Heritability of male secondary sexual traits in feral guppies in Japan

Secondary sexual traits of male guppies show remarkable geographic variatio n, and male guppies can flexibly change the conspicuousness of their sexual traits within a few generations when they are introduced into new habitats . We examined the degree of conspicuousness and heritabilities of male seco ndary sexual traits in a feral guppy population in Okinawa, a subtropical i sland of Japan. Male guppies in this population showed high variation of th eir sexual traits such as dorsal and caudal fin lengths and red-orange colo r spot patterns on their bodies. Offspring parent regressions revealed sign ificant heritabilities of male body size, dorsal and caudal fin lengths, an d the number and relative area of orange spots. Especially, the high herita bility of the relative orange spot area of sons compared to that of fathers suggests some Y chromosome-linked contribution of the trait. On the other hand, coloration (hue and saturation) of orange spots did not show signific ant inheritance, probably because most components of orange spot coloration may be condition-dependent traits. These results compared with previous wo rk in native guppy populations suggest female mate preferences based upon t hese male secondary sexual traits and low predation pressure in this popula tion.