Data from: Small-scale and regional spatial dynamics of an annual plant with contrasting sexual systems

1.Plant demography is known to depend on both spatial dynamics and life history, but how these two factors interact is poorly understood. We conducted a longitudinal study of the wind-pollinated annual plant Mercurialis annua that varies geographically in its sexual system to investigate this interaction. 2.Metapopulation demographic models predict that regular population turnover should be a more common feature of monomorphic than dimorphic populations because males and females cannot found new populations by selfing but hermaphrodites can. We tested the prediction that rates of population turnover would be higher in monomorphic compared to dimorphic regions. 3.We surveyed 356 populations of M. annua along five regional transects in Morocco and the Iberian Peninsula over a three-year period to examine their demography and persistence. Each transect crossed a transition in the sexual system, from a monomorphic region where almost all populations were hermaphroditic to a dimorphic one in which most populations had separate sexes (males with females or hermaphrodites). 4.As predicted, rates of local apparent extinctions (i.e. the disappearance of adult plants) were nearly 50% higher in monomorphic compared to dimorphic regions. Local extinctions appeared to be driven by changes in vegetation cover, with extinctions tending to occur in sites in which perennial cover also declined. This suggests that disturbance is a primary agent of local extinctions. 5.We further examined the influence of regional dynamics on local demographic properties by investigating patterns of spatial autocorrelation in population density across years. We found positive spatial autocorrelations in plant densities within regions for both sexual systems. However, these positive autocorrelations extended over shorter distances in monomorphic regions, perhaps as a result of greater population flux in these regions. 6.Synthesis: Our study shows that population dynamics may be influenced by processes acting at a range of spatial scales: within patches, across patches within sites, and across sites within regions, as well as by life-history variation. In M. annua, regional variation in apparent extinction rates is affected by life history and implicated in regulating the geographical distribution of populations with different sexual systems.1. 植物种群统计学（plant demography）的动态同时受空间动态与生活史调控，但学界对二者的交互作用机制仍缺乏深入认知。本研究针对风媒传粉的一年生植物一年生山靛（Mercurialis annua）开展纵向追踪研究，该物种的性系统存在地理变异，旨在探究上述交互作用。 2. 集合种群统计学模型（metapopulation demographic models）预测，相较于二态种群，单态种群的种群周转（population turnover）更为普遍——究其原因，二态种群中的雄性与雌性个体无法通过自交建立新种群，而单态种群的雌雄同体个体则可完成这一过程。我们针对"单态区域的种群周转速率高于二态区域"这一假说开展了检验。 3. 本研究于三年周期内，沿摩洛哥与伊比利亚半岛的五条区域样带，对356个一年生山靛种群展开调查，以解析其种群动态与存续特征。每条样带均跨越性系统过渡带：从几乎所有种群均为雌雄同体的单态区域，延伸至多数种群拥有分离性别的二态区域——此类区域的种群多包含雄株与雌株，或雄株与雌雄同体个体。 4. 研究结果与预测一致：单态区域的局部表观灭绝（local apparent extinctions）速率——即成年植株消失的现象——较二态区域高出近50%。局部灭绝事件似乎由植被覆盖变化驱动，多发生在多年生植物覆盖度下降的样地中，这表明干扰是引发局部灭绝的主要动因。 5. 我们进一步通过分析多年间种群密度的空间自相关（spatial autocorrelation）模式，探究了区域动态对局域种群统计属性的影响。结果显示，两种性系统对应的区域内，植物密度均呈现正空间自相关。但单态区域内的正空间自相关覆盖距离更短，这或许是由于该区域内种群周转更为频繁所致。 6. 研究总结：本研究表明，种群动态可能受到多空间尺度下过程的共同调控：斑块内部、样地内的斑块之间、区域内的样地之间，同时也受生活史变异的影响。在一年生山靛中，表观灭绝速率的区域差异受生活史调控，并与不同性系统种群的地理分布格局调控密切相关。