Habitat and meta-habitat: influence of environment and colonization history on co-distribution of hosts and symbionts

栖息地和元栖息地：环境和殖民历史对宿主和共生体共同分布的影响

• 批准号: 261485-2013
• 负责人: Proctor, Heather
• 金额: $ 1.97万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=631732
• 关键词: Habitat; meta; habitat; influence; environment

All multicellular organisms act as 'habitats' for smaller organisms that live symbiotically on or inside the bodies of the larger hosts, or in nests created by the hosts. For obligatory single-host symbionts, the body or nest of the host is the necessary habitat; if the host is absent from a given area, the symbiont cannot exist there. But presence of a host is no guarantee that the symbiont will also be present. Symbiont loss is most obvious for host species that are expanding their ranges. During such range-expansion, particular symbionts may be absent from the colonizing host individuals by chance, or spread of the symbionts may lag behind that of their host. The former phenomenon is the rationale for classical biological control, in which an invasive pest is relatively free of parasites, which are sought for in the original range of the pest and introduced to the new range. An example of the latter pattern is parasites of cane toads in Australia. Toads at the leading edge of their range expansion are free from lungworms, whose transmission properties result in their own distribution lagging years behind that of their hosts. For ectosymbionts, or endosymbionts with an external life stage, another factor may play a role in their geographical distribution: the habitat occupied by their host. Such symbionts are exposed to similar environmental variables as their hosts, and if they have a different tolerance to temperature, humidity, etc. than their hosts, there may be circumstances in which a habitat suitable for the host is inimical to the symbiont. Thus from the symbiont's point of view, not only the appropriate habitat (= host) is necessary, but also the appropriate habitat of that habitat (= metahabitat). The importance of metahabitat is well understood for parasites of plants, but has been little investigated as an explanatory factor for the geographical distribution of symbionts of animals. Here I describe several projects examining co-distribution patterns of geographically widespread hosts (birds, crayfish, amphipods) and their invertebrate parasites and commensals (mites & lice, ostracods, helminths). My students and I will test the roles of colonization history and local environmental conditions in determining whether symbionts are able to colonize new areas along with their hosts.

所有多细胞生物都充当“栖息地”，适用于较小的生物体，这些生物在较大宿主的体内或宿主创造的巢中共生。对于强制性的单人共生体，宿主的身体或巢是必要的栖息地。如果从给定区域不存在主机，则不能存在共生体。但是，主机的存在不能保证共生体也会存在。对于扩大其范围的寄主物种，共生体损失最为明显。在这种范围扩张期间，偶然地殖民的寄主个体可能不存在特定的共生体，或者共生群体的传播可能会落后于他们的宿主。前一种现象是经典生物控制的基本原理，其中侵入性害虫相对不含寄生虫，在害虫的原始范围内寻求并引入新范围。后一种模式的一个例子是澳大利亚甘蔗蟾蜍的寄生虫。射程扩展的前沿蟾蜍没有肺虫，其传输特性导致自己的分布落后于宿主的分布滞后。对于具有外部生命阶段的外胞菌素或内共生体，另一个因素可能在其地理分布中起作用：宿主占据的栖息地。这样的共生体暴露于与宿主相似的环境变量，如果它们对温度，湿度等的容忍度与宿主的容忍度不同，则可能在某些情况下，适合宿主的栖息地对Symbiont不利。因此，从共生体的角度来看，不仅需要适当的栖息地（=宿主），而且还必须是该栖息地的适当栖息地（= metahabitat）。对于植物的寄生虫而言，元哈比特的重要性是充分理解的，但对动物共生体的地理分布的解释性因素很少进行。在这里，我描述了几个项目，研究了地理上广泛的宿主（鸟类，小龙虾，两亲脚架）及其无脊椎动物寄生虫和共生（螨虫和虱子，奥斯特拉科德，helminths）的共同分布模式。我和我的学生将测试殖民历史历史和当地环境条件在确定共生体是否能够殖民新领域及其宿主的作用。