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Bibliography TOPIC: OPERATIONAL SEX RATIO

Berglund A, 1994. The operational sex ratio influences choosiness in a pipefish. Behav Ecol 5: 254 -258 This study looked at male choosiness in pipefish. Males in male biased populations showed no preference between large and small females. However, in female biased environments males spent longer amounts of time with larger females, showing some effects of operational sex ratio on sexual selection in pipefish.

Fitze, P. S. and Le Galliard, J.-F. (2008), Operational sex ratio, sexual conflict and the intensity of sexual selection. Ecology Letters, 11: 432–439. doi: 10.1111/j.1461-0248.2008.01158.x Researchers determine that reproductive costs rather than operation sex ratios predict the intensity of sexual selection in lizards. The results of the study show a positive and significant correlation between number of mates and body size for both males and females, showing sexual selection for body size is increased a significant amount with for males in female biased populations and for females in male biased populations.

McNamara KB, Wedell N, Simmons LW. 2013 Experimental evolution reveals trade-offs between mating and immunity. Biol Lett 9: 20130262.http://dx.doi.org/10.1098/rsbl.2013.026 This article examines the effect of sex ratio on sexual selection on moths as well as effects of this selection on the immune system of the moths. Researchers found that in populations that are female biased that males have significantly lower immune function as a result of the male moths increased ability to make with more females.

Nandy, B., Chakraborty, P., Gupta, V., Ali, S. Z. and Prasad, N. G. (2013), SPERM COMPETITIVE ABILITY EVOLVES IN RESPONSE TO EXPERIMENTAL ALTERATION OF OPERATIONAL SEX RATIO. Evolution, 67: 2133–2141. doi: 10.1111/evo.12076 This article looks into sperm competition between males in populations of drosophila brought upon by effects in operational sex ratio. Effects of the male sperm was determined by experimental design using red eyed competitior males and observing progeny. Males grown in male dominant populations were found to have greater “sperm offence” and “sperm defense” when compared to males grown in a female biased population.

Székely, T., Weissing, F. J. and Komdeur, J. (2014), Adult sex ratio variation: implications for breeding system evolution. Journal of Evolutionary Biology, 27: 1500–1512. doi: 10.1111/jeb.12415 Talks in-depth about the differences and similarities between operational sex ratio and adult sex ratio. Researches also discuss the effects of operational sex ratio and adult sex ratio of the mating systems and paternity of lobsters fish and mice. Sex differences in adults is also discussed in terms of sexual based selections. And adult sex ratio is looked at for use in breeding systems.

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.

addition - Temperature can play a large part in OSR of a population. In many reptiles, sex determination is dependent on temperature of the environment during embryonic development. Consistently warm or cool environments can result in large biases in sex ratio of a population.