AbstractIn this study, survival to adult stage, duration of development of the immature stages, egg micromorphology, DNA polymorphism, and reproductive compatibility were measured for early- and late-emerging phenotypes of Delia radicum Linneaus to determine whether both phenotypes had evolved differences other than the duration of puparial development and to find the most likely genetic system controlling the expression of both phenotypes. Survival to adult stage was not significantly different between the early- and late-emerging phenotypes. Random amplified polymorphic DNA (RAPD) primers tested suggest that it is possible to distinguish an early-emerging fly from a late-emerging fly. Furthermore, the results suggest that the early- and late-emerging phenotypes differ not only in the timing of adult emergence but also in their egg structure (egg micromorphology) and in their larval and puparial mortality. These two phenotypes are not reproductively or ecologically isolated. The genetic system controlling the expression of early and late emergers in a population of D. radicum is probably an adaptive strategy reducing predator and parasitoid pressures, optimizing resource utilization, and ensuring survival of D. radicum during atypical winters. This strategy could eventually lead to temporal sympatric speciation if there are changes in a few key loci responsible for host plant selection and fitness on a new host.
摘要 本研究测定了林尼厄斯蝇(Delia radicum Linneaus)早龄和晚龄表型的成虫存活率、未成熟期发育持续时间、卵微形态、DNA多态性和生殖相容性,以确定这两种表型是否存在除蛹发育持续时间以外的进化差异,并找到控制这两种表型表达的最可能的遗传系统。早发和晚发表型在成虫阶段的存活率没有显著差异。测试的随机扩增多态性 DNA(RAPD)引物表明,可以区分早出蝇和晚出蝇。此外,研究结果表明,早发和晚发表型不仅在成虫出现的时间上不同,而且在卵的结构(卵微形态)以及幼虫和蛹的死亡率上也不同。这两种表型在生殖或生态上并不隔离。控制滇金丝猴种群中早期和晚期成虫表达的遗传系统可能是一种适应性策略,可减少捕食者和寄生虫的压力,优化资源利用,确保滇金丝猴在非典型冬季存活。如果负责寄主植物选择和在新寄主上的适应性的几个关键基因座发生变化,这种策略最终可能会导致时间上的同域物种分化。