Census error and the detection of density dependence

作者：Robert P. Freckleton, Andrew R. Watkinson, Rhys E. Green, William J. Sutherland · 发表于：Journal of Animal Ecology · 年份：2006 · DOI：10.1111/j.1365-2656.2006.01121.x · 被引用次数：328 · 研究领域：Ecology and Vegetation Dynamics Studies、Animal Ecology and Behavior Studies、Species Distribution and Climate Change

1. Studies aiming to identify the prevalence and nature of density dependence in ecological populations have often used statistical analysis of ecological time-series of population counts. Such time-series are also being used increasingly to parameterize models that may be used in population management. 2. If time-series contain measurement errors, tests that rely on detecting a negative relationship between log population change and population size are biased and prone to spuriously detecting density dependence (Type I error). This is because the measurement error in density for a given year appears in the corresponding change in population density, with equal magnitude but opposite sign. 3. This effect introduces bias that may invalidate comparisons of ecological data with density-independent time-series. Unless census error can be accounted for, time-series may appear to show strongly density-dependent dynamics, even though the density-dependent signal may in reality be weak or absent. 4. We distinguish two forms of census error, both of which have serious consequences for detecting density dependence. 5. First, estimates of population density are based rarely on exact counts, but on samples. Hence there exists sampling error, with the level of error depending on the method employed and the number of replicates on which the population estimate is based. 6. Secondly, the group of organisms measured is often not a truly self-contained population, but part of a wider ecologic...