Data and code for population dynamics of <i>Obama nungara </i>study

Population dynamics and the way abundance fluctuates over time may be key determinants of the invasion success of an introduced species. Fine-scale temporal monitoring of invasive species is rarely carried out due to the difficulties in collecting data regularly and over a long period. Thanks to the collaboration of an amateur naturalist, a unique dataset on the abundance of the invasive land flatworm <i>Obama nungara</i> was obtained during a four-year survey of a French private garden, where up to 1585 <i>O. nungara </i>were recorded in one month. Daily monitoring data revealed high population size fluctuations that may be explained by meteorological factors as well as intra- and inter-specific interactions. Bayesian modelling confirmed that <i>O. nungara’s </i>abundance fluctuates depending on temperature, humidity and precipitation. Population growth seems to be favoured by mild winters and precipitation while it is disadvantaged by drought. These exogenous factors affect both directly this species, which is sensitive to desiccation, and indirectly since they are known to affect the populations of its prey (earthworms and terrestrial gastropods). We also suggested the important resilience of <i>O. nungara </i>population in this site, which was able to recover from a drastic demographic bottleneck due to a severe drought, as well to systematic removal by the owner of the site. These findings highlight the potentially high invasiveness of <i>O. nungara</i> and raise concerns regarding the strong threat that these invasive flatworms represent for the populations of its prey.种群动态及其随时间变化的丰度波动模式，是决定外来物种入侵成功与否的核心影响因素。由于长期且定期开展数据收集存在诸多现实困难，针对入侵物种的精细尺度时间动态监测工作往往难以推进。得益于一位业余博物学者的协作支持，研究团队在对一处法国私人花园的四年定点调查中，获取了关于入侵性陆生扁形虫*Obama nungara*丰度的独特数据集——该调查中单月记录的*O. nungara*个体数最高可达1585只。每日监测数据显示，该物种种群规模存在剧烈波动，这种波动可由气象因素以及种内、种间相互作用共同解释。贝叶斯模型分析（Bayesian modelling）证实，*O. nungara*的丰度波动受温度、湿度与降水量的调控。温和的冬季与适量降水有利于种群增长，而干旱则会显著抑制其种群扩张。这些外源因素既会直接作用于这种对脱水敏感的物种，也会通过间接途径产生影响：已知气象条件会直接影响其猎物（蚯蚓与陆生腹足类）的种群规模。本研究同时指出，该调查样地内的*O. nungara*种群具备极强的恢复力——其既能在严重干旱引发的剧烈种群瓶颈中完成恢复，也能在该场地主人的系统性人工清除行动后重新恢复种群规模。上述研究结果凸显了*O. nungara*极高的潜在入侵性，同时也引发了学界对这类入侵扁形虫对其猎物种群构成严重威胁的广泛担忧。