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

Discussion Temperature and precipitation have a mix of positive and negative effects on D. alaskana vital rates, consistent with a variety of other studies. Our findings of positive temperature effects on survival and growth, but negative temperature effects on reproduction, are similar to results found in other alpine plants. Doak and Morris [26] found that higher temperature decreases reproduction in the wide-ranging alpine plants Silene acaulis and Polygonum viviparum, but increases growth rates, perhaps due to longer and warmer growing seasons. In D. alaskana, we also see a lagged negative effect of coldest month temperature on survival, which is surprising given that coldest month temperature reduces the probability of fruiting, which should in turn increase survival given the plant’s semelparity. Precipitation also impacts vital rates, with a mix of positive and negative effects. Positive effects of precipitation could reflect increased water availability or protection from damaging frosts due to high snowpack [27–29]. Alternatively, a Fig 8. Δλc, the effect of each climate variable on the change in population growth rate. We show Δλc, calculated for each climate variable changing current (2008–2022) climate variables to future (2084–2099) climate variables, one climate variable at a time. Bars indicate the mean Δλc and error bars indicate the 95% confidence intervals of Δλcs, calculated across bootstrapped parameter estimates. Horizontal lines indicate the mean Δλ, future-

current population growth rate, and dotted lines indicate the 95% confidence intervals of Δλ, calculated across bootstrapped parameter estimates. In both panels, populations are arranged in the same order as in prior figures (increasing current average annual temperature). https://doi.org/10.1371/journal.pone.0247290.g008 PLOS ONE Nonlinear responses of population growth rate to climate change PLOS ONE | https://doi.org/10.1371/journal.pone.0247290 March 3, 2021 14 / 20