Category: Pop. Genetics

Summary: Finding the dormant-state coupling needed for a seed bank to bridge a modular fitness valley and spread the leading quasispecies mode from a source peak toward an escape region.

Quasispecies models describe mutation-selection balance on rugged fitness landscapes, while dormancy can buffer lineages against immediate selective loss. This experiment asks when dormant-state coupling becomes strong enough to bridge a deep modular fitness valley, turning a source-localized leading mode into a broader source-to-escape bridge.

The model constructs dense symmetric operators on a modular landscape with explicit source, valley, and escape regions, then uses iterative deepening with eigensolves to bisect the coupling threshold across larger systems. It records how much mass of the leading mode sits on the source, in the valley, and on the escape sector as the bridge forms.

That makes the result a threshold study of valley crossing through seed-bank buffering rather than through direct high-mutation exploration alone. The output is useful for seeing when dormancy changes the geometry of adaptation, not just its net growth rate.

Method: Dense symmetric eigensolves with iterative deepening and bisection on dormant-state bridge coupling lambda across N=64 to 2048.

What is measured: Critical bridge-coupling threshold, source mass, valley mass, escape mass, bridge ratio, participation ratio, leading eigenvalue, and bracket width.