Evolutionary consequences of dispersal ability in cactus-feeding insects

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