Does poor maternal condition reduce early offspring performance in the wild?

母亲对后代的投资程度在物种之间和物种内差异很大，可能会对这些后代的生存能力和存活率产生显著影响。任何母亲的贡献都受到母亲可用资源的限制，因此会随着她的营养状况(以及环境条件)的不同而变化。此外，如果母亲面临糟糕或不可预测的条件(因此无法预测子女的环境)，她们可能会改变子女的特征，作为一种生理约束或押注对冲策略，在整个家庭进行不平等的投资，增加至少一些人存活的可能性。然而，环境质量、雌性条件、后代变异性和后代表现之间的联系还没有被很好地理解。该项目将首次研究一个高度相关的问题，即环境变化导致野生鱼类种群平均母体状况的有据可查的下降，是否会影响后代应对更恶劣环境的能力。该项目将以大西洋鲑鱼为基础。近年来，由于冬季海面温度的升高，返回苏格兰河流产卵的雌性三文鱼的平均脂肪含量持续显著下降(每十年11%-14%)。这种条件的减少对卵子和由此产生的后代的影响尚不清楚。在这个项目中，我们将把雌性条件与一系列可能影响生存能力的卵子特征联系起来，并在一个独特而新颖的实验中，研究在不同水平的野外竞争下，母亲条件的变化对后代表现的影响。返回科农河产卵的鲑鱼将根据它们的身体状况进行分类，然后将状况良好和状况不佳的雌性鲑鱼的卵种植到由于上游无法通行的障碍而缺乏鲑鱼的自然溪流中。鱼苗的存活率将与它们母亲的身体状况有关，使用DNA指纹来确定每条重新捕获的鱼的父母。在这项实地工作的同时，我们将在实验室测量卵和鱼苗的各种特征，以确定母亲的身体状况如何影响后代的特征。

The extent to which mothers invest in their offspring varies greatly among and within species, and can have pronounced effects on the viability and survival of those offspring. Any maternal contribution is limited by the resources available to the mother, and so will vary with her nutritional state (and hence environmental conditions). Furthermore, if mothers face poor or unpredictable conditions (and so cannot predict the environment of their offspring), they may alter the characteristics of their offspring, either as a physiological constraint or as a bet-hedging strategy, by investing unequally across the family, increasing the possibility that at least some individuals will survive. However, the links between environmental quality, female condition, offspring variability and offspring performance are not well understood. This project will be the first to examine the highly pertinent question of whether a documented decline in average maternal condition in a wild fish population, caused by environmental change, is affecting the ability of offspring to cope with harsher environments. The project will be based on Atlantic salmon. The mean fat content of female salmon returning to Scottish rivers to spawn has shown a continuous and significant decrease in recent years (11-14% per decade), linked to increases in winter sea surface temperature. The effects of this reduction in condition on the eggs and the resulting offspring are unknown. In this project we will relate female condition to a diverse range of egg characteristics likely to influence viability, and in a unique and novel experiment will investigate the consequences of variation in maternal condition on offspring performance under differing levels of competition in the wild. Salmon returning to the River Conon to spawn will be classified according to their body condition, and eggs from females in good and poor condition will then be planted out into natural streams that lack salmon due to impassable upstream barriers. The survival rate of the fry will be related to the body condition of their mother, using DNA fingerprinting to establish the parents of each recaptured fish. In parallel with this field work we will measure various traits of the eggs and fry in the lab, to determine how the body condition of the mother influences the characteristics of the offspring.