Multiscale seasonal factors drive the size of winter monarch colonies
Multiscale seasonal factors drive the size of winter monarch colonies
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DOI：
10.1073/pnas.1805114116
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发表时间：
2019-04-23
影响因子：
11.1
通讯作者：
Zipkin, Elise F.
中科院分区：
文献类型：
--
作者：
Saunders, Sarah P.;Ries, Leslie;Zipkin, Elise F.
自1996年观察到的高峰以来，北美东部的黑脉金斑蝶在墨西哥越冬地减少了84%。然而，来自美国北部繁殖地的粗尺度种群指数并未显示出一致的下降趋势。这种差异导致人们猜测，秋季迁徙可能是一个关键的限制期。我们通过研究秋季影响帝王蝶的多尺度过程的作用来解决这一假设，并在12年期间（2004-2015年）使用所有已知冬季殖民地的到达丰度进行评估。我们量化了大陆尺度（气候、景观绿化和疾病）和局部尺度（群落栖息地质量）对冬季群落大小时空趋势的影响。我们还考虑了夏季高峰和迁徙人口指数的影响。我们的研究结果表明，北部繁殖地夏季丰度较高，导致冬季蜂群数量增加，秋天也更绿，这是美国南部花卉走廊花蜜供应增加的一个代表。群落大小也与当地茂密森林覆盖的数量以及是否位于黑脉金斑蝶生物圈保护区内呈正相关，但不受发病率的影响。尽管我们展示了夏季和精细尺度冬季种群规模之间的人口统计学联系，但我们也揭示了秋季迁徙期间和高峰期经历的条件影响了年度动态。如果在气候变化的影响下，植物资源和冬季栖息地的可用性减少，君主将面临越来越大的威胁。我们的研究解决了帝王蝶年度周期中一个长期存在的空白，并强调了评估迁徙条件对理解控制长期人口趋势的机制的重要性。
Monarch butterflies in eastern North America have declined by 84% on Mexican wintering grounds since the observed peak in 1996. However, coarse-scale population indices from northern US breeding grounds do not show a consistent downward trend. This discrepancy has led to speculation that autumn migration may be a critical limiting period. We address this hypothesis by examining the role of multiscale processes impacting monarchs during autumn, assessed using arrival abundances at all known winter colony sites over a 12-y period (2004-2015). We quantified effects of continental-scale (climate, landscape greenness, and disease) and local-scale (colony habitat quality) drivers of spatiotemporal trends in winter colony sizes. We also included effects of peak summer and migratory population indices. Our results demonstrate that higher summer abundance on northern breeding grounds led to larger winter colonies as did greener autumns, a proxy for increased nectar availability in southern US floral corridors. Colony sizes were also positively correlated with the amount of local dense forest cover and whether they were located within the Monarch Butterfly Biosphere Reserve, but were not influenced by disease rates. Although we demonstrate a demographic link between summer and fine-scale winter population sizes, we also reveal that conditions experienced during, and at the culmination of, autumn migration impact annual dynamics. Monarchs face a growing threat if floral resources and winter habitat availability diminish under climate change. Our study tackles a long-standing gap in the monarch's annual cycle and highlights the importance of evaluating migratory conditions to understand mechanisms governing long-term population trends.