Miyatake Takahisa, Matsumoto Akira, Matsuyama Takashi, Ueda Hiroki R, Toyosato Tetsuya, Tanimura Teiichi
Laboratory of Animal Population Ecology, Faculty of Agriculture, Okayama University, Tsushima-naka 1-1-1, Okayama 700-8530, Japan.
Proc Biol Sci. 2002 Dec 7;269(1508):2467-72. doi: 10.1098/rspb.2002.2152.
Clock genes that pleiotropically control circadian rhythm and the time of mating may cause allochronic reproductive isolation in the melon fly Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae). Flies with a shorter circadian period (ca. 22 h of locomotor activity rhythm) mated 5 h earlier in the day than those with a longer circadian period (ca. 30 h). Mate-choice tests demonstrated significant pre-mating isolation between populations with short and long circadian periods. Pre-mating isolation did not occur when the mating time was synchronized between the two populations by photoperiodic controls, indicating that reproductive isolation is due to variations in the time of mating and not any unidentified ethological difference between the two populations. We cloned the period (per) gene of B. cucurbitae that is homologous to the per gene in Drosophila. The relative level of per mRNA in the melon fly exhibited a robust daily fluctuation under light : dark conditions. The fluctuation of per expression under dark : dark conditions is closely correlated to the locomotor rhythm in B. cucurbitae. These results suggest that clock genes can cause reproductive isolation via the pleiotropic effect as a change of mating time.
多效性控制昼夜节律和交配时间的生物钟基因可能导致瓜实蝇（Bactrocera cucurbitae (Coquillett)，双翅目：实蝇科）出现异时生殖隔离。昼夜周期较短（运动活动节律约22小时）的果蝇比昼夜周期较长（约30小时）的果蝇在一天中早5小时交配。择偶测试表明，昼夜周期短和长的种群之间存在显著的交配前隔离。当通过光周期控制使两个种群的交配时间同步时，交配前隔离并未发生，这表明生殖隔离是由于交配时间的差异，而非两个种群之间任何未明确的行为学差异。我们克隆了瓜实蝇中与果蝇的per基因同源的周期（per）基因。在光暗条件下，瓜实蝇中per mRNA的相对水平呈现出强烈的每日波动。在暗暗条件下，per表达的波动与瓜实蝇的运动节律密切相关。这些结果表明，生物钟基因可通过作为交配时间变化的多效性效应导致生殖隔离。
