Bee ecology and evolution in the context of global change

蜜蜂对许多农作物和野生植物的授粉起着至关重要的作用，然而，关于世界上约2万种野生蜜蜂，人们仍知之甚少。由于缺乏信息，很难知道野生蜜蜂将如何应对气候变化和物种引进等挑战，更不用说提出明智的管理建议了。我的研究项目将在解决昆虫生态学和进化生物学的基本问题的同时，对蜜蜂进行新的发现，并在有价值的领域、实验室和沟通技巧方面训练学生。未来五年，我们将努力实现三个目标。为了了解气候变化是如何影响美国西南部干旱程度日益严重的独居蜜蜂种群的，我们将建立在我的实验室现有的5年多站点数据集上，这些数据集包括蜜蜂繁殖、花朵丰度和温度。我们将评估巢蜂的繁殖产出如何受到蜜蜂出苗时间相对于开花时间的变化以及干旱对花蜜和花粉供应的影响。我们还将测量蜂巢内的温度，并测试温度升高是否会使蜜蜂寄生虫相对于宿主加速发育。2. 为了了解限制野生蜜蜂地理范围的因素，我们将研究北美东北部和落基山脉的独居蜜蜂，询问北部或高海拔范围的限制是否由温度、花宿主植物的丰度、季节长度或蜜蜂活动期和开花期之间的重叠程度决定。这些研究将帮助我们预测蜜蜂范围将如何应对气候变化和开花时间不同的非本地植物物种的到来。3. 我们将重新评估蜜蜂和植物之间的共同进化是如何产生蜜蜂多样性的。蜜蜂通常被认为对植物有益，但作为花粉消费者，它们与植物的关系也是敌对的。事实上，许多植物的花粉都含有防御性化学物质，这表明植物保护它们的花粉；相反，某些蜜蜂群体专注于看似防御的花粉类型，这表明它们已经进化到能够克服防御。我们将对专才蜂和通才蜂的花粉使用情况进行实地观察，综合公民科学数据，并进行实验室实验，测试(a)专才蜂和通才蜂使用不同花粉的能力，以及(b)不同花粉抵抗蜜蜂真菌病原体感染的能力。这些研究将为蜜蜂为什么专门研究某些花粉类型的假设提供第一次测试。研究结果将帮助我们预测新的花粉类型何时会被纳入蜜蜂的饮食中，并对哪些植物应该被纳入“传粉者友好”的花园提出更好的建议。总的来说，这项研究将为野生蜜蜂的进化史以及它们在快速变化的世界中的未来提供新的见解。

Bees are crucial for pollination of many crops and wild plants, yet much remains unknown about the world's ~20,000 wild bee species. The lack of information makes it difficult to know how wild bees will respond to challenges such as climate change and species introductions-let alone make informed management recommendations. My research program will make new discoveries about bees while addressing fundamental questions in insect ecology and evolutionary biology and training students in valuable field, laboratory, and communication skills. In the next five years, we will address three goals: 1. To understand how climate change is affecting solitary bee populations in the southwestern U.S., where drought severity is increasing, we will build on my lab's existing 5-year, multi-site dataset on bee reproduction, flower abundance, and temperature. We will assess how reproductive output of cavity-nesting bees is affected by shifts in the timing of bee emergence relative to flowering time, and by effects of drought on nectar and pollen availability. We will also measure temperatures inside bee nests and test whether warmer temperatures allow bee parasites to accelerate development relative to their hosts. 2. To understand the factors that limit geographic ranges of wild bees, we will study solitary bees in northeastern North America and the Rocky Mountains, asking whether northern or upper-elevation range limits are determined by temperature, abundance of floral host-plants, season length, or the extent of overlap between bee activity periods and flowering. These studies will help us predict how bee ranges will respond to climate change and arrival of non-native plant species with differing flowering times. 3. We will re-evaluate how coevolution between bees and plants has given rise to bee diversity. Bees are normally viewed as beneficial to plants, but as pollen consumers, their relationship with plants is also adversarial. Indeed, pollens of many plant species possess defensive chemicals, suggesting that plants protect their pollen; conversely, certain groups of bees specialize on seemingly defended pollen types, suggesting that they have evolved to overcome the defences. We will conduct field observations of pollen usage by specialist and generalist bee species, syntheses of citizen-science data, and laboratory experiments testing (a) abilities of specialist and generalist bees to use different pollens, and (b) abilities of different pollens to resist infection by fungal pathogens of bees. These studies will provide the first tests of hypotheses for why bees specialize on certain pollen types. The results will help us predict when newly available pollen types will be incorporated in bee diets and make better suggestions about which plants to include in "pollinator-friendly" gardens. Overall, this research will provide novel insights into the evolutionary history of wild bees as well as their future in a rapidly changing world.