The balance between intrinsic and ecological fitness reveals hidden regimes in eco-evolutionary population dynamics

The balance between intrinsic and ecological fitness reveals hidden regimes in eco-evolutionary population dynamics | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article The balance between intrinsic and ecological fitness reveals hidden regimes in eco-evolutionary population dynamics Jacob Scott, Michael Hinczewski, Rowan Barker-Clarke, Jason Gray, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7403028/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Understanding how populations evolve requires accounting for both intrinsic fitness, defined by genotype and environment, and ecological interactions that emerge in mixed communities. While evolutionary experiments typically assess fitness in isolation, such monoculture measures may misrepresent dynamics in realistic, interacting populations. Here, we present a game-theoretic framework that explicitly separates intrinsic and ecological contributions to fitness, allowing us to map how ecological interactions can mask, mirror, maintain, or mimic selection driven by genetic differences. We derive analytical conditions for these regimes using deterministic replicator dynamics and validate them in stochastic Wright-Fisher models with mutation and drift. Applying our model to published microbial and cancer co-culture data, we show that real systems span both intrinsic-dominant and ecology-dominant regimes, with ecological effects sometimes reversing or neutralizing intrinsic fitness advantages. These results expose a critical blind spot in experimental design and interpretation, emphasizing the need to account for ecological interactions when inferring evolutionary dynamics and designing therapeutic strategies. Biological sciences/Ecology/Evolutionary ecology Biological sciences/Systems biology/Population dynamics Biological sciences/Evolution/Evolutionary theory Biological sciences/Evolution/Coevolution Biological sciences/Microbiology/Microbial communities/Microbial ecology Full Text Additional Declarations There is NO Competing Interest. Supplementary Files MMMM2025RewriteSI.pdf Supplementary Information, Figures, and Derivations Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7403028","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":510809568,"identity":"f2c09dc1-00a9-4f74-97b2-6c076fdb1138","order_by":0,"name":"Jacob 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