ESTIMATING FLUCTUATING VITAL RATES FROM TIME-SERIES DATA: A CASE STUDY OF APHID BIOCONTROL
ESTIMATING FLUCTUATING VITAL RATES FROM TIME-SERIES DATA: A CASE STUDY OF APHID BIOCONTROL
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根据时间序列数据估算波动的生命率：蚜虫生物防治的案例研究
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
E. Nordheim
中科院分区：
文献类型：
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作者：
K. Gross;A. Ives;E. Nordheim
许多生态时间序列描述了种群动态。这些数据还间接提供了这些动态背后的生命率（例如出生率、死亡率）的信息，但从数据中提取这些信息可能很困难。在这里，我们提出了一种根据生态时间序列估计波动生命率的方法，通过使用模型将观察到的动态信息重新编码为有关未观察到的生命率的信息。该模型构建与大多数当前模型的不同之处在于，用关于生命率如何随时间变化的更保守的假设来代替关于决定人口动态的函数关系的强烈假设。因此，该方法是分析时间序列数据的工具，避免了对人口动态驱动机制的强烈假设。我们的工作的动机是研究威斯康星州中南部苜蓿中豌豆蚜的生物防治。尽管这一规定的来源尚不清楚，但豌豆蚜的数量始终保持在经济阈值以下。在这里，我们分析监测数据，以了解专业寄生蜂在蚜虫生物防治中发挥的作用。我们的建模方法使我们能够估计决定蚜虫动态（特别是寄生）的生命率，而无需对寄生与蚜虫或拟寄生物密度之间的关系做出任意假设。我们发现，虽然寄生现象大大抑制了蚜虫种群的增长率，但蚜虫种群增长率的下降与寄生现象的增加并不相符。因此，寄生不能解释田间观察到的蚜虫种群的密度依赖性调节。
Many ecological time series describe population dynamics. Indirectly, these data also provide information about the vital rates (e.g., birth rates, mortality rates) un- derlying these dynamics, but extracting this information from the data can be difficult. Here, we present a method for estimating fluctuating vital rates from ecological time series by using a model to re-code information in observed dynamics into information about unobserved vital rates. This model construction differs from most current models by re- placing strong assumptions about the functional relationships dictating population dynamics with more conservative assumptions about how vital rates change with time. Thus, this method is a tool for analyzing time-series data that avoids strong assumptions about the mechanisms driving population dynamics. Our work is motivated by studying the biological control of pea aphids in alfalfa in south-central Wisconsin. Pea aphid populations are consistently held below economic threshold, although the source of this regulation is unclear. Here, we analyze monitoring data to understand the role that a specialist parasitoid plays in aphid biocontrol. Our mod- eling methodology allows us to estimate the vital rates that determine aphid dynamics (in particular, parasitism) without making arbitrary assumptions about the relationship between parasitism and aphid or parasitoid density. We find that, while parasitism depresses aphid population growth rate substantially, declines in aphid population growth rates do not coincide with increases in parasitism. Therefore, parasitism cannot be responsible for the density-dependent regulation of aphid populations observed in the field.