Tue, Aug 16, 2022: 10:30 AM-10:45 AM
513F
Background/Question/MethodsCommunity responses to environmental change are driven by population demography, which is in turn influenced by the phenotypic fit of individuals to their environment. The fitness landscape, which describes the relationship between multidimensional phenotypes and fitness, is a key determinant of evolution within species and can be extended to multispecies communities along environmental gradients. Knowing the contours of fitness landscapes would improve our understanding of how selection shapes ecological communities and permit mechanistic predictions of community dynamics in changing environments. However, the shape of fitness landscapes for multispecies communities is unknown because we have lacked a framework for estimating fitness across species and environments. Here we describe a framework to estimate multispecies fitness landscapes and apply it to trees in temperate forests across a climatic gradient in the eastern United States.
Results/ConclusionsFunctional traits influenced tree survival, growth, and recruitment rates, and these effects varied with tree size and mean annual temperature. Tree species with dense wood had high survival rates but grew slowly, especially as saplings and in cold environments, and produced relatively few recruits. Species with tall maximum height had high survival rates and grew quickly, especially at large sizes, but were slow to reach reproductive maturity. The effects of SLA on demographic rates were complex and varied with individual size, temperature, and wood density (i.e., trait-by-trait interations). By integrating trait effects on demographic performance across the life cycle, we estimated the net effect of traits on fitness, revealing the shapes of fitness landscapes. Fitness increased with maximum height at all temperatures, indicating that tall species had a competitive advantage in these mature, closed-canopy forests. Wood density and SLA had interactive effects on fitness, producing bimodal fitness landscapes that indicate the presence of alternative functional strategies. These results demonstrate the adaptive value of functional traits for trees across a climatic gradient. Our approach provides a pathway to generate mechanistic, general predictions of population and community dynamics in changing environments.
Results/ConclusionsFunctional traits influenced tree survival, growth, and recruitment rates, and these effects varied with tree size and mean annual temperature. Tree species with dense wood had high survival rates but grew slowly, especially as saplings and in cold environments, and produced relatively few recruits. Species with tall maximum height had high survival rates and grew quickly, especially at large sizes, but were slow to reach reproductive maturity. The effects of SLA on demographic rates were complex and varied with individual size, temperature, and wood density (i.e., trait-by-trait interations). By integrating trait effects on demographic performance across the life cycle, we estimated the net effect of traits on fitness, revealing the shapes of fitness landscapes. Fitness increased with maximum height at all temperatures, indicating that tall species had a competitive advantage in these mature, closed-canopy forests. Wood density and SLA had interactive effects on fitness, producing bimodal fitness landscapes that indicate the presence of alternative functional strategies. These results demonstrate the adaptive value of functional traits for trees across a climatic gradient. Our approach provides a pathway to generate mechanistic, general predictions of population and community dynamics in changing environments.