Ecological Genetic Study of clock gene which can cause speciation

以瓜蝇（双翅目：绢蝇科）为研究对象，解释了时钟基因多效性控制生活史和行为特征导致生殖隔离的机制。瓜蝇每天在黄昏交配一次。选择生活史性状的种群在白天的交配时间表现出相关的反应。例如，被选择为较快（较慢）发育的苍蝇种群交配时间较早（较晚）。生理节律控制着交配的时间。在持续黑暗条件下，短发育品系的生理周期约为22小时，长发育品系的生理周期约为31小时。选种间杂交数据表明，发育周期由一个多基因控制，而昼夜节律可能由单个时钟基因控制。这些结果表明，一个时钟基因多效性地控制着瓜蝇的发育和循环。生殖隔离往往是适应不同环境或栖息地的间接（多效性）结果。例如，暂时或季节性抵消的生态位可以选择具有不同发育特征的生物。这些发育差异可能通过包括交配活动模式变化在内的各种方式无意中造成生殖隔离。通过配偶选择测试，选择发育时期的种群之间交配时间的差异转化为显著的前合子隔离。种群间交配时间差异大于1 h时，分离指数显著高于0。这些发现表明，可以通过时钟基因的多效性效应来建立早熟分离。有许多例子表明，繁殖时间的差异阻碍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。在这样的有机体中；如果昼夜节律与生殖性状之间存在遗传相关性，那么对生活史性状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。自然种群在繁殖时间上的分歧可以通过漂变、直接的自然选择或遗传相关的副产品来实现。无论如何，生物钟基因是生殖隔离的关键。我们还分析了短、长发育周期系中被称为时钟基因的周期和双周期基因的氨基酸序列。短系和长系在双时间上有一点氨基酸差异，这种差异可能与葫芦小实蝇交配时间的差异有关。为了验证这一点，我们需要鉴定黑腹果蝇转基因系统，一个双倍的零突变体。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