Ecological Genetic Study of clock gene which can cause speciation

以瓜实蝇为模式种，解释了时钟基因多向性控制生活史和行为特征导致生殖隔离的机制。瓜蝇一天交配一次，时间是黄昏。被选为生活史特征的种群在白天的交配时间表现出相关的反应。例如，选择较快(较慢)发育的苍蝇种群有较早(较晚)的交配时间。昼夜节律控制着交配的时间。短发育期品系的昼夜节律周期约为22h，长发育期品系的昼夜节律周期约为31h。所选品系间杂交数据表明，发育期由多基因控制，而昼夜节律可能由单基因控制。这些结果表明时钟基因多向性地控制着发育和…。在瓜蝇中有更多的绝期。生殖隔离通常作为适应不同环境或生境的间接(多效性)结果而演变。例如，时间上或季节上错开的生态位可以选择具有不同发育特征的生物体。这些发育差异可能会不经意间通过各种方式造成生殖隔离，包括交配活动模式的变化。通过配偶选择测试，选定的发育期种群之间的交配时间差异转化为显著的合子前隔离。如果种群间的交配时间相差超过1h，则隔离指数显著高于零。这些发现表明，预先分离可以通过时钟基因的多效性效应来建立。在许多例子中，繁殖时机的差异阻止了种群之间的基因流动，例如海洋生物的产卵时间、被子植物的开花时间和昆虫的交配时间。在这样的生物体中，如果昼夜节律和生殖特征之间存在遗传相关性，对生活史特征的各种不同选择往往会通过时钟基因加速生殖隔离的进化。自然种群可能会通过漂移、直接的繁殖时间自然选择或作为遗传相关性的副产品而在繁殖时间上发生分化。无论如何，时钟基因是生殖隔离的关键。我们还分析了短、长发育期品系的周期基因和倍增基因的氨基酸序列，即时钟基因。短品系和长品系在倍增时间上存在点氨基酸差异，这种差异可能与南瓜实蝇交配时间的差异有关。为了研究这一点，我们需要鉴定果蝇黑腹变种系统，这是一个双重时间的零突变。较少

The mechanism by which a clock gene pleiotropically controlling life history and behavioral traits causes reproductive isolation is explained using a model species, the melon fly, Bactrocera cucurbitae (Coquillett) (Diptera : Tephritidae). Melon flies mate once a day, at dusk. The population selected for life history traits exhibits correlated responses in the time of mating during the day. For example, the fly populations selected for faster (slower) development have an earlier (later) time of mating. A circathan rhythm controls the time of mating. The circadian periods in constant darkness were about 22h in lines selected for a short developmental period and about 31 h in lines selected for a long developmental period. The data on crosses between the selected lines indicated that the developmental period is controlled by a polygene, whereas the circadian period may be controlled by a single clock gene. These results suggest a clock gene pleiotropically controls developmental and circ … More adian periods in the melon fly. Reproductive isolation may often evolve as an indirect (pleiotropic) consequence of adaptation to different environments or habitats. For example, niches that are temporally or seasonally offset can select organisms with different developmental characteristics. These development differences can inadvertently cause reproductive isolation by a variety of means including shifts in mating activity patterns. The difference in time of mating between populations selected for developmental period translated into significant prezygotic isolation, as measured by mate choice tests. If the mating time between populations differed more than 1 h, the isolation index was significantly higher than zero. These findings indicate that premating isolation can be established by a pleiotropic effect of a clock gene. There are many examples in which the difference in timing of reproduction prevents gene flow between populations, such as the egg spawning time in marine organisms, the flowering time in angiosperms, and the time of mating in insects. In, such, organisms ; if genetic correlations between circadian rhythm and reproductive traits exist, multifarious divergent selection for life history traits would often accelerate the evolution of reproductive isolation through clock genes. Natural populations may diverge in reproduction time through drift, direct natural selection for time of reproduction, or as a by-product effect of genetic correlations. In any case, clock genes are keys in reproductive isolation. We also analyzed sequence of amino-acid of period and doubletime genes, so called as clock genes, in short and long developmental period lines. The difference in a point amino-acid difference in doubletime was detected between short and long lines, and this difference might be related to the difference in mating time of Bactrocera cucurbitae. To examine this, we need to identify Drosophila melanogaster transjenic system, a null mutant of doubletime. Less