locus, in which case it is known as intralocus sexual conflict. Intralocus sexual conflict occurs because many phenotypic traits are determined by a common set of genes which are found and expressed in both male and female individuals. For example, phenotypic traits such as body size, diet, development time, longevity, and locomotory activity are typically positively genetically correlated between sexes. These traits have also been suggested to underlie intralocus sexual conflict because they may be subjected to antagonistic patterns of selection, in which elevated values of one trait result in enhanced fitness in one sex but decreased fitness in the other, generating a negative correlation for fitness between male and female individuals that express a particular trait. Development Bonduriansky and Chenowith proposed a four phase model for the development of intralocus sexual conflict, in which the first phase is stabilizing selection on a trait in both sexes. Intralocus conflict then originates in the second phase when a change in physical or social conditions causes intense selection on that trait in males and/or females, and both sexes are displaced from their optimum. In the third phase, diverging selection continues on both sexes, but is attenuated. In the fourth phase, intralocus conflict is fully resolved and sexual dimorphism has occurred. Examples A good example of intralocus sexual conflict can be seen in humans, regarding the selection pressures on height that varies between sexes. In nature, a negative correlation between the height of a woman and her reproductive success has been seen, with selection favoring relatively shorter women. On the other hand, men of average height are preferred, and have higher reproductive success than men who are shorter or taller in nature. Studies have been able to produce evidence concluding that higher reproductive success is obtained by females in sibling pairs that were shorter in height, whereas reproductive success in sibling pairs of average height was much higher in males. These findings show that intralocus sexual conflict over a physical trait, such as height, can have an effect on Darwinian fitness in humans. Intralocus sexual conflict diminishes the benefits of sexual selection. Examples of intralocus sexual conflict can be seen all throughout nature. In humans, males and females who appear to be more masculine in their physical appearance for their sex report to have brothers that score a higher mate value relative to their sisters. Similarly, individuals who are of normal weight and