For pollinators to exert selection on floral traits, they must be able to detect and respond to differences in floral morphologies. I examined foraging preferences by the bee Apis mellifera (Apidae) visiting naturally occurring flowers of Mimulus guttatus (Scrophulariaceae). The results indicate that A. mellifera preferentially selects larger M. guttatus flowers in their foraging bouts. Since d...

BACKGROUND AND AIMS The genetic basis of leaf shape has long interested botanists because leaf shape varies extensively across the plant kingdom and this variation is probably adaptive. However, knowledge of the genetic architecture of leaf shape variation in natural populations remains limited. This study examined the genetic architecture of leaf shape diversification among three edaphic speci...

Understanding the process by which hybrid incompatibility alleles become established in natural populations remains a major challenge to evolutionary biology. Previously, we discovered a two-locus Dobzhansky-Muller incompatibility that causes severe hybrid male sterility between two inbred lines of the incompletely isolated wildflower species, Mimulus guttatus and M. nasutus. An interspecific c...

The evolutionary transition from outcrossing to self-fertilization has far-reaching implications for patterns of intraspecific genetic diversity and the potential for speciation. Using DNA sequence variation at two nuclear loci, we examined the divergence history of two closely related species of Mimulus. To investigate the effects of mating system and introgressive hybridization on the outcros...

Conspecific pollen precedence (CPP) is a major component of reproductive isolation between many flowering plant taxa and may reveal mechanisms of gametophytic evolution within species, but little is known about the genetic basis and evolutionary history of CPP. We systematically investigated the genetic architecture of CPP using patterns of transmission ratio distortion (TRD) in F2 and backcros...