Climate change impacts on population growth across a species’ range differ due to nonlinear responses of populations to climate and variation in rates of climate change

month of the prior year increased current-year survival (Table 1, Fig 3A), which again can be explained by semelparity: higher precipitation in the prior year’s coldest month reduced the probability of fruiting in that year, which then increased survival in the current year. Counter- intuitively, while high temperature during the previous year’s coldest month also reduced the probability of fruiting in the previous year (which should increase survival), this temperature variable actually decreased survival in the current year (Table 1, Fig 3A). In addition, survival exhibited positive interactions between size and both temperature and precipitation in the coldest month of the prior year (Table 1). Finally, mean size next year was smaller when annual precipitation was higher, but greater when annual temperature was higher (Table 1, Fig 3B). Climate is predicted to be warmer and wetter in all populations on average, but the magni- tude of temperature increases and the timing of changes in precipitation differ among popula- tions (Fig 4). Mean annual temperature increase is projected to be higher in all populations by Fig 3. Effects of climate on vital rates. Vital rate relationships with climate for probability of survival (A), mean size after one year of growth (B), probability of fruiting (C), and number of fruits given fruiting (D) for a plant of median size (or for C, median size of fruiting plant). For A, we show how the impact of precipitation in the coldest month changes with coldest month conditions in the year prior. For prior year conditions, we use the

observed temperature and precipitation for the coldest, wettest, and warmest/ driest populations (coldest: -9˚ C, 56.0 mm, wettest: -7˚ C, 158.2 mm, warmest/ driest: 1˚ C, 54.4 mm). For B and C, we show how the impact of temperature varies with the associated precipitation during the same interval, using values of precipitation from the driest or wettest populations: B driest: 662.8 mm, B wettest: 1431 mm, C driest: 43.2 mm, C wettest: 180.8 mm. See Table 1 for all parameter estimates, and S1 Fig in S1 Appendix for raw data. https://doi.org/10.1371/journal.pone.0247290.g003 PLOS ONE Nonlinear responses of population growth rate to climate change PLOS ONE | https://doi.org/10.1371/journal.pone.0247290 March 3, 2021 9 / 20