Meats A, Pike N, An X, Raphael K, Wang W Y S
School of Biological Sciences, Fruit Fly Research Centre, University of Sydney, Sydney, NSW 2006, Australia.
Genetica. 2003 Nov;119(3):283-93. doi: 10.1023/b:gene.0000003683.42395.51.
Bactrocera neohumeralis and Bactrocera tryoni are closely related tephritid fruit fly species. B. neohumeralis mates throughout the day (in bright light) and B. tryoni mates at dusk. The two species can also be distinguished by the colour of their calli (prothoracic sclerites) which are brown and yellow, respectively. The F1 hybrids can mate both in bright light just before dusk and during dusk and have calli that are partly brown and partly yellow. The F2 hybrids have a wider range of callus patterns and mating occurs more widely in the day as well as at dusk. We directly selected hybrid stocks for mating time, creating 'early' (day-mating) and 'late' (dusk-mating) lines. As an apparently inadvertent consequence, the two types of line respectively had predominantly brown and predominantly yellow calli and thus came to closely resemble the original two species in both behaviour and appearance. Lines that were evenly selected (half for day and half for dusk) essentially retained the mating pattern of F2 hybrids. Selection for callus colour alone also affected the distribution of mating times in a predictable way. We propose a genetical model to account for the results and discuss them in the light of the apparent maintenance of species integrity in nature.
新肩实蝇和昆士兰实蝇是密切相关的实蝇科果蝇物种。新肩实蝇全天（在强光下）交配，而昆士兰实蝇在黄昏时交配。这两个物种还可以通过它们的胼胝体（前胸硬化体）颜色来区分，分别为棕色和黄色。F1杂种在黄昏前的强光下和黄昏时都能交配，其胼胝体部分为棕色，部分为黄色。F2杂种有更广泛的胼胝体模式，交配在白天以及黄昏时更为广泛地发生。我们直接根据交配时间选择杂种群体，创建了“早”（白天交配）和“晚”（黄昏交配）品系。显然作为一个意外的结果，这两种品系分别主要具有棕色和黄色的胼胝体，因此在行为和外观上都与原来的两个物种非常相似。均匀选择（一半用于白天，一半用于黄昏）的品系基本上保留了F2杂种的交配模式。仅对胼胝体颜色进行选择也以可预测的方式影响了交配时间的分布。我们提出了一个遗传模型来解释这些结果，并根据自然界中物种完整性的明显维持情况对其进行讨论。
