 Balancing selection of the sort observed by Ford leaves its own unique “reverse” footprint on neutral diversity (Kreitman &amp; Di Rienzo 2004) . Because the segments of DNA constituting the balanced polymorphism are held in the population by selection much longer than expected based on random drift, these segments have a higher effective population size (owing to lower variation in offspring numbers than random). As a result, they have a longer time to accumulate mutational variation at nearby neutral sites. In some cases, the time is longer than that required to create new species, resulting in trans-specific polymorphisms (Cho et al. 2006). Thus, levels of neutral diversity are expected to be enhanced in the vicinity of a molecular balanced polymorphism. When the mating system restricts recombination (e.g., selfing or inbreeding species), the region of elevated neutral diversity in the vicinity of a balanced polymorphism can be extensive (e.g., Arabiodopsis thaliana [Tian et al. 2002]).