Neuroscience Program, Trinity College of Arts & Sciences, Duke University, Durham, North Carolina, United States of America.
PLoS One. 2012;7(5):e37910. doi: 10.1371/journal.pone.0037910. Epub 2012 May 31.
Decision-making is defined as selection amongst options based on their utility, in a flexible and context-dependent manner. Oviposition site selection by the female fly, Drosophila melanogaster, has been suggested to be a simple and genetically tractable model for understanding the biological mechanisms that implement decisions. Paradoxically, female Drosophila have been found to avoid oviposition on sugar which contrasts with known Drosophila feeding preferences. Here we demonstrate that female Drosophila prefer egg laying on sugar, but this preference is sensitive to the size of the egg laying substrate. With larger experimental substrates, females preferred to lay eggs directly on sugar containing media over other (plain, bitter or salty) media. This was in contrast to smaller substrates with closely spaced choices where females preferred non-sweetened media. We show that in small egg laying chambers newly hatched first instar larvae are able to migrate along a diffusion gradient to the sugar side. In contrast, in contexts where females preferred egg laying directly on sugar, larvae were unable to migrate to find the sucrose if released on the sugar free side of the chamber. Thus, where larval foraging costs are high, female Drosophila choose to lay their eggs directly upon the nutritious sugar substrate. Our results offer a powerful model for female decision-making.
决策是指在灵活和依赖上下文的情况下，根据选项的效用进行选择。雌性果蝇的产卵地点选择被认为是一个简单且可遗传的模型，可用于理解实施决策的生物学机制。矛盾的是，人们发现雌性果蝇避免在糖上产卵，这与已知的果蝇进食偏好形成了对比。在这里，我们证明了雌性果蝇更喜欢在糖上产卵，但这种偏好对产卵基质的大小敏感。在较大的实验基质上，雌性果蝇更愿意直接将卵产在含糖的培养基上，而不是其他（普通、苦或咸）培养基上。相比之下，在较小的基质上，当有紧密间隔的选择时，雌性果蝇更喜欢非甜味的培养基。我们表明，在小的产卵室中，刚孵化的第一龄幼虫能够沿着扩散梯度迁移到糖侧。相比之下，如果在没有糖的一侧释放幼虫，在雌性果蝇更喜欢直接在糖上产卵的情况下，幼虫无法迁移到糖上寻找蔗糖。因此，在幼虫觅食成本较高的情况下，雌性果蝇选择直接在营养丰富的糖基质上产卵。我们的结果为雌性决策提供了一个强大的模型。
