Department of Biology, Centre for Biodiversity Dynamics, NTNU, Trondheim, Norway.
Norwegian Institute for Nature Research, NINA, Tromsø, Norway.
Sci Rep. 2023 Sep 13;13(1):15181. doi: 10.1038/s41598-023-41940-6.
Demographic consequences of rapid environmental change and extreme climatic events (ECEs) can cascade across trophic levels with evolutionary implications that have rarely been explored. Here, we show how an ECE in high Arctic Svalbard triggered a trophic chain reaction, directly or indirectly affecting the demography of both overwintering and migratory vertebrates, ultimately inducing a shift in density-dependent phenotypic selection in migratory geese. A record-breaking rain-on-snow event and ice-locked pastures led to reindeer mass starvation and a population crash, followed by a period of low mortality and population recovery. This caused lagged, long-lasting reductions in reindeer carrion numbers and resultant low abundances of Arctic foxes, a scavenger on reindeer and predator of migratory birds. The associated decrease in Arctic fox predation of goose offspring allowed for a rapid increase in barnacle goose densities. As expected according to r- and K-selection theory, the goose body condition (affecting reproduction and post-fledging survival) maximising Malthusian fitness increased with this shift in population density. Thus, the winter ECE acting on reindeer and their scavenger, the Arctic fox, indirectly selected for higher body condition in migratory geese. This high Arctic study provides rare empirical evidence of links between ECEs, community dynamics and evolution, with implications for our understanding of indirect eco-evolutionary impacts of global change.
快速的环境变化和极端气候事件（ECEs）的人口统计学后果可能会在营养级上级联，具有进化意义，但很少被探索。在这里，我们展示了高北极斯瓦尔巴德的一次 ECE 如何引发食物链反应，直接或间接地影响越冬和迁徙脊椎动物的人口统计学，最终导致迁徙鹅的密度依赖表型选择发生转变。破纪录的雨夹雪事件和被冰封锁的牧场导致驯鹿大规模饥饿和种群崩溃，随后是一段时间的低死亡率和种群恢复。这导致驯鹿腐肉数量滞后且持续减少，结果北极狐的数量减少，北极狐是驯鹿的食腐动物和候鸟的捕食者。北极狐捕食鹅后代的减少使得大斑头雁的密度迅速增加。根据 r- 和 K-选择理论，预计随着种群密度的这种变化，最大限度地提高马尔萨斯适合度的鹅的身体状况（影响繁殖和离巢后存活）会增加。因此，冬季 ECE 对驯鹿及其食腐动物北极狐的作用，间接地选择了迁徙鹅的更高身体状况。这项高北极研究提供了 ECEs、群落动态和进化之间联系的罕见实证证据，对我们理解全球变化对间接生态进化影响具有重要意义。
