Data from: The "Woman in Red" Effect: pipefish males curb pregnancies at the sight of an attractive female

In an old Gene Wilder movie, an attractive woman dressed in red devastated a man’s current relationship. We have found a similar “Woman in Red” effect in pipefish, a group of fish where pregnancy occurs in males. We tested for the existence of pregnancy blocks in pregnant male black-striped pipefish (Syngnathus abaster). We allowed pregnant males to see females that were larger and even more attractive than their original high-quality mates and monitored the survival and growth of developing offspring. After exposure to these extremely attractive females, males produced smaller offspring in more heterogeneous broods and showed a higher rate of spontaneous offspring abortion. Although we did not observe a full pregnancy block, our results show that males are able to reduce investment in current broods when faced with prospects of a more successful future reproduction with a potentially better mate. This “Woman in Red” life history trade-off between present and future reproduction has similarities to the Bruce effect, and our study represents the first documentation of such a phenomenon outside mammals.在吉恩·怀尔德的一部老电影《红衣女郎》（The Woman in Red）中，一名身着红衣的迷人女子摧毁了一名男子的现有恋情。我们在海龙（pipefish）这类由雄性承担妊娠过程的鱼类中，发现了类似的"红衣女郎"效应。本研究以怀孕的黑纹海龙（Syngnathus abaster）为对象，检测了妊娠阻断现象是否存在：我们让怀孕的雄性个体接触体型比其原配优质雌性更大、更具吸引力的雌性，并监测其发育中幼崽的存活与生长情况。接触这类极具吸引力的雌性后，雄性所育幼崽的体型更小，育幼种群的异质性更高，且幼崽自发性流产率显著升高。尽管未观测到完全的妊娠阻断现象，但研究结果表明，当雄性面临与更优质配偶开展更成功的未来繁殖的前景时，能够降低对当前育幼种群的投入。这种当前繁殖与未来繁殖间的"红衣女郎"生活史权衡效应与布鲁斯效应（Bruce effect）具有相似性，而本研究是首次在哺乳类之外记录到此类现象。