Evolution takes multiple paths to evolvability when facing environmental change
Bhaskar Kumawat, Alexander Lalejini, Monica M. Acosta, and Luis Zaman
Authors Info & Affiliations
Edited by Paul Turner, Yale University, New Haven, CT; received July 14, 2024; accepted November 27, 2024
December 31, 2024
122 (1) e2413930121
https://doi.org/10.1073/pnas.2413930121
Significance
That all the diversity of life constitutes what Erasmus Darwin called “a single living filament”—an unbroken chain of descent from the last universal common ancestor—is evidence of life’s fundamental adaptability. However, the evolutionary processes that shape this ability to adapt (evolvability) remain elusive because of the required resolution and timespan of observations. Using evolving, self-replicating computer programs, we find that multiple pathways to increased evolvability emerge concurrently and distinctly aid adaptation. One pathway (evolved mutational landscapes) allows rapid adaptation to previously seen environments, while the other (higher mutation rates) allows rapid adaptation to entirely new environments. This multifaceted picture of evolvability helps us understand how organisms deal with ever-changing conditions and relentlessly explore nature’s opportunities for innovation.
Abstract
Life at all scales is surprisingly effective at exploiting new opportunities, as demonstrated by the rapid emergence of antimicrobial resistance and novel pathogens. How populations acquire this level of evolvability and the various ways it aids survival are major open questions with direct implications for human health. Here, we use digital evolution to show that changing environments facilitate the simultaneous evolution of high mutation rates and a distribution of mutational effects skewed toward beneficial phenotypes. The evolved mutational neighborhoods allow rapid adaptation to previously encountered environments, whereas higher mutation rates aid adaptation to completely new environmental conditions. By precisely tracking evolving lineages and the phenotypes of their mutants, we show that evolving populations localize on phenotypic boundaries between distinct regions of genotype space. Our results demonstrate how evolution shapes multiple determinants of evolvability concurrently, fine-tuning a population’s adaptive responses to unpredictable or recurrent environmental shifts.
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