ADAPTATION AND PLASTICITY IN NEST CONSTRUCTION: BEHAVIOURAL AND MOLECULAR FACTORS AFFECTING DESIGN IN AN EXTENDED PHENOTYPIC TRAIT

筑巢是许多动物生殖行为的重要组成部分，从无脊椎动物到鸟类。父母建造巢作为卵和发育中的后代的容器，它们的设计对它们的功效有重要的影响。巢和其他动物结构被描述为扩展的表型特征/体外特征，但反映了建造者的基因。因此，我们可能会认为生活在不同环境中的物种群体进化出了不同的筑巢结构，这一过程被称为“适应性分化”。然而，就像传统特征是基因和环境相互作用的结果一样，动物建筑结构的设计也是由外部因素决定的。个体在面对环境变化时有益地调整行为模式的能力被描述为“表型可塑性”。在这个项目中，我们将研究三刺鱼筑巢行为中的适应性发散和表型可塑性。雄性刺鱼筑巢，为求偶提供了焦点，也为雌性提供了产卵的地方。我们选择刺鱼是因为(1)它们自然地占据并在从静止的池塘到湍急的溪流等广泛的水生栖息地筑巢；(2)它们非常适合实验室研究，所以我们已经对它们的生殖行为生态学有了很多了解；(3)它们的基因组最近被测序，使我们能够提出问题，即个体如何在分子和行为水平上调整筑巢。我们将进行一系列实验，使用来自不同种群的刺鱼，提出4个相关和重要的问题；一些刺鱼是从河流进化而来的，还有一些是来自湖泊的。首先，我们将研究在筑巢过程中所经历的流动状态和可用的材料类型是如何相互作用来决定巢的设计的。然后，我们将允许雄性在一种状态下(“静止”或“流动”)筑巢，然后在建造它的状态下和在相反的状态下测试其性能的各个方面(包括对高流速的抵抗力、对低氧气水平的敏感性，以及对雌性的吸引力)。这将量化建造一个不适合当前流动条件的鸟巢的成本。然后，我们将通过检查个体的筑巢行为和筑巢设计来检验雄鸟在环境变化时在多大程度上能够调整筑巢行为，首先是一个，然后是交替的流动制度。雄性刺鱼会分泌一种名为spiggin的胶水，用来将筑巢材料粘在一起，并将它们固定在基质上。最近的研究已经确定了肾脏中负责spiggin合成的基因。我们想知道雄性刺鱼是否可以通过改变spiggin基因的表达来调节spiggin的产生，以响应不断变化的流动条件。这可能会让雄鸟直接调整巢的强度，以应对不断变化的流速。因此，我们将从不同的人群中收集男性，并从受控流动机制下的男性被关押的实验中收集男性，并进行一项分析，以使肾脏中的基因产物(而不仅仅是它的存在/不存在)的数量被量化。我们的研究将是第一批考察适应性分化和表型可塑性在动物构造行为中的相对作用的研究之一，并且在结合行为和分子方法方面是独一无二的。我们的结果将显示，鱼类的筑巢行为在多大程度上适应了它们当地的环境，以及它们在条件变化时可以在多大程度上调整建造模式。了解行为可塑性的程度和局限性很重要，因为它将帮助我们预测物种引进和全球气候变化可能如何影响个体和种群的成功。

Nest building is an essential component of reproductive behaviour in many animals, from invertebrates to birds. Parents construct nests as receptacles for eggs and developing offspring, and their design has important implications for their efficacy. Nests and other animal constructions have been described as extended phenotypic traits / extra-body characteristics that nonetheless reflect the genotype of the builder. Hence, we might expect populations of a species living in different environments to have evolved different nest construction, a process called 'adaptive divergence'. However, just as conventional traits result from the interaction of genes and environment, so the design of animal built structures is shaped by external factors. The ability of individuals to adjust patterns of behaviour beneficially when faced with environmental change is described as 'phenotypic plasticity'. In this project, we will investigate adaptive divergence and phenotypic plasticity in the nest building behaviour of a fish, the 3-spined stickleback. Male sticklebacks build nests, which provide a focus for courtship and a place for females to lay eggs. We chose sticklebacks because (1) they naturally occupy, and build nests in, a wide range of aquatic habitats, from static ponds to fast flowing streams; (2) they are extremely well suited to laboratory studies, so we already know a great deal about their reproductive behavioural ecology; and (3) their genome has recently been sequenced, allowing us to ask questions about how individuals adjust nest building at molecular, as well as behavioural, levels. We will undertake a series of experiments to ask 4 related and important questions, using sticklebacks from different populations; some that have evolved in rivers, and some from lakes. First, we will examine how the flow regime experienced during nest building, and the type of materials available, interact to determine the design of nests. We will then allow males to build nests under one regime ('still' or 'flow') before testing aspects of its performance (including resistance to high flow rates, susceptibility to low oxygen levels, and attractiveness to females) under the regime in which it was built, and under the opposite regime. This will quantify the costs of building a nest that is unsuited to prevailing flow conditions. We will then examine to what extent males are able to adjust nest building behaviour when environments change, by examining building behaviour and nest design of individual males under first one, and then the alternate, flow regime. Male sticklebacks secrete a 'glue', Spiggin, which used to stick nesting materials together and anchor them to the substratum. Recent research has identified the genes responsible for Spiggin synthesis in the kidney. We want to know if male sticklebacks can regulate the production of Spiggin in response to changing flow conditions by altering the expression of Spiggin genes. This might allow males to adjust nest strength in direct response to changing flow rates. We will therefore collect males from the different populations, and also from experiments in which males are held under controlled flow regimes, and undertake an analysis that allows the amount of gene product (rather than just it presence/absence) in the kidney to be quantified. Our study will be among the first to examine the relative roles of adaptive divergence and phenotypic plasticity in animal construction behaviour, and is unique in incorporating both a behavioural and molecular approach. Our results will show to what extent the nest building behaviour of fish is adapted to their local environment, and to what extent they can adjust patterns of construction when conditions change. Understanding the extent and limitations of behavioural plasticity is important because, for example, it will help us predict how species introductions and global climate change are likely to affect success of individuals and of populations.