Weakened portfolio effect in a collapsed salmon population complex
Weakened portfolio effect in a collapsed salmon population complex
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DOI：
10.1139/f2011-084
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发表时间：
2011-09-01
影响因子：
2.4
通讯作者：
Satterthwaite, William Hallowell
中科院分区：
文献类型：
--
作者：
Carlson, Stephanie Marie;Satterthwaite, William Hallowell
最近的研究强调了种群间多样性在促进种群复合体稳定方面的重要性。在这里，我们专注于加州的最近崩溃的秋季运行奇努克鲑鱼（Oncorhynchus tshawytscha），并询问是否投资组合效应诱导缓冲观察到整个复杂的层次结构，从个体人口的人口在一个流域（萨克拉门托，圣华金）的整个中央谷。一些缓冲时观察到的变异系数比较成人返回到一个给定的河流流域与其组成的人口，但不是当比较返回到整个中央谷与其组成的盆地，因为不成比例的许多鱼类返回到萨克拉门托盆地。此外，我们报告说，河流之间的人口动态的正相关性更强，在过去25年的研究相比，前25年。总之，这些结果表明，只有一个微弱的投资组合效应，近年来已经恶化的证据。尽管如此，我们还报告说，河流之间的相关性显着下降的距离，这表明一些生物复杂性仍然存在。我们的研究结果表明，加强投资组合效应的最大潜力将通过恢复圣华金盆地人口，这在低丰度目前贡献不大的整体缓冲能力，尽管低跨流域的相关性。
Recent research has highlighted the importance of interpopulation diversity in fostering the stability of population complexes. Here we focus on California's recently collapsed fall-run Chinook salmon (Oncorhynchus tshawytscha) and ask whether portfolio effect induced buffering is observed across the complexity hierarchy from individual populations to populations within a river basin (Sacramento, San Joaquin) to the entire Central Valley. Some buffering was observed when comparing the coefficient of variation in adult returns to a given river basin with its constituent populations but not when comparing returns to the entire Central Valley with its constituent basins because of disproportionately many fish returning to the Sacramento Basin. Moreover, we report that positive correlations in population dynamics between rivers were stronger in the last 25 years of the study compared with the first 25 years. Together, these results suggest evidence of only a weak portfolio effect that has deteriorated in recent years. Nonetheless, we also report that correlations between rivers decreased significantly with distance, suggesting that some biocomplexity remains. Our results suggest that the greatest potential for strengthening the portfolio effect would come through restoration of San Joaquin Basin populations, which at low abundance currently contribute little to the overall buffering capacity despite low cross-basin correlations.