Experimental evolution with an insect model reveals that male homosexual behaviour occurs due to inaccurate mate choice

The existence of widespread male same-sex sexual behaviour (SSB) is puzzling: why does evolution allow costly homosexual activity to exist, when reproductive fitness is primarily achieved through heterosexual matings? Here, we used experimental evolution to understand why SSB occurs in the flour beetle Tribolium castaneum. By varying the adult operational sex ratio across 82–106 generations, we created divergent evolutionary regimes that...