Chick Lacy D, Strickler Stephanie A, Perez Abe, Martin Ryan A, Diamond Sarah E
Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA.
School of Biological Sciences, Illinois State University, Normal, IL 61790, USA.
J Therm Biol. 2019 Feb;80:119-125. doi: 10.1016/j.jtherbio.2019.01.004. Epub 2019 Jan 11.
For many species, the timing of life cycle events is advancing under contemporary global climate change. However, much less is known regarding phenological shifts as a result of other sources of anthropogenic change, such as urban warming. In both cases, progress has been hampered by a focus on phenological traits such as the timing of emergence, rather than the phenology of more directly related fitness traits such as the timing of reproduction. Here we explore how urban heat island effects shape the timing of reproduction in an acorn-dwelling ant. We used a common garden experiment with acorn ants collected from three cities in the eastern United States along a latitudinal gradient and reared long-term in the laboratory under five temperature treatments. This allowed us to quantify the effects of temperature on reproductive phenology across three scales-a biogeographic temperature cline, three urban vs. rural temperature comparisons, and five laboratory rearing temperatures. At our northernmost and southernmost cities (spanning 6° of latitude), we found both urbanization and warmer laboratory rearing temperature significantly advanced reproductive phenology; ants from the lowest latitude city also had earlier reproductive phenology compared with the higher latitude cities. In the field, the differences in urban versus rural acorn ant reproductive phenology translate to approximately one month earlier reproduction in the urban populations. For insects with synchronous mating events, such as ants, shifts in the already short window of time to reproduce could limit mating across environments, potentially leading to reproductive isolation between urban and rural populations.
对于许多物种而言，在当代全球气候变化的背景下，其生命周期事件的发生时间正在提前。然而，对于诸如城市变暖等其他人为变化源所导致的物候变化，我们所知甚少。在这两种情况下，由于研究重点都放在诸如出现时间等物候特征上，而非像繁殖时间等更直接相关的适合度特征的物候上，进展受到了阻碍。在此，我们探究城市热岛效应如何影响橡果蚁的繁殖时间。我们进行了一项共同花园实验，使用从美国东部沿纬度梯度的三个城市采集的橡果蚁，并在实验室中于五种温度处理下长期饲养。这使我们能够在三个尺度上量化温度对繁殖物候的影响——生物地理温度梯度、三个城市与农村温度的比较以及五种实验室饲养温度。在我们最北部和最南部的城市（跨越6个纬度），我们发现城市化和更高的实验室饲养温度均显著提前了繁殖物候；来自最低纬度城市的蚂蚁与更高纬度城市的蚂蚁相比，繁殖物候也更早。在野外，城市与农村橡果蚁繁殖物候的差异导致城市种群的繁殖时间提前了约一个月。对于具有同步交配事件的昆虫，如蚂蚁，已经很短的繁殖时间窗口的变化可能会限制不同环境之间的交配，潜在地导致城市和农村种群之间的生殖隔离。
