A Constructal Law interpretation of species variability: Insights from microalgae

The Constructal Law provides a physical perspective for interpreting evolutionary change as a continuous reorganization of structures that facilitate the flow of energy, matter, and information. In living systems, these flows are inherently coupled, as cellular responses to environmental change depend on the integration of metabolic processes with regulatory and informational networks. Microalgae, with short generation times and diverse evolutionary lineages, are ideal models to explore this principle. This study reanalyzes three previously published experimental investigations on eukaryotic microalgae: the diatom Phaeodactylum tricornutum (Stramenopiles), the coccolithophore Emiliania huxleyi (Haptophytes), and Picochlorum species (Archaeplastida). Their reported evolutionary, physiological, metabolic, morphological, and genomic responses are interpreted through the lens of constructal design. In P. tricornutum, adaptation to elevated CO₂ and warming involved coordinated reorganization of metabolic pathways, including respiration, the tricarboxylic acid cycle, lipid metabolism, and protein ubiquitination, reflecting internal configurations that enhance the flow of carbon, energy, electrons, and the regulatory information that coordinates these processes. E. huxleyi displayed complex, sometimes reversible, changes in cell size and calcification under long-term acidification, illustrating trade-offs in energy and material flow. In Picochlorum, genomic plasticity, gene gain and loss, allelic diversity, and horizontal gene transfer provided alternative routes for metabolic flux, demonstrating the genome as a flow-oriented network. Across these phylogenetically distant taxa, adaptive responses show that evolutionary processes can be understood as the reorganization of internal and external flows, consistent with the Constructal Law. This integrative perspective links biological natural selection to physical principles, offering a novel framework for interpreting species variability and adaptive potential in microalgae and beyond.