Field and greenhouse studies to address this question are ongoing. Some models of hybrid zone evolution predict that hybrid genotypes are universally unfit relative to parental genotypes due to inherent genetic incompatibility. If this is the case, hybrid genotypes should have lower fitness, regardless of environmental conditions. To isolate individual environmental variables that are expected to have a potential effect on Iris performance greenhouse experiments have been designed to address flooding, drought, and shade, and competition is being investigated in the field. Preliminary results indicate that there is an effect of environment on hybrid versus parental fitness.
Some hybrid genotypes seem to be capable of outperforming parental genotypes in some conditions.
Field site near St. Martinville, Louisiana in early spring 1999. Plants pictured here are a mix of I.fulva, I. brevicaulis and their hybrids, but are virtually indistinguishable before flowers appear. Crosses are being made this growing season to generate seed for this experiment. Hybrids are often visibly distinct from their parents. In addition to the more obvious differences in floral color and flower stalk stature, I am measuring ecophysiological characters of I. fulva, I. brevicaulis and their hybrids to compare hybrid and parental phenotypes.