Paleoecology of butterfly and moth populations

蝴蝶和蛾种群的古生态学

• 批准号: RGPIN-2021-02753
• 负责人: Cwynar, Les
• 金额: $ 2.19万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=745976
• 关键词: Paleoecology; butterfly; moth; populations

Eastern spruce budworm (SBW) is a major disturbance agent of eastern North American forests, reaching epidemic proportions on a 25-40 year cycle. These outbreaks can have severe economic impacts; the SBW outbreak of 1967-1993 affected 50 M hectares of forest in eastern North America, with an estimated loss of 44 million m3 of timber per year of the cycle. Economic models indicate potential losses of $10.8 - 15.3 billion in Atlantic Canada during an outbreak. Disturbances are often classified based on their extent, severity, duration, and frequency. As climate warming continues to change landscapes worldwide, researchers are attempting to understand and predict how these aspects of disturbance are likely to change and how those changes may necessitate changes in forest management practices. Understanding the past relationships between moth outbreaks and climate will reveal how outbreaks are expected to change in the future and allow us to adapt appropriate management strategies. Unfortunately, the influence of a changing climate on the frequency, duration and severity of SBW outbreaks is largely unknown, mostly because 1) only two outbreaks have been studied in any detail because of their great length, and 2) the interactions of SBW with its hosts, predators, parasites, and climate are extremely complex and largely unknown. One objective of the proposed research program is to determine how the frequency, duration and severity of SBW outbreaks are related to climate. We will use a novel method to study past moth populations. Moth and butterfly wings are covered by microscopic scales of different shapes and sizes that are made of chitin, which preserves well in lake sediments. I will reconstruct the outbreak history of SBW from lake sediments for two contrasting climate periods -The Medieval Climate Anomaly (also called the Medieval Warm Period), when it was warmer than average, and the Little Ice Age, when it was colder than average. Each of these periods spans about 300 years, so we can expect 8-12 cycles within each. I will statistically compare the frequency, duration, and severity of SBW outbreaks between these contrasting climates, thereby gaining insight into the relationship of SBW population dynamics to climate. Another aspect of my research relates to the monarch butterfly, one of the few charismatic, iconic insects. To great consternation, its populations have been declining for the past 60 years. Why this is happening is an area of active research. But is this decline part of natural cycles? How unusual is this decline? Were populations perhaps smaller in general in pre-European times when there were fewer agricultural/disturbed fields that would support the monarch's host plant, milkweeds? I will core lakes within the main overwintering grounds of the monarch in Mexico where the highest concentrations of monarchs occur and use changes in the abundance of fossil wing scales as an index of past population sizes of monarchs.

东部云杉芽虫 (SBW) 是北美东部森林的主要干扰源，以 25-40 年为周期达到流行程度。这些疫情可能会造成严重的经济影响； 1967-1993 年的 SBW 爆发影响了北美东部 5000 万公顷的森林，估计每年损失 4400 万立方米木材。经济模型显示，加拿大大西洋地区在疫情爆发期间可能损失 10.8 至 153 亿加元。干扰通常根据其范围、严重程度、持续时间和频率进行分类。随着气候变暖继续改变世界范围内的景观，研究人员正试图了解和预测干扰的这些方面可能会如何变化，以及这些变化如何可能需要改变森林管理实践。了解飞蛾爆发与气候之间过去的关系将揭示未来爆发的变化，并使我们能够采取适当的管理策略。不幸的是，气候变化对 SBW 爆发频率、持续时间和严重程度的影响在很大程度上尚不清楚，主要是因为 1) 由于时间较长，仅对两次爆发进行了详细研究；2) SBW 与其宿主、捕食者、寄生虫和气候的相互作用极其复杂且很大程度上未知。拟议研究计划的目标之一是确定 SBW 爆发的频率、持续时间和严重程度与气候的关系。我们将使用一种新方法来研究过去的蛾类种群。飞蛾和蝴蝶的翅膀上覆盖着不同形状和大小的微观鳞片，这些鳞片由甲壳素制成，在湖泊沉积物中保存完好。我将根据两个截然不同的气候时期的湖泊沉积物重建 SBW 的爆发历史 - 中世纪气候异常（也称为中世纪温暖期），当时比平均温度更高，而小冰河时期，当时比平均温度更冷。每个时期的跨度约为 300 年，因此我们可以预期每个时期有 8-12 个周期。我将统计比较这些对比气候之间 SBW 爆发的频率、持续时间和严重程度，从而深入了解 SBW 种群动态与气候的关系。 我研究的另一个方面与帝王蝶有关，它是少数有魅力的标志性昆虫之一。令人震惊的是，过去 60 年来其人口一直在下降。为什么会发生这种情况是一个活跃的研究领域。但这种衰退是自然循环的一部分吗？这种下降有多不寻常？在前欧洲时代，能够支持帝王蝶寄主植物马利筋的农业/受干扰的田地较少，种群数量是否总体上可能较小？我将对墨西哥帝王蝶的主要越冬地内的湖泊进行取芯，那里是帝王蝶最集中的地方，并利用化石翼鳞丰度的变化作为帝王蝶过去种群规模的指标。