Range expansion and population dynamics of an invasive species: the Eurasian Collared-Dove (Streptopelia decaocto)

Invasive species offer ecologists the opportunity to study the factors governing species distributions and population growth. The Eurasian Collared-Dove (Streptopelia decaocto) serves as a model organism for invasive spread because of the wealth of abundance records and the recent development of the invasion. We tested whether a set of environmental variables were related to the carrying capacities and growth rates of individual populations by modeling the growth trajectories of individual populations of the Collared-Dove using Breeding Bird Survey (BBS) and Christmas Bird Count (CBC) data. Depending on the fit of our growth models, carrying capacity and growth rate parameters were extracted and modeled using historical, geographical, land cover and climatic predictors. Model averaging and individual variable importance weights were used to assess the strength of these predictors. The specific variables with the greatest support in our models differed between data sets, which may be the result of temporal and spatial differences between the BBS and CBC. However, our results indicate that both carrying capacity and population growth rates are related to developed land cover and temperature, while growth rates may also be influenced by dispersal patterns along the invasion front. Model averaged multivariate models explained 35–48% and 41–46% of the variation in carrying capacities and population growth rates, respectively. Our results suggest that widespread species invasions can be evaluated within a predictable population ecology framework. Land cover and climate both have important effects on population growth rates and carrying capacities of Collared-Dove populations. Efforts to model aspects of population growth of this invasive species were more successful than attempts to model static abundance patterns, pointing to a potentially fruitful avenue for the development of improved invasive distribution models.

入侵物种为生态学家提供了研究调控物种分布与种群增长关键因子的绝佳契机。欧亚领鸽（Eurasian Collared-Dove，*Streptopelia decaocto*）凭借其丰富的种群丰度记录与近期发生的入侵过程，成为入侵扩散研究的模式生物。本研究利用繁殖鸟类调查（Breeding Bird Survey, BBS）与圣诞鸟类统计（Christmas Bird Count, CBC）数据，通过拟合领鸽种群的增长轨迹，探究了一系列环境变量与单个种群的环境容纳量（carrying capacity）及种群增长率之间的关联。根据增长模型的拟合效果，研究人员提取了环境容纳量与种群增长率参数，并利用历史因子、地理因子、土地覆被因子与气候因子作为预测变量构建模型。本研究采用模型平均（model averaging）法与单变量重要性权重（variable importance weights）法，评估了各预测变量的解释效力。不同数据集（BBS与CBC）中，在模型中获得最高支持度的特定变量存在差异，这可能源于两类调查在时间与空间尺度上的差异。然而，研究结果显示，种群环境容纳量与增长率均与城镇开发土地覆被及温度显著相关，而种群增长率还可能受到入侵前沿扩散格局的影响。经模型平均后的多元模型分别解释了35%~48%的环境容纳量变异与41%~46%的种群增长率变异。本研究结果表明，大范围的物种入侵事件可通过可预测的种群生态学框架开展评估。土地覆被与气候均对领鸽种群的增长率与环境容纳量具有重要调控作用。针对该入侵物种种群增长相关特征的建模工作，相较于静态种群丰度模式的建模尝试取得了更佳效果，这为开发更精准的入侵物种分布模型指明了颇具潜力的研究方向。