Factors influencing Soay sheep survival
Factors influencing Soay sheep survival
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DOI：
10.1111/1467-9876.00205
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发表时间：
2000-01-01
影响因子：
1.6
通讯作者：
Albon, SD
中科院分区：
文献类型：
--
作者：
Catchpole, EA;Morgan, BJT;Albon, SD
我们提出了一个生存分析Soay羊标记夺回和恢复数据。与以前的条件分析不同，它不需要假设回收和再捕获概率相等，而是通过最大似然估计。雄性和雌性绵羊分别处理，雌性绵羊的数量和存活概率更高，导致模型比雄性绵羊更复杂。然而，在这两种情况下，需要包括年龄和时间方面，并且有强烈的迹象表明7岁或以上的绵羊的存活率降低。生存的时间变化与人口规模和选定的天气变量有关，通过使用逻辑回归。人口的大小显着影响的生存概率的男性和女性羔羊，和女性绵羊年龄在7岁或以上。三月的降雨量和北大西洋振荡的措施被认为是影响生存显着的所有年龄组，男性和女性。这些天气变量中的任何一个都可以在模型中使用。还拟合了几个表型和基因型个体协变量。唯一的协变量，这是发现影响生存显着是第一年的母羊的角的类型。随着时间的推移，恢复概率有很大的变化，部分反映了当预期人口崩溃时所增加的努力。用图解法检验了模型的拟合优度。
We present a survival analysis of Soay sheep mark recapture and recovery data. Unlike previous conditional analyses, it is not necessary to assume equality of recovery and recapture probabilities; instead these are estimated by maximum likelihood. Male and female sheep are treated separately, with the higher numbers and survival probabilities of the females resulting in a more complex model than that used for the males. In both cases, however, age and time aspects need to be included and there is a strong indication of a reduction in survival for sheep aged 7 years or more. Time variation in survival is related to the size of the population and selected weather variables, by using logistic regression. The size of the population significantly affects the survival probabilities of male and female lambs, and of female sheep aged 7 or more years. March rainfall and a measure of the North Atlantic oscillation are found to influence survival significantly for all age groups considered, for both males and females. Either of these weather variables can be used in a model. Several phenotypic and genotypic individual covariates are also fitted. The only covariate which is found to influence survival significantly is the type of horn of first-year female sheep. There is a substantial variation in the recovery probabilities over time, reflecting in part the increased effort when a population crash was expected. The goodness of fit of the model is checked by using graphical procedures.