Urbanization can compromise biodiversity as cities expand further into native landscapes. The urban heat island (UHI) describes elevated urban temperatures due to heat retained by built structures (e.g. concrete surfaces). Animal behavior may be critical in determining an animal’s ability to thrive in the wake of human disturbance. Yet, we have a relatively poor understanding of how animal behavior is affected by the UHI. We examined sibling cannibalism in urban and desert juvenile black widow spiderling (Latrodectus hesperus) lineages exposed to extreme UHI temperatures (33 °C) or native Sonoran desert temperatures (27 °C). Family of origin had a significant impact on cannibalism, while the effects of temperature and habitat were dependent on spiderling density. Our most pronounced results came at the lower densities of three and two spiderlings. Here habitat and temperature interacted such that spiderlings at 33 °C were consistently more cannibalistic than spiderlings at 27 °C, and this result was consistently stronger for spiderlings from urban families than it was for spiders from desert families. If UHI-induced siblicide promotes the survival and growth of a subset of spiderlings from a clutch, then it might actually foster urban population growth. In contrast, if siblicide in the city simply reduces clutch size, then we might expect the UHI to slow urban infestations. Understanding behavioral phenotypes underlying the explosive population growth of urban pest species will aid in the development of safer and more effective deterrents to infestations, and allow us to better understand the mechanisms shaping urban biodiversity patterns.

随着城市进一步扩展到本土景观，城市化可能会损害生物多样性。城市热岛 (UHI) 描述了由于建筑结构（例如混凝土表面）保留的热量而导致的城市温度升高。动物行为对于确定动物在人类干扰后茁壮成长的能力可能至关重要。然而，我们对 UHI 如何影响动物行为的了解相对较少。我们研究了城市和沙漠幼年黑寡妇蜘蛛（Latrodectus hesperus) 暴露于极端 UHI 温度 (33 °C) 或当地索诺兰沙漠温度 (27 °C) 的谱系。原生家庭对同类相食有显着影响，而温度和栖息地的影响则取决于蜘蛛密度。我们最显着的结果出现在密度较低的三只和两只小蜘蛛。在这里，栖息地和温度相互作用，因此 33 °C 下的蜘蛛比 27 °C 下的蜘蛛更容易自相残杀，而且城市家庭的蜘蛛的这种结果始终比沙漠家庭的蜘蛛更强。如果 UHI 诱导的杀同胞促进了一窝小蜘蛛的生存和生长，那么它实际上可能会促进城市人口的增长。相比之下，如果城市中的兄弟姐妹只是减少了离合器的尺寸，那么我们可能会期望 UHI 减缓城市侵扰。了解城市害虫种群爆炸性增长背后的行为表型将有助于开发更安全、更有效的虫害威慑，并使我们能够更好地了解塑造城市生物多样性模式的机制。