Hagen, S. B.

Spatial synchrony, correlated population dynamics across space, is a defining feature of ecological dynamics, shaping outbreaks, cycles, and waves across ecosystems. Yet its genetic consequences remain poorly resolved because classical population-genetic models assume demographic independence and equilibrium conditions that synchronised populations systematically violate. Here I introduce Synchrony Genetics, a general framework that treats ecological coupling as the causal process and spatial synchrony as only one observable manifestation of that coupling. The framework links the three canonical ecological coupling mechanisms, environmental (Moran-type) coupling, dispersal-driven coupling, interaction-mediated coupling, alone or in combination, to their characteristic genetic signatures. Under this view, genetic structure is not a static property of populations or a proxy for equilibrium connectivity, but an emergent indicator of how populations are ecologically coupled across space. These expectations are synthesised in a Prediction Matrix that maps coupling mechanisms to diagnostic contrasts across widely used genetic metrics, enabling mechanism attribution from genetic data alone or in combination with demographic information. By reframing genetic patterns as evidence of coupling mechanisms rather than equilibrium processes, Synchrony Genetics provides a mechanistic foundation for interpreting genetic data in spatially coherent systems where dispersal, demographic covariance, and ecological interactions jointly shape genetic signatures. More broadly, the framework establishes a new baseline for genetic inference in systems where ecological coupling violates demographic independence, repositioning genetic structure as mechanistic evidence of how populations are linked across space.