Male-Male Competition - Background

Male-Male Competition can lead to extravagant male characters and sexual size dimorphism. Typically, males will compete for territory (in which body size or ornament characteristics will determine their ability to compete) and females will choose males based on the territory they possess. Males that are able to maintain larger territories of good quality will tend to acquire more mates and will therefore be more represented in the next generation. It is important, however, that differences in the ability to compete are genetically determined (heritable). Likewise, female preference for males/territories must also have heritable variation. Females choose territories that will maximize their reproductive output. Territory quality is often correlated with size per female.

In general, the more limited the territories are in number and quality, the stronger the selection for extravagant male characters and sexual size dimorphism. The degree of territory heterogeneity (both size and quality) can also affect the strength of sexual selection: the more heterogeneous, the stronger the selection. The reason for this is that female choice is more important if differences exist in their reproductive output.