Fadini Rodrigo F, Cintra Renato
Programa de Pós-Graduação em Ecologia, Instituto Nacional de Pesquisas da Amazônia, CP 478, Manaus, 69067-375, AM, Brazil.
Coordenação de Biodiversidade, Instituto Nacional de Pesquisas da Amazônia, Manaus, 69067-375, AM, Brazil.
PLoS One. 2015 May 14;10(5):e0127004. doi: 10.1371/journal.pone.0127004. eCollection 2015.
The detection of an organism in a given site is widely used as a state variable in many metapopulation and epidemiological studies. However, failure to detect the species does not necessarily mean that it is absent. Assessing detectability is important for occupancy (presence-absence) surveys; and identifying the factors reducing detectability may help improve survey precision and efficiency. A method was used to estimate the occupancy status of host trees colonized by mistletoe seeds of Psittacanthus plagiophyllus as a function of host covariates: host size and presence of mistletoe infections on the same or on the nearest neighboring host (the cashew tree Anacardium occidentale). The technique also evaluated the effect of taking detectability into account for estimating host occupancy by mistletoe seeds. Individual host trees were surveyed for presence of mistletoe seeds with the aid of two or three observers to estimate detectability and occupancy. Detectability was, on average, 17% higher in focal-host trees with infected neighbors, while decreased about 23 to 50% from smallest to largest hosts. The presence of mistletoe plants in the sample tree had negligible effect on detectability. Failure to detect hosts as occupied decreased occupancy by 2.5% on average, with maximum of 10% for large and isolated hosts. The method presented in this study has potential for use with metapopulation studies of mistletoes, especially those focusing on the seed stage, but also as improvement of accuracy in occupancy models estimates often used for metapopulation dynamics of tree-dwelling plants in general.
在许多集合种群和流行病学研究中，在给定地点检测到某种生物被广泛用作一种状态变量。然而，未能检测到该物种并不一定意味着它不存在。评估可检测性对于占用情况（存在与否）调查很重要；识别降低可检测性的因素可能有助于提高调查的精度和效率。我们使用一种方法来估计被斜叶寄生 Psittacanthus plagiophyllus 的槲寄生种子定殖的寄主树的占用状态，该状态是寄主协变量的函数：寄主大小以及同一或最近相邻寄主（腰果 Anacardium occidentale）上是否存在槲寄生感染。该技术还评估了在估计寄主被槲寄生种子占用情况时考虑可检测性的影响。借助两到三名观察者对每棵寄主树进行调查，以估计可检测性和占用情况。平均而言，有受感染邻居的焦点寄主树上的可检测性高出 17%，而从最小到最大的寄主，可检测性降低约 23%至 50%。样本树上存在槲寄生植物对可检测性的影响可忽略不计。未能检测到被占用的寄主平均使占用率降低 2.5%，对于大型孤立寄主，最大降低 10%。本研究中提出 的方法有潜力用于槲寄生的集合种群研究，特别是那些侧重于种子阶段的研究，也可用于提高通常用于树栖植物集合种群动态的占用模型估计的准确性。
