Dorian Nicholas N, McCarthy Max W, Crone Elizabeth E
Department of Biology, Tufts University, Medford, Massachusetts, USA.
Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, USA.
J Anim Ecol. 2023 Feb;92(2):285-296. doi: 10.1111/1365-2656.13778. Epub 2022 Aug 2.
Across taxa, the timing of life-history events (phenology) is changing in response to warming temperatures. However, little is known about drivers of variation in phenological trends among species. We analysed 168 years of museum specimen and sighting data to evaluate the patterns of phenological change in 70 species of solitary bees that varied in three ecological traits: diet breadth (generalist or specialist), seasonality (spring, summer or fall) and nesting location (above-ground or below-ground). We estimated changes in onset, median, end and duration of each bee species' annual activity (flight duration) using quantile regression. To determine whether ecological traits could explain phenological trends, we compared average trends across species groups that differed in a single trait. We expected that specialist bees would be constrained by their host plants' phenology and would show weaker phenological change than generalist species. We expected phenological advances in spring and delays in summer and fall. Lastly, we expected stronger shifts in above-ground versus below-ground nesters. Across all species, solitary bees have advanced their phenology by 0.43 days/decade. Since 1970, this advancement has increased fourfold to 1.62 days/decade. Solitary bees have also lengthened their flight period by 0.44 days/decade. Seasonality and nesting location explained variation in trends among species. Spring- and summer-active bees tended to advance their phenology, whereas fall-active bees tended to delay. Above-ground nesting species experienced stronger advances than below-ground nesting bees in spring; however, the opposite was true in summer. Diet breadth was not associated with patterns of phenological change. Our study has two key implications. First, an increasing activity period of bees across the flight season means that bee communities will potentially provide pollination services for a longer period of time during the year. And, since phenological trends in solitary bees can be explained by some ecological traits, our study provides insight into mechanisms underpinning population viability of insect pollinators in a changing world.
在不同的生物分类群中，生命史事件（物候）的时间正在随着气温升高而发生变化。然而，对于物种间物候趋势变化的驱动因素，我们却知之甚少。我们分析了 168 年的博物馆标本和观测数据，以评估 70 种独居蜂的物候变化模式，这些独居蜂在三个生态特征上存在差异：食性广度（广食性或狭食性）、季节性（春季、夏季或秋季）和筑巢位置（地上或地下）。我们使用分位数回归估计了每种蜜蜂年度活动（飞行持续时间）的开始、中位数、结束和持续时间的变化。为了确定生态特征是否能够解释物候趋势，我们比较了在单一特征上存在差异的物种组的平均趋势。我们预计狭食性蜜蜂会受到其寄主植物物候的限制，并且与广食性物种相比，其物候变化会更弱。我们预计春季物候提前，夏季和秋季物候延迟。最后，我们预计地上筑巢的蜜蜂与地下筑巢的蜜蜂相比，物候变化会更强烈。在所有物种中，独居蜂的物候每十年提前了 0.43 天。自 1970 年以来，这种提前幅度增加了四倍，达到每十年 1.62 天。独居蜂的飞行期也每十年延长了 0.44 天。季节性和筑巢位置解释了物种间趋势的变化。春季和夏季活动的蜜蜂往往物候提前，而秋季活动的蜜蜂往往物候延迟。春季，地上筑巢的物种比地下筑巢的蜜蜂物候提前更强烈；然而，夏季情况则相反。食性广度与物候变化模式无关。我们的研究有两个关键意义。首先，整个飞行季节蜜蜂活动期的增加意味着蜜蜂群落可能在一年中更长的时间内提供授粉服务。而且，由于独居蜂的物候趋势可以由一些生态特征来解释，我们的研究为不断变化的世界中昆虫传粉者种群生存能力的潜在机制提供了见解。
