Charles Darwin defined sexual selection as “variance in the number of mates”. The purpose of sexual selection is to refine secondary sexual characteristics, which are the morphological differences between the two sexes. On the other hand, primary sexual characteristics are the differences between the reproductive genital systems of the two sexes. Sexual selection, instead of adapting the individual to the environment, like natural selection, improves the traits involved in mate acquisition. Sexual conflict, on the other hand, occurs when males and females have different reproductive interests resulting from the drive for sexual reproduction. This is reinforced by promiscuity when males and females have different partners. (www1, www2, www4)Futuyma (1998) defines sexual selection as “selection that results from differences in mating success (number of mates giving birth to offspring)”. Sexual struggle can be divided into two categories. The first category is the fight between individuals of the same sex (generally males) to win against the rival by killing him or forcing him to retreat. In this category females remain passive. The second category is the fight between individuals of the same sex but this time it occurs to attract individuals of the opposite sex. There are also some theories about the existence of sexually selected traits. Intrasexual selection exists, in which males aggressively compete with each other for access to females. It includes weapons such as horns, antlers, tusks, and spurs, which are examples of sexual dimorphism. Weapons are predominantly male characteristics and some possible explanations for their existence are: protection against predators, used for co...... middle of paper ......same sex as they compete for mates and also between the sexes how individuals choose their partners. Sexual conflict arises because strategies that maximize the fitness of one sex may reduce the fitness of the other. To summarize, sexual conflict can lead to sexually antagonistic coevolution, in which one sex develops a favorable trait, which is counteracted by a contrasting trait in the other sex. (www5, www6) Works Cited • http://www.zoology.ubc.ca/~otto/PopGen500/Discussion3/Overheads.htmlhttp://bio.research.ucsc.edu/~barrylab/classes/animal_behavior/SELECT. HTM#anchor460576: http://aarongoetz.netfirms.com/My%20Articles/SexualConflect-bookreview-atg.pdf • http://www.medicalnewstoday.com/articles/21967.phphttp://onlinelibrary.wiley.com/ doi/10.1002/9780470015902.a0003669.pub2/abstract• http://onlinelibrary.wiley.com/doi/10.1038/npg.els.0001718/abstract