Detecting adaptive trait introgression between Iris fulva and I. brevicaulis in highly selective field conditions

The idea that: natural hybridization has served as an important force in evolutionary and adaptive diversification has gained considerable momentum in recent. years. By combining genome analyses with a highly selective field experiment, we provide evidence for adaptive trait introgression between two naturally hybridizing Louisiana Iris species, flood-tolerant hi, fulva and dry-adapted L brevicaulis We planted reciprocal backcross (BC1) hybrids along With pure-species plants into natural settings that, due to a flooding event, favored I. fulva. As expected, L fulva plant, survived at much higher rates than I. brevicaulis plants. Backcross hybrids toward I. fulva (BCIF) also survived at significantly higher rates than the reciprocal backcross toward L brevicaulis (BCIB). Survivorship of BCIB hybrids was strongly influenced by the presence of a number of introgressed L fulva, alleles located throughout the genome, while survivorship in the reciprocal BCIF hybrids was heavily influenced by two epistatically acting QTL of opposite effects. These results demonstrate the potential for adaptive trait introgression between these two species and may help to explain patterns of genetic variation observed in naturally occurring hybrid zones.