98-13 The Evolution of Power and Efficiency Across Temporal and Spatial Gradients

Session: Linking Biodiversity Loss to Environmental Stressors Through Integrated Approaches

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Abstract:

Energy is the currency that organisms invest in survival, growth, and reproduction. It follows, then, that how organisms obtain and expend energy, and how this varies across time and space, has major implications for their evolutionary success. The fossil record of marine ecosystems shows general trends of increased biomass coupled with a shift towards more active ecologies and increased energy flow through the entire ecosystem over the course of the Phanerozoic. This is reflected in changes in the composition of marine ecosystems through time, with modern shallow marine environments dominated by active, powerful, but energetically wasteful taxa, while more energetically efficient groups like crinoids and brachiopods that were once highly abundant are generally relegated to less productive, low energy, deep-water environments. In the terrestrial realm, analyses of net primary productivity (NPP) along an elevational gradient in a subtropical forest by Harris et al. (2013) found that gross primary productivity (GPP) is maximized at lower elevations, while efficiency (NPP/GPP) is maximized at higher elevations. Net primary productivity is subsequently at its highest at intermediate elevations, determined by the optimal tradeoff between gross primary productivity and efficiency. We hypothesize that similar tradeoffs should be present across all manner of spatiotemporal gradients, from water depth to geologic time. Given limiting factors such as availability of light, water, nutrients, space, etc., along a given gradient, selection should favor efficiency in gaining and expending energy at one end of the gradient, and high energy flux (power) at the cost of efficiency at the other end. Here, we explore this supposition with the aim of better understanding the dynamics of energy flow through ecosystems and their evolutionary implications.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8209

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