Department of Biology, University of Washington, Seattle, WA, USA.
Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA.
J Anim Ecol. 2021 May;90(5):1252-1263. doi: 10.1111/1365-2656.13451. Epub 2021 Mar 12.
Species with different life histories and communities that vary in their seasonal constraints tend to shift their phenology (seasonal timing) differentially in response to climate warming. We investigate how these variable phenological shifts aggregate to influence phenological overlap within communities. Phenological advancements of later season species and extended durations of early season species may increase phenological overlap, with implications for species' interactions such as resource competition. We leverage extensive historic (1958-1960) and recent (2006-2015) weekly survey data for communities of grasshoppers along a montane elevation gradient to assess the impact of climate on shifts in the phenology and abundance distributions of species. We then examine how these responses are influenced by the seasonal timing of species and elevation, and how in aggregate they influence degrees of phenological overlap within communities. In warmer years, abundance distributions shift earlier in the season and become broader. Total abundance responds variably among species and we do not detect a significant response across species. Shifts in abundance distributions are not strongly shaped by species' seasonal timing or sites of variable elevations. The area of phenological overlap increases in warmer years due to shifts in the relative seasonal timing of compared species. Species that overwinter as nymphs increasingly overlap with later season species that advance their phenology. The days of phenological overlap also increase in warm years but the response varies across sites of variable elevation. Our phenological overlap metric based on comparing single events-the dates of peak abundance-does not shift significantly with warming. Phenological shifts are more complex than shifts in single dates such as first occurrence. As abundance distributions shift earlier and become broader in warm years, phenological overlap increases. Our analysis suggests that overall grasshopper abundance is relatively robust to climate and associated phenological shifts but we find that increased overlap can decrease abundance, potentially by strengthening species interactions such as resource competition.
具有不同生活史和社区的物种，其季节性限制各不相同，往往会根据气候变暖而不同地改变其物候（季节性时间）。我们研究这些可变的物候变化如何聚集在一起，影响社区内的物候重叠。后期季节物种的物候提前和早期季节物种持续时间的延长可能会增加物候重叠，这对物种之间的相互作用（如资源竞争）产生影响。我们利用广泛的历史（1958-1960 年）和近期（2006-2015 年）在高山海拔梯度上的蚱蜢群落每周调查数据，评估气候对物种物候和丰度分布变化的影响。然后，我们研究这些响应如何受到物种和海拔季节性时间的影响，以及它们如何在总体上影响群落内物候重叠的程度。在温暖的年份，丰度分布更早地进入季节并变得更加广泛。物种之间的总丰度响应变化不定，我们没有检测到物种之间的显著响应。丰度分布的变化并没有受到物种季节性时间或不同海拔地点的强烈影响。由于比较物种的相对季节性时间的变化，物候重叠区域在温暖的年份增加。以若虫越冬的物种与物候提前的后期季节物种重叠越来越多。在温暖的年份，物候重叠的天数也会增加，但响应因不同海拔的地点而异。我们基于比较单一事件（峰值丰度日期）的物候重叠度量不会随着变暖而显著变化。物候变化比单一日期（如首次出现）的变化更为复杂。随着温暖年份丰度分布更早和更广泛，物候重叠增加。我们的分析表明，整体蚱蜢丰度对气候和相关物候变化相对稳健，但我们发现，重叠增加会降低丰度，可能通过加强资源竞争等物种相互作用来实现。
