Fig 3. Genetic differentiation tends to correlate with infection difference in parapatry.

Magnitude of genetic differentiation, F_ST and F_ST residual from geographic distance, in relation to proportional difference in parasite species composition and difference in parasite abundance in parapatric lake-stream pairs (panels A and B) and in allopatric population combinations (panels C and D) of threespine stickleback (Gasterosteus aculeatus) from four lake systems (Wohlen, Biel, Constance and Geneva) in Switzerland. Symbols refer to different population combinations: parapatric lake-stream pairs (dots); allopatric lake-lake pairs (diamonds), stream-stream pairs (squares) and lake-stream pairs (triangles). Fitted lines represent linear regressions to indicate the slope and intercept of the relationships.