Evolutionary consequences of dispersal ability in cactus - feeding insects 3 4

13 Although gene flow is an important determinant of evolutionary change, the role of ecological factors such 14 as specialization in determining migration and gene flow has rarely been explored empirically. To examine 15 the consequences of dispersal ability and habitat patchiness on gene flow, migration rates were compared in 16 three cactophagous Longhorn beetles using coalescent analyses of mtDNA sequences. Analyses of 17 covariance were used to identify the roles of dispersal ability and habitat distribution in determining 18 migration patterns. Dispersal ability was a highly significant predictor of gene flow (p<0.001), and was 19 more important than any other factor. These findings predict that dispersal ability may be an import factor 20 shaping both microevolutionary and macroevolutionary patterns; this prediction is borne out by 21 comparisons of species diversity in cactus-feeding groups. 22