competition causing the moths to have more sperm per ejaculate when compared to female biased environment, there was no change in phenoloxidase activity. However, in female biased populations where mating events happen three times more often male sperm expenditure was overall greater. This selective pressure caused evolutionary tradeoffs between immunity and mating to result. Flies in the presence of a female biased over generations evolved to have increased mating ability at the apparent expense of phenoloxidase activity. This study is an excellent example of how Operational Sex Ratio can have evolutionary effect a species evolutionary. (McNamara). Operational Sex Ratio is also a large factor in contributing to evolution of sperm competition in many species such as Drosophila. In a study done by Dr. Bodhisatta, sperm competition was observed to evolve in male flies living in male biased populations within 60 generations. This study showed that males living in a male biased populations evolved significantly stronger ability for their sperm to fertilize female eggs if they were the first to mate with said female. This ability called “sperm defense” was shown to be increased in males living in male biased populations and to be reduced in males living in female biased populations. This is presumably due to the fact that in female biased populations need for sperm defense is not a selective pressure due to the fact that there are a significant amount of females compared to males and less overall pressure to find mates for males (Nandy B.).

Rachwal.1 (talk) 01:26, 18 November 2014 (UTC)

Rachwal.1 (talk) 21:01, 30 September 2014 (UTC)