Figure 1.

Sampling design and comparative framework for saltmarsh and upland sparrow groups. (A) Conceptual framework depicting the direction of phenotypic divergence between saltmarsh birds and their closest upland relatives (illustrations by Jillian Ditner 2019). (B) Range map depicts distribution of the four species: savannah sparrows (blue), Nelson's sparrows (green), song sparrows (red), and swamp sparrows (purple). Sampling locations for salt marsh (squares) and upland (circles) populations are included and correspond to the species colors described above.