Long-term responses of life-history strategies to climatic variability in flowering plants

Abstract

SummaryThe evolution of annual or perennial strategies in flowering plants may depend on a broad array of temperature and precipitation variables. Previously documented correlations between life history strategy and climate appear to be clade-specific and fail to consider the coevolution of climatic niches and life history strategies.Here we combine annual and perennial life history data with geographic distribution for 9,939 flowering plant species and utilize a recently developed method that accounts for the joint evolution of continuous and discrete traits to evaluate two hypotheses: (1) annuals tend to evolve in highly seasonal regions prone to extreme heat and drought, and (2) annuals tend to have faster rates of climatic niche evolution than perennials.We find temperature, particularly the maximum temperature of the warmest month, is the most consistent climatic factor influencing life history evolution in flowering plants. Unexpectedly, we find that the rates of climatic niche evolution are faster in perennials than in annual lineages.We propose that annuals are consistently favored in areas prone to extreme heat due to their ability to escape heat stress as seeds, but they tend to be outcompeted by perennials in regions where extreme heat is uncommon or nonexistent.