## Problem 171 — rank:161

**Title:** Migration–selection balance in heterogeneous landscapes

**Added binding assumptions (LaTeX):**

```latex
Assume enough regularity and strictly positive bounded resident density for $\nabla\log n$ and the elliptic operator to be defined. Specify the no-flux condition for the underlying allele-count process and its translated frequency boundary condition. Define stability in a chosen function space and separate invasion of each boundary monomorphism from persistence of an interior cline. Demographic noise remains spatially regularized at the declared scale.
```

**Direct edits:** 0. **Fresh external checks:** None; supplied sources retained as provenance.