Global warming increases latitudinal divergence in flowering dates of a perennial herb in humid regions across eastern Asia

摘要

Latitudinal patterns can reveal important ecological processes. The temporal overlap and divergence in flowering along latitudinal gradients is tightly related to intraspecific gene flow and interspecific interactions. Recent studies have predicted that global warming has led to more uniform spring and summer plant phenology across latitudes, but direct evidence is limited. Here, we test changes in the latitudinal pattern of peak flowering of a perennial herb Spiranthes sinensis (Orchidaceae) during 1901-2017 across similar to 40 degrees of latitude in eastern Asia, spanning humid to water-limited regions. We found that flowering phenology did not vary significantly across latitudes in water-limited regions. However, global warming has significantly increased temporal divergence in flowering phenology across latitudes in humid regions-each 1 degrees C warming in mean annual temperature leads to an increased divergence of 2.47 days across 1 degrees of latitude. Significantly stronger temperature sensitivity at lower latitudes is likely responsible for the increased phenological divergence. Additionally, we found that the phenological divergence is larger at lower latitudes in humid regions. These findings provide empirical evidence of variation in the latitudinal phenology shift at longer temporal and larger spatial scales under climate change, and highlight its potential role in ecosystem functioning, such as intraspecific gene flow and interspecific interaction.