Female European green lizards (Lacerta viridis) prefer males with high ultraviolet throat reflectance

The role of ultraviolet (UV) signals in intraspecific communication has been identified in a number of vertebrate taxa. In lizards, the signalling role of UV has only been shown in male-male competition and male mate choice. Here, we investigated whether male UV colour can be a basis of female association preference in European green lizards (Lacerta viridis), a species where males develop blue nuptial throat colouration with high UV reflectance. We experimentally manipulated the UV colour of male pairs, where the members of the pair did not differ significantly in body length, body weight, head size, throat UV chroma and brightness or throat blue chroma and brightness measured prior to colour manipulation. By providing these pairs of males to females (only visual stimuli could be perceived by the females), we assessed the role of UV in female association preference irrespective of other potentially important visual traits. We found that unmated but receptive females preferred males of higher UV reflectance. Our results show for the first time that UV colour can be an important male signal in female preference in reptiles.