Intraspecific variability may not compensate for increasing climatic volatility

Abstract

The role of intraspeciic variability is being examined to improve predictions of responses to climate change or invasions and in research on diversity. Simultaneously, the probability and implications of increased high-frequency climate variability have been raised. An agent based model simulated two species on an environmental gradient representing an alpine treeline; a trend in its volatility was added. The species have diferent levels of variability, and each individual has further unique heterogeneity. Environmental volatility and individual heterogeneity were based on tree ring data from Pinus albicaulis. Simulations show that increasing volatility leads to population declines, including extinctions, and to sharper ecotones, and this impact is only slightly lessened by higher heterogeneity. Some simulation runs reveal an unanticipated selection for greater individual variability when volatility creates strong negative anomalies that fall short of extinction events. Increasing volatility can have signiicant ecological impacts because negative anomalies are not balanced by positive ones.

Rapid changes in seed dispersal traits may modify plant responses to global change

“…Messer and Petrov 2013) variation. In general, such variation should improve the performance and adaptive potential of plants to environmental variation (see Malanson (2018) for a simulation study of the role of intraspecific variability and climatic volatility). Imbert and Ronce (2001) showed that heteromorphic Asteraceae increase the dispersal of their progeny under environmental stress by varying the relative proportion of wind- and animal-dispersed seed morphs.…”

Simulations reveal climate and legacy effects underlying regional beta diversity in alpine vegetation

“…For example, a global dataset would allow comparisons of multiple regions (e.g., Testolin et al, 2021), but further database developments are needed (e.g., to sPlot; Bruelheide et al, 2019) as are simulations with higher spatial and biological resolution. Better quantification of isolation, with recognition of past pathways as well as dispersal kernels, could define a gradient of isolation that could underlie differences in the processes determining plant community assembly (Saura et al, 2014), and the inclusion of more realistic response or fitness functions of species, with competition, facilitation, and intraspecific variation (e.g., Malanson, 2015Malanson, , 2018, would allow more rigorous tests of outcomes other than beta diversity.…”

“…We created virtual species with fitness representing geographic legacies or adaptation to climatic gradients, assuming that the former was useful for the purpose of comparison because a true null model was a weak strawman (substantiated preliminary analyses of a null model; cf. Malanson, 2018). We created a spatially explicit individual-based simulation with Monte Carlo reproduction, dispersal, and mortality in Netlogo (v6.1.1;Wilensky, 1999); Bauduin et al (2019) summarized the advantages of such simulations, which have a long history in alpine ecology (e.g., Humphries et al, 1996).…”