Parental responses to variation in egg odour during incubation

禽类亲本通过决定孵化开始时间、孵化温度、巢小气候和翻蛋率，直接影响胚胎发育的速度和成功率。然而，与胎生动物不同的是，在胎生动物中，发育中的胚胎可能会将它们的发育需求（例如通过激素）传达给它们的父母，从而对它们的发育环境产生有益的变化，这对卵子结合的胚胎来说并不那么容易。事实上，在胚胎发声系统发展到孵化期结束之前，胚胎似乎没有机会向孵化的父母传达它们的发育需求，因此胚胎也没有机会通过操纵父母的行为来影响它们的微环境（例如使环境变暖或变冷）。根据试验数据显示：(a)鸡蛋在孵化过程中释放的气味足以提供有关其生存能力和热需求的信息，以及(b)鸟类可以探测到这些气味，本提案旨在测试一个新的假设，即孵化过程中胚胎的需求可以通过鸡蛋产生的嗅觉线索来确定，而父母不仅能探测到这些线索，还能相应地改变自己的行为。具体来说，我将使用能够释放与真卵相匹配的合成气味的人造卵，测试(I)与“可育”对照（实验1）相比，父母是否更少关注没有嗅觉发育迹象的卵（即“气味”不育），以及（ii）父母是否对与低温卵一致的嗅觉线索做出反应，并采取旨在提高卵温的行为（实验2）。这项工作不仅将是对鸟类嗅觉工作的一个非常新颖的贡献，这仍然处于起步阶段，而且将是理解早期孵化过程中胚胎-亲本相互作用的第一步。拟议的实验结果将直接导致进一步的NERC资助申请，以探索这些相互作用对胚胎及其亲本的适应性后果，以及这些过程如何在自然巢穴和跨物种中运作。从长远来看，它还可能导致基于气味的系统的发展，从而在商业上和圈养繁殖计划期间监测卵子的发育。

Avian parents directly affect the rate and success of embryonic development by determining the onset of incubation, temperature during incubation, nest microclimate and the rate of egg turning. However, unlike in viviparous animals, where developing embryos can potentially communicate their developmental requirements to their parent (e.g. via hormones), resulting in beneficial changes to their developmental environment, this is not so easy for egg-bound embryos. Indeed, until the embryonic vocalisation system develops towards the end of the incubation period, there would appear little opportunity for embryos to convey their developmental requirements to incubating parents and therefore little opportunity for embryos to influence their microenvironment (e.g. to make it warmer or cooler) by manipulating parental behaviour.Based on pilot data showing that (a) eggs release odour throughout incubation that is sufficient to provide information on their viability and thermal requirements, and (b) that birds can detect these odours, this proposal aims to test the novel hypothesis that embryo requirements during incubation can be determined via olfactory cues produced by eggs, and that parents not only detect these cues, but alter their behaviour accordingly. Specifically, using artificial eggs that can release synthetic odours that match those produced by real eggs, I will test whether (i) parents pay less attention to eggs that show no olfactory signs of development (i.e., 'smell' infertile) compared to 'fertile' controls (Experiment 1), and (ii) parents respond to olfactory cues consistent with hypothermic eggs with behaviours intended to increase egg temperature (Experiment 2).This work will not only be an extremely novel contribution to the work on avian olfaction, which is still very much in its infancy, but will be the first step in understanding embryo-parent interactions during early incubation. The results of the proposed experiments will lead directly to further NERC funding applications to explore the fitness consequences of these interactions for embryos and their parent(s) and how these processes operate in natural nests and across species. In the longer term, it may also lead to the development of odour-based systems to monitor egg development both commercially and during captive breeding programmes.