Laboratorio Ecotono, INIBIOMA, CONICET-Universidad Nacional del Comahue, Quintral 1250, 8400, Bariloche, Río Negro, Argentina.
Instituto de Ecología Regional, CONICET-Universidad Nacional de Tucumán, CC 34 Yerba Buena, 4107, Tucumán, Argentina.
Plant Biol (Stuttg). 2021 Jul;23(4):612-620. doi: 10.1111/plb.13264. Epub 2021 May 12.
The complexity of natural communities is the result of interactions among species that coexist within them. Parasitic interactions are among the most common species interaction types, and analysis of parasite-host ranges can advance understanding of how host-parasite pairs structure community interactions across their geographic distributions. Using network analysis and host preference relative index, we analysed host use by the South American mistletoe, Tristerix corymbosus (Loranthaceae), in 22 localities among two biomes: Chilean matorral and temperate forest. The total number of host species recorded was 27, and 40% of these species were non-native. The non-native Populus sp. was shared between biomes. There was a positive relationship between host range and potential host species richness at the studied localities. On average, the mistletoe parasitized each host species relative to its abundance. However, some host species in some localities are more parasitized than expected. Network structure showed a differences in host use between the two biomes: Aristotelia chilensis was central in the temperate forest, with Populus sp. in the Chilean matorral. Host use intensity in the Chilean matorral was higher for non-native species. Tristerix corymbosus has a wide host range and could be considered a generalist parasite across its full geographic distribution, but at local scales, host preferences differed among localities and are related to host coverage. Alterations in community composition, due to natural events or human activities, can modify the availability of possible hosts. Hence, the mistletoe with the described characteristics may be able to change its infection preference while maintaining the interaction functionality.
自然群落的复杂性是其内部共存物种相互作用的结果。寄生相互作用是最常见的物种相互作用类型之一，对寄生虫-宿主范围的分析可以增进对宿主-寄生虫对在其地理分布范围内构建群落相互作用的理解。我们使用网络分析和宿主偏好相对指数，分析了 22 个地点的两种生物群落（智利灌木丛和温带森林）中，南美槲寄生 Tristerix corymbosus（桑寄生科）对宿主的利用。记录的总宿主物种数为 27 种，其中 40%是非本地物种。非本地的杨属 Populus sp. 在两个生物群落中都有分布。研究地点的宿主范围与潜在宿主物种丰富度之间存在正相关关系。槲寄生相对其丰度寄生了每个宿主物种，但在一些地点的一些宿主物种被寄生的程度超过了预期。网络结构显示了两个生物群落之间宿主利用的差异：智利酒果 Aristotelia chilensis 在温带森林中处于中心地位，而智利灌木丛中的 Populus sp.。智利灌木丛中的宿主利用强度对于非本地物种更高。Tristerix corymbosus 有广泛的宿主范围，可以被认为是其整个地理分布范围内的泛化寄生虫，但在局部尺度上，宿主偏好因地点而异，并且与宿主覆盖率有关。由于自然事件或人类活动引起的群落组成的变化可能会改变可能宿主的可用性。因此，具有描述特征的槲寄生可能能够在保持相互作用功能的同时改变其感染偏好。
