Alternative reproductive phenotypes (ARPs), is a situation in which within one taxa males differ in traits associated with competition for females. An example may be Rhizoglyphus robini with two heritable morphs: armoured fighters and more female-like, benign scramblers. Morphs can coexist within one population and very often their proportion is stable. Here we were wondering whether polymorphism in the genes underlying ARPs is maintained by balancing selection. If it true there should be a stable proportion of morphs which will be restored by selection after perturbation (artificial change of proportion). We tested this using experimental evolution in two types of environment: simple or spatially complex. We found that in both types of environment, the proportion of fighters came back to narrow range of 0.70-0.83 (similar to proportion reported by literature), although the rate of convergence was slower in the complex environment. Our results thus demonstrate balancing selection acting on polymorphism(s) underlying ARPs.