Figure 3.
Under the same degree of environmental variability, time series with more short-term variation favour species coexistence. Here, we fix the sum of long- and short-term variation (σlong − 0.5)2 + (σshort − 0.5)2 = 400 and examine the fluctuations with different combinations of the two time scales of environmental variation. Specifically, we analyse the temperature time series and the probability of three population-dynamic outcomes: species 1 dominates (p1), species 2 dominates (p2) and species coexistence, (pco). (a) The temperature time series when most of the variation occurs as long-term variation (σlong = 20.5, σshort = 0.5) and thermal performance curves of the two species. (b,c) Autocorrelation function and windowed averages of the temperature time series. (d) The population dynamics corresponding to (a) and the probabilities of coexistence or when a single species dominates. (e–t) The same analyses for another four variation settings where short-term variation increases, but long-term variation decreases. Note that we can only keep the total variance approximately constant. In other words, the difference in variances in the parameter space is marginal, but the variance is not actually constant. (Online version in colour.)