Byers James E, Blakeslee April M H, Linder Ernst, Cooper Andrew B, Maguire Timothy J
Departinent of Zoology, University of New Hampshire, Durham, New Hampshire 03824, USA.
Ecology. 2008 Feb;89(2):439-51. doi: 10.1890/06-1036.1.
Geographic variability in abundance can be driven by multiple physical and biological factors operating at multiple scales. To understand the determinants of larval trematode prevalence within populations of the marine snail host Littorina littorea, we quantified many physical and biological variables at 28 New England intertidal sites. A hierarchical, mixed-effects model identified the abundance of gulls (the final hosts and dispersive agents of infective trematode stages) and snail size (a proxy for time of exposure) as the primary factors associated with trematode prevalence. The predominant influence of these variables coupled with routinely low infection rates (21 of the 28 populations exhibited prevalence <12%) suggest broad-scale recruitment limitation of trematodes. Although infection rates were spatially variable, formal analyses detected no regional spatial gradients in either trematode prevalence or independent environmental variables. Trematode prevalence appears to be predominantly determined by local site characteristics favoring high gull abundance.
丰度的地理变异性可能由在多个尺度上起作用的多种物理和生物因素驱动。为了了解海洋蜗牛宿主滨螺种群内幼虫吸虫流行率的决定因素，我们在新英格兰的28个潮间带地点对许多物理和生物变量进行了量化。一个分层的混合效应模型确定海鸥的数量（感染性吸虫阶段的最终宿主和传播媒介）和蜗牛大小（暴露时间的一个指标）是与吸虫流行率相关的主要因素。这些变量的主要影响以及通常较低的感染率（28个种群中有21个种群的流行率<12%）表明吸虫存在广泛的补充限制。尽管感染率在空间上存在差异，但正式分析未检测到吸虫流行率或独立环境变量的区域空间梯度。吸虫流行率似乎主要由有利于高海鸥数量的当地地点特征决定。
