School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom.
The Earlham Institute, Norwich Research Park, Norwich, United Kingdom.
J Evol Biol. 2024 Oct 10;37(10):1215-1224. doi: 10.1093/jeb/voae102.
Socially plastic behaviours are widespread among animals and can have a significant impact on fitness. Here, we investigated whether the socially plastic responses of female Drosophila melanogaster can evolve in predictable ways following long-term manipulation of adult sex ratio and adult nutrient availability. Previous reports show that female D. melanogaster respond plastically to their same-sex social environment and lay significantly fewer eggs after mating when previously exposed to other females. In this study, we tested 2 hypotheses, using females drawn from lines with an evolutionary history of exposure to variation in adult sex ratio (male-biased, female-biased or equal sex ratio) and adult nutritional environment (high or low quality). The first was that a history of elevated competition in female-biased regimes would select for increased plastic fecundity responses in comparison to females from other lines. The second was that these responses would also be magnified under poor nutritional resource regimes. Neither hypothesis was supported. Instead, we found that plastic fecundity responses were retained in females from all lines and did not differ significantly across any of them. The lack of differences does not appear to be due to insufficient selection, as we did observe significant evolutionary responses in virgin egg-laying patterns according to sex ratio and nutritional regime. The lack of variation in the magnitude of predicted plasticity is consistent with the idea that the costs of maintaining plasticity are low, benefits high, and that plasticity itself can be relatively hard wired.
社会可塑性行为在动物中广泛存在，并且可能对适应性有重大影响。在这里，我们研究了在长期操纵成年性别比例和成年营养供应的情况下，雌性黑腹果蝇的社会可塑性反应是否可以以可预测的方式进化。先前的报告表明，雌性黑腹果蝇对其同性社交环境表现出明显的可塑性反应，并且在之前暴露于其他雌性后，交配后产卵的数量明显减少。在这项研究中，我们使用来自经历过成年性别比例（雄性偏多、雌性偏多或性别比例均等）和成年营养环境（高质量或低质量）变化的进化历史的品系中的雌性来检验两个假设。第一个假设是，在雌性偏多的环境中，竞争加剧的历史将选择增加与其他品系的雌性相比，具有更多的可塑性繁殖反应。第二个假设是，在营养资源较差的情况下，这些反应也会放大。这两个假设都没有得到支持。相反，我们发现所有品系的雌性都保留了可塑性繁殖反应，并且它们之间没有明显的差异。缺乏差异似乎不是由于选择不足造成的，因为我们确实观察到了根据性别比例和营养供应的处女产卵模式发生了显著的进化反应。预测可塑性的幅度没有变化与维持可塑性的成本低、收益高的观点一致，并且可塑性本身可能相对难以改变。
