Detecting critical periods in larval flatfish populations
Detecting critical periods in larval flatfish populations
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DOI：
10.1016/s1385-1101(01)00058-2
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发表时间：
2001-06-01
影响因子：
2
通讯作者：
Lewis, SJ
中科院分区：
文献类型：
--
作者：
Chambers, RC;Witting, DA;Lewis, SJ
我们评估了死亡的时间过程和死亡率增加的时期（即关键时期）的证据，在实验室种群的幼体比目鱼。首先，我们对鱼类幼虫的死亡年龄和丰度数据进行了区分，后者在自然种群研究中是典型的。接下来，我们描述了年龄和温度依赖性的冬季比目鱼幼虫死亡率的实验研究，Pseudopleuronectes americanus。不同水温（7度、10度、13度和16度）下，这些种群的生存曲线在死亡幅度和时间过程上存在显著差异。在温度较低的地区，死亡率最高，并集中在幼虫生命的第三季度，主要与幸存的群体成员定居同时发生。在分析生存数据的统计方法中，具有时变协变量的比例风险模型被证明最能捕捉特定年龄的死亡率模式。我们的结论是，对基于高年龄死亡率（随环境条件而变化）时期的招募假设（例如，Hjort的关键时期假设）进行公平评估将需要：(1)基于年龄而不是时间的数据；(2)比目前普遍可用的数据具有更高的时间分辨率；(3)对生存曲线不规则性敏感的分析方法。我们提出了评估自然界关键时期的四种研究方法。(C) 2001 Elsevier Science B.V.版权所有
We evaluate the time-course of deaths and evidence of periods of increased mortality (i.e., critical periods) in laboratory populations of larval flatfish. First, we make the distinction between age-at-death and abundance-at-time data for fish larvae, the latter being typical in studies of natural populations. Next, we describe an experimental investigation of age-and temperature-dependent mortality in larval winter flounder, Pseudopleuronectes americanus. The survivorship curves of these populations differed significantly in both the magnitude and time-course of mortality among the four water temperatures evaluated (7, 10, 13, and 16 degreesC). Mortality was highest in the cooler temperatures and concentrated in the third quarter of larval life, largely concurrent with settlement of surviving members of the cohort. Among the statistical methods for analysing survival data, the proportional-hazards model with time-varying covariates proved best at capturing the patterns of age-specific mortalities. We conclude that fair appraisals of recruitment hypotheses which are predicated on periods of high, age-specific mortality that vary with environmental conditions (e.g., Hjort's critical period hypothesis) will require: (1) data that are based on age, not time; (2) data that are of higher temporal resolution than commonly available at present and (3) analytical methods that are sensitive to irregularities in survivorship curves. We suggest four research approaches for evaluating critical periods in nature. (C) 2001 Elsevier Science B.V. All rights reserved.