Simple traits predict complex temperature responses across scales

Abstract

Microbial communities regulate ecosystem responses to climate change. But predicting these responses is challenging due to complex interactions among processes at multiple ecological scales. Organismal traits that determine individual performance and ecological interactions are essential for scaling up predictions of environmental responses from individuals to ecosystems. We combine experiments and mathematical models to show that key microbial traits—cell size, shape, and cell contents—independently drive shifts in demographic rates across temperatures, having cascading effects on community structure, dynamics, and ecosystem function. Moreover, intra- and interspecific trait variation play distinct, trait-specific roles in temperature responses. These species-level responses scale up to cause predictable, nonlinear shifts in microbial community composition and respiration rates, with direct implications for the effects of warming on the global carbon cycle. Mechanistically linking microbes with climate using traits will help refine predictions about complex ecosystem-climate feedbacks and the pace of climate change.

Feedbacks between size and density determine rapid eco-phenotypic dynamics

“…To assess whether observed changes in body size were more likely due to plasticity or rapid evolution, we fitted two possible models that track change in the abundance and average body size of a population, N, as it grows logistically towards a carrying capacity K with intrinsic growth rate r. Following previous work (Abrams 1977;Abreu et al 2019;Lax, Abreu & Gore 2020;Wieczynski et al 2021), we included an additional mortality term in the ecological dynamics, ! ", to account for regular loss of individuals from the population (through sampling).…”

“…In protists, we expect changes in body size to be at least partly caused by plasticity because reproduction (cell division) is tightly linked to ontogenetic changes in body size (cells grow then divide when a critical size is attained). However, T. pyriformis also reproduces extremely fast (4+ generations per day) and exhibits wide standing variation in body size (Wieczynski et al 2021), so rapid evolutionary change is also possible. Therefore, to address our second question, we compare two alternative mathematical models: one that assumes only plasticity drives change in body size (plasticity model), and one that assumes only rapid evolution drives change in body size (eco-evolutionary model).…”

Characterization of Dry-Season Phenology in Tropical Forests by Reconstructing Cloud-Free Landsat Time Series

“…Soil nitrogen and phosphorus also affect tropical forest functional traits [20,21]. Second, tree competition for light in models of forest dynamics, and related carbon cycling, is typically modeled at 15 to 20-m spatial scales [22][23][24]. Third, satellite imagery with fine spatial resolution should mitigate uncertainties in phenology detection.…”

Temperature and nutrients drive eco-phenotypic dynamics in a microbial food web

“…Additionally, temperature and nutrients can interactively affect body size, where body size may increase with nutrients at low temperature but decrease at high temperature (Tabi et al 2019). Although body size is often considered a response variable, its strong influences on population growth (Fenchel 1974;Savage et al 2004) and species interactions (Ferenc & Sheppard 2020) mean that rapid phenotypic responses to temperature, nutrients, or both, may have consequences for food web structure and dynamics in warmer climates (Brose et al 2012;Bernhardt et al 2018;Wieczynski et al 2021). However, whether body size only responds to environmental conditions, whether rapid changes in body size influences how environmental conditions affect food webs, or whether shifts in body size in a species can influence body size responses to environmental conditions in the species they interact with, are not well understood.…”