Shorebird life histories at multiple levels of analysis

生物体有不同的生存和繁殖方式和时间表，被称为它们的“生活史策略”。这项研究解决了小型滨鸟物种之间以及物种内个体之间的生活史策略的差异。当特征对生物体的生存或繁殖成功有很大影响时，种群生物学家面临挑战，解释为什么这些特征的遗传变异持续存在。这项研究探索了允许这些特征的竞争形式共存的机制。我的工作主要是研究琵鹭(一种小型滨鸟)的繁殖行为和迁徙行为的差异。大多数关于生殖行为的研究都涉及到一种特殊的东半球琵鹭--短尾琵鹭(Philomachus Pugnax)，在繁殖季节，会出现三种不同类型的雄性：(1)争夺交配场所的领地雄性，(2)不打架，而是被招募到与正常领地雄性在其宫廷中会合的“卫星”雄性，以及(3)罕见的“模仿雌性”雄性，它们既不逃跑，也不向雌性展示，但仍会交配。我们正在研究这三种雄性如何在种群中维持自己，它们如何与雌性交配，行为如何受到荷尔蒙的调节，以及类型之间存在哪些遗传差异。对相关滨鸟物种的研究提出了一个问题，为什么一些雌性在一次繁殖尝试中与几个不同的雄性交配。我们正在测试有关雌性如何从拥有更多样化的基因后代中获益的理论。在最后一个物种--西部琵琶身上，我们正在确定迁徙距离如何影响未来的存活率和繁殖率。研究表明，迁徙距离较远的鸟类存活率较高，但繁殖频率低于迁徙时间较短的鸟类，这代表了一种“生活史上的权衡”。了解不同的生活史如何持续，有助于我们预测物种在面对环境变化时的适应能力。

Organisms have diverse ways and schedules to survive and reproduce, referred to as their "life history strategies". This research addresses differences in life history strategies between species of small shorebirds, and also among individuals within species. When characters have strong effects on an organism's survival or reproductive success, population biologists are challenged to explain why genetic variation for such characters persists. This research explores mechanisms that permit coexistence of competing forms of such traits. I work primarily with differences in reproductive behaviour and migration behaviour of sandpipers, small shorebirds. Most of the research on reproductive behaviour involves a peculiar old-world sandpiper, the Ruff (Philomachus pugnax), in which three distinct types of males occur during the breeding season: (1) territorial males that fight for mating courts, (2) "satellite" males that do not fight, but are instead recruited to join with the normally territorial males on their courts, and (3) rare "female mimic" males, which neither flight nor display to females, but nonetheless do mate. We are studying how these three kinds of males maintain themselves in populations, how they obtain matings with females, how behaviour is regulated hormonally, and what genetic differences exist among types. Studies with related shorebird species ask why some females mate with several different males during a single breeding attempt. We are testing theories about how females may gain from having more genetically diverse offspring. In a final species, the Western Sandpiper, we are determining how migration distance affects future survivorship and reproductive rates. It appears that birds that migrate farther have higher survivorship, but breed less often, than those with shorter migrations, which would represent a "life history tradeoff". Understanding how different life histories persist helps us predict how adaptable species will be in the face of environmental changes.