Dissertation Research: Pattern and Process in Plant Physical Defenses Across a Latitudinal Gradient

许多植物被各种各样的昆虫吃掉，食草昆虫或食草昆虫有时会消耗植物每年生长的几乎一半的叶子。热带森林中的植物比温带森林中的植物更容易被昆虫吃掉，热带植物也更多样化。对于更高的多样性和更好的防御能力的一种解释可能是，昆虫在热带森林中比在温带森林中吃更多的叶子，选择防御能力更强的植物，防止少数植物物种占据优势。然而，目前还不清楚热带森林的食草性是否更高，因为之前的研究没有在大范围的纬度范围内以一致的方式测量食草性。本研究的目的是比较三个地点的昆虫对黄瓜科植物叶片的消耗，一个是热带（巴拿马），一个是亚热带（佛罗里达），一个是温带（威斯康辛）。为了保持树叶的营养成分和当地环境条件不变，研究人员将在温室中种植植物，然后将它们移植到每个地点的自然环境中。然后，他们将记录访问植物的昆虫的数量和类型，以及这些昆虫对每种植物的消耗。这将在每个地点的植物主要生长季节进行。这项研究将在结出果实和种子后结束，这将揭示食草动物对叶子的损害是如何影响植物的生育能力的。了解从热带气候到温带气候的草食变化将有助于预测气候变化如何改变未来的草食数量。例如，气温升高可能会导致热带昆虫向高纬度地区扩张，并增加温带地区可食用的植物数量。以吃庄稼的昆虫为例，这可能会影响农业。更多地了解当前的草食模式可以帮助人们通过诸如虫害控制管理的变化等措施来适应未来的变化。该项目还将为本科生提供研究培训，并向公立学校开展推广活动。

Many plants are eaten by a wide variety of insects, and herbivorous, or plant-eating, insects sometimes consume almost half of the leaves that a plant grows each year. Plants in tropical forests tend to be better defended against being eaten by insects than plants in temperate forests, and the tropical plants are also more diverse. One explanation for both higher diversity and better defense may be that insects eat more leaves in tropical forests than in temperate forests, selecting for plants with more defense and preventing dominance by just a few plant species. However, it is not really known whether herbivory is higher in tropical forests, because no previous studies have measured herbivory in a consistent way across a wide range of latitudes. The goal of this study is to compare the consumption of leaves of plants in the cucumber family by insects in three locations, one tropical (Panama), one subtropical (Florida), and one temperate (Wisconsin). To keep factors such as nutrient content of leaves and local environmental conditions constant, the investigators will grow plants in greenhouses and then transplant them into natural environments at each of the sites. They will then record the number and type of insects visiting the plants, and how much those insects consume of each plant. This will occur over the main growing season of the plants at each site. The study will end when fruits and seeds have been produced, which will reveal how herbivore damage to leaves can influence plant fertility. Understanding how herbivory changes from tropical to temperate climates will help predict how change in climate might change amounts of herbivory in the future. For example, rise in temperature might cause tropical insects to expand into higher latitudes and increase the amount of plants that are eaten in the temperate zone. In the case of insects that eat crops, this could impact agriculture. Knowing more about current patterns of herbivory may help people adapt to future change through measures such as changes in pest control management. This project will also provide research training for undergraduates and conduct outreach to public schools.