Dissertation Research: Indirect Interactions Mediated by Changing Plant Chemistry: Does Beaver Browsing Benefit Beetles?

9311210 Whitham的初步工作检测到了一种涉及海狸、叶甲虫和白杨树的相互作用：甲虫似乎提出了甲虫受益于海狸食草性的假设。棉白杨含有水杨素，这是一种有效防御哺乳动物食草动物的化学物质，但被甲虫隔离并用于自身防御，PI认为甲虫被海狸砍伐的树木吸引是因为重新萌芽的生长在营养上更优越，在化学上也得到了更好的防御。与那些喂食非萌芽生长的甲虫相比，喂食再生生长的甲虫发育得更快，成熟时体重更重，对捕食者的防御能力更强。这项研究扩展了之前的工作，以评估1)再生棉是甲虫更好的营养食物来源，2)再生棉含有更多直接有益于甲虫的防御性化学物质。这项研究还研究了海狸食草性在影响甲虫分布方面的重要性，并将通过谴责其他河流系统来检验这种相互作用的普遍性。远亲税种之间的间接相互作用很少被详细研究。目前的研究主要集中在这种互动上。在棉杨系统中识别这一点很重要，因为海狸是可以改变景观水平环境的关键物种，而棉杨目前正在美国西部遭受广泛的枯萎。***

9311210 Whitham Primary work has detect an interaction involving beavers, leaf beetles, and cottonwood trees: beetles appear to hypothesis that beetles benefit from beaver herbivory. cottonwoods contain salicin, a chemical that is an effective defense against mammalian herbivores but is sequestered and used by the beetles for their own defense, the PIs pose that beetles are attracted to beaver-cut trees because the resprout growth is both nutritionally superior and chemically better defended. Beetles fed resprout growth develop faster, weigh more at maturity, and are better defended against predators than those fed nonresprout growth. This study expands previous work to assess whether 1) resprout cottonwood is nutritionally a better food resource for beetles and 2) resprout cotton wood contains more defensive chemicals that directly benefit the beetles. The study also examines the importance of beaver herbivory in affecting the distribution of beetles and will examine the generality of this interaction by censuring other river systems. %%% Indirect interactions between distantly related taxed have rarely been studied in detail. The current study focuses on such on interaction. This is important to identify in the cottonwood system because beavers are keystone species that can alter the environment at the landscape level, & cottonwoods are currently suffering widespread dieback in the western US.. ***