Invertebrates as housekeepers and bodyguards: exploring the ecology of terrestrial and freshwater cleaning and defensive symbioses.

在清洁和防御共生中，体型较小的物种从体型较大的宿主物种那里清除碎片和/或寄生虫。这些关系的性质各不相同，从对寄主有益（=互惠）到中立甚至有害（=寄生）。我的实验室的研究项目将集中在三种广泛存在但尚未得到充分研究的清洁/防御互惠关系：羽毛螨和鸟类，支壳蠕虫和小龙虾，毛囊蠕虫和蜗牛。***(1)寄主上共生体的大小和位置是否影响清洗共生菌的功效？羽毛螨包括2600个已描述的物种，它们生活在鸟类的羽毛和皮肤上。长期以来，人们一直怀疑那些以飞行羽毛为食的昆虫是非寄生的。最近，我们通过肠道成分分析表明，这种关系可能是互惠的，螨虫作为微小的清洁工，吃掉宿主羽毛上潜在的危险微生物。我的实验室将在一个精细的尺度上研究这种关系，以评估螨虫在飞行羽毛中的分布如何影响和被羽毛之间和羽毛内部潜在食物来源的分布所影响。我们还将评估螨虫的大小如何影响它们在羽毛上的位置和限制它们可以吃的食物。***(2)共生体能否帮助寄主扩大活动范围？鳃纲蠕虫生活在小龙虾的身体上，根据物种和种群密度的不同，它们可以作为清洁互助者或寄生虫。直到最近，在阿尔伯塔省还没有枝状小龙虾，在那里，单一种类的本地小龙虾历史上仅限于阿尔伯塔省东北部的小比弗河流域。自1991年以来，小龙虾在阿尔伯塔省的活动范围大大扩大。原来的海狸河种群仍然缺乏小龙虾蠕虫，但在新范围的自然入侵部分，小龙虾带来了它们的共生蠕虫。蚯蚓的存在是否有助于小龙虾向上游自然扩张进入艾伯塔省？我们将操纵蠕虫负荷来评估它们如何影响宿主的适应性，包括在新殖民的水体中。是什么使共生关系对宿主由好变坏？这种微小的蠕虫是淡水蜗牛的共生体，这一点很不寻常。通常，蠕虫生活在蜗牛的外表面，在那里它们消耗由宿主运动激起的物质。有许多报道称C. limnaei吃寄生扁虫的幼虫。这可以保护它们的宿主免受感染。其他研究表明，当C. limnaei存在时，蜗牛会受到影响。我们将研究C. limnaei和它们的蜗牛宿主之间的生态关系，以确定蠕虫是否始终作为防御性互惠主义者，或者是否依赖于宿主物种，毛囊菌数量和基因型，或寄生扁形虫的种类。重要性：我们的研究结果将帮助研究人员了解清洁共生体如何影响鸟类和淡水动物的健康和生态成功。

In cleaning and defensive symbioses, smaller-bodied species remove debris and/or parasites from larger-bodied host species. The nature of these relationships can vary from helpful to the host (= mutualism) to neutral or even detrimental (= parasitism). My lab's research program will focus on three widespread but understudied cleaning/defensive mutualisms: feather mites and birds, branchiobdellid worms and crayfish, and Chaetogaster worms and snails.***(1) Does symbiont body size and location on the host influence efficacy of cleaning mutualisms? Feather mites include 2600 described species that live on and in the feathers and skin of birds. Those that live on flight feathers have long been suspected to be non-parasitic. Recently we have shown via gut-content analysis that the relationship may be mutualistic, with the mites serving as tiny cleaners that eat potentially dangerous microbes on the feathers of their hosts. My lab will examine this relationship at a fine scale to assess how mite distribution among flight feathers affects and is influenced by the distribution of potential food sources among and within feathers. We will also assess how size of mites affects their location on feathers and limits the food items they can eat. ***(2) Can symbionts aid range-expansion of their hosts? Branchiobdellid worms live on the bodies of crayfish and can act as cleaning mutualists or parasites, depending on species and population density. Until recently, branchiobdellids were absent from Alberta, where the single species of native crayfish was historically restricted to the small Beaver River drainage in northeastern Alberta. Since 1991, the crayfish has greatly expanded its range in Alberta. The original Beaver River population still lacks crayfish worms, but in the naturally invaded parts of the new range, the crayfish have brought along their symbiotic worms. Could the presence of worms have aided natural upstream expansion of crayfish into Alberta? We will manipulate worm loads to assess how they affect host fitness, including in newly colonized water bodies.***(3) What shifts symbioses from good to bad for the host? The tiny worm Chaetogaster limnaei is unusual in being a symbiont of freshwater snails. Typically, worms live on the outer surface of the snail where they consume material stirred up by host movement. There are many reports of C. limnaei eating larvae of parasitic flatworms. This may protect their hosts from infection. Other studies suggest that snails suffer when C. limnaei is present. We will investigate ecological relationships between C. limnaei and their snail hosts to determine whether worms consistently act as defensive mutualists, or if this is dependent on host species, Chaetogaster number and genotype, or species of parasitic flatworm.***Importance: What we learn will help researchers to understand how cleaning symbionts influence the health and ecological success of birds and freshwater animals.