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No evidence for fitness signatures consistent with increasing trophic mismatch over 30 years in a population of European shag Phalacrocorax aristotelis
Journal of Animal Ecology ( IF 4.8 ) Pub Date : 2020-11-01 , DOI: 10.1111/1365-2656.13376
Katharine Keogan 1, 2 , Sue Lewis 1, 3 , Richard J Howells 2, 3 , Mark A Newell 3 , Michael P Harris 3 , Sarah Burthe 3 , Richard A Phillips 4 , Sarah Wanless 3 , Albert B Phillimore 1 , Francis Daunt 3
Affiliation  

As temperatures rise, timing of reproduction is changing at different rates across trophic levels, potentially resulting in asynchrony between consumers and their resources. The match-mismatch hypothesis (MMH) suggests that trophic asynchrony will have negative impacts on average productivity of consumers. It is also thought to lead to selection on timing of breeding, as the most asynchronous individuals will show the greatest reductions in fitness. Using a 30-year individual-level data set of breeding phenology and success from a population of European shags on the Isle of May, Scotland, we tested a series of predictions consistent with the hypothesis that fitness impacts of trophic asynchrony are increasing. These predictions quantified changes in average annual breeding success and strength of selection on timing of breeding, over time and in relation to rising sea surface temperature (SST) and diet composition. Annual average (population) breeding success was negatively correlated with average lay date yet showed no trend over time, or in relation to increasing SST or the proportion of principal prey in the diet, as would be expected if trophic mismatch was increasing. At the individual level, we found evidence for stabilising selection and directional selection for earlier breeding, although the earliest birds were not the most productive. However, selection for earlier laying did not strengthen over time, or in relation to SST or slope of the seasonal shift in diet from principal to secondary prey. We found that the optimum lay date advanced by almost four weeks during the study, and that the population mean lay date tracked this shift. Our results indicate that average performance correlates with absolute timing of breeding of the population, and there is selection for earlier laying at the individual level. However, we found no fitness signatures of a change in the impact of climate-induced trophic mismatch, and evidence that shags are tracking long-term shifts in optimum timing. This suggests that if asynchrony is present in this system, breeding success is not impacted. Our approach highlights the advantages of examining variation at both population and individual levels when assessing evidence for fitness impacts of trophic asynchrony.

中文翻译:

没有证据表明欧洲长鸬鹬种群的健康特征与 30 年来不断增加的营养不匹配相一致

随着温度升高,不同营养级别的繁殖时间以不同的速度变化,可能导致消费者与其资源之间的不同步。匹配-不匹配假说(MMH)表明营养异步会对消费者的平均生产力产生负面影响。人们还认为,这会导致对繁殖时间的选择,因为最不同步的个体将表现出最大的适应性下降。使用苏格兰五月岛欧洲鸬鹬种群的 30 年个体水平的繁殖物候学和成功率数据集,我们测试了一系列预测,这些预测与营养异步的适应性影响正在增加的假设相一致。这些预测量化了平均每年繁殖成功率和繁殖时间选择强度随时间的变化以及与海面温度(SST)上升和饮食成分相关的变化。年平均(种群)繁殖成功率与平均产蛋日期呈负相关,但随着时间的推移,或与海温的增加或饮食中主要猎物的比例没有相关趋势,正如营养失配增加时所预期的那样。在个体层面,我们发现了早期繁殖的稳定选择和定向选择的证据,尽管最早的鸟类并不是生产力最高的。然而,对早期产蛋的选择并没有随着时间的推移而加强,或者与海温或饮食从主要猎物到次要猎物的季节性转变的斜率有关。我们发现,在研究期间,最佳产蛋日期提前了近四个星期,并且群体平均产蛋日期跟踪了这一变化。我们的结果表明,平均性能与种群繁殖的绝对时间相关,并且在个体水平上存在早期产蛋的选择。然而,我们没有发现气候引起的营养失配影响发生变化的适应性特征,也没有证据表明鸬鹚正在跟踪最佳时间的长期变化。这表明,如果该系统中存在异步,育种成功不会受到影响。我们的方法强调了在评估营养异步的适应性影响的证据时检查种群和个体水平上的变异的优势。
更新日期:2020-11-01
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