Behavioural and evolutionary ecology of avian brood parastism

禽类寄生的行为和进化生态学

• 批准号: 9556-2009
• 负责人: Sealy, Spencer
• 金额: $ 1.38万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=474568
• 关键词: Behavioural; evolutionary; ecology; avian; brood

Obligate brood parasites lay their eggs in nests of other species of birds, thus depending on the hosts to rear their offspring. As most hosts produce fewer young, adaptations for successful parasitism are countered by increasingly sophisticated adaptations by hosts that minimize the effects of parasitism or the likelihood that it will occur. Focusing primarily on parasitic cowbirds in North America, with comparative work on cuckoos in the old world, we are studying this interaction from the standpoints of parasite and host. Once believed to parasitize any nests they happened upon, cowbirds are now known to use some hosts more than others; this is not surprising because cowbirds lay fewer eggs than previously believed. They seem to select only certain hosts, perhaps the best ones. Studying cowbirds and hosts in different habitats, we are exploring the idea that selective host use increases a cowbird's reproductive success. With experiments, we are identifying attributes of hosts that may cause cowbirds to lay non-randomly: (1) nest defense and acquisition of requisite behaviour, (2) nest placement, (3) tolerance of parasitism, and (4) host quality. We are comparing differences within and among species that influence host use, such as size, aggressiveness at nests, parasitism of already-parasitized nests (and its conservation implications), egg-discrimination capabilities, and costs of acceptance versus rejection of cowbird eggs. We will focus mainly on host tolerance and host quality, building in part on our discovery 15 years ago of a small species that ejects cowbird eggs. Experiments will extend work on limits of how hosts see cowbird eggs and their own eggs relative to their abilities to recognize foreign eggs, and on bill-size constraints, answering the pervasive question of why so many host species tolerate costly parasitism. Knowing the minimum physical requirements for ejection and host-specific costs of acceptance is essential for understanding whether equilibrium or lag better explains acceptance in each host species. Rejection costs may explain acceptance in some hosts (equilibrium), whereas lag explains it in hosts that cannot recognize cowbird eggs.

专性育雏寄生虫将卵产在其他鸟类的巢中，从而依赖宿主来养育后代。由于大多数宿主产生的后代较少，成功寄生的适应性被宿主日益复杂的适应性所抵消，这些适应性使寄生的影响或发生的可能性最小化。主要集中在北美的寄生燕八哥，在旧世界的杜鹃的比较工作，我们正在研究这种相互作用的寄生虫和主机的观点。曾经人们认为燕八哥会寄生在它们所遇到的任何巢穴中，现在人们知道燕八哥比其他人更喜欢使用某些宿主;这并不奇怪，因为燕八哥产的蛋比以前认为的要少。它们似乎只选择某些宿主，也许是最好的宿主。研究燕八哥和不同栖息地的宿主，我们正在探索选择性宿主使用增加燕八哥繁殖成功率的想法。通过实验，我们确定了可能导致燕八哥非随机产卵的宿主属性：（1）巢防御和必要行为的获得，（2）巢的放置，（3）寄生的耐受性，以及（4）宿主质量。我们正在比较物种内部和物种之间的差异，影响主机的使用，如大小，侵略性的巢，寄生已经寄生的巢（及其保护意义），蛋歧视能力，并接受与拒绝燕八哥蛋的成本。我们将主要关注宿主耐受性和宿主质量，部分建立在我们15年前发现的一个小物种上，这个物种能孵化燕八哥的蛋。实验将扩展宿主如何看到燕八哥蛋和自己的蛋相对于它们识别外来蛋的能力的限制，以及账单大小的限制，回答为什么这么多宿主物种容忍昂贵的寄生的普遍问题。了解弹射的最低物理要求和接受的宿主特异性成本对于理解平衡或滞后是否更好地解释每个宿主物种的接受是至关重要的。拒绝成本可以解释接受在某些主机（均衡），而滞后解释它在主机不能识别燕八哥蛋。