ASSORTATIVE MATING AND NATURAL SELECTION IN AN IRIS HYBRID ZONE

Area of Science:

• Plant genetics
• Evolutionary biology
• Ecology

Background:

• Hybridization in plant populations can lead to novel genotypes and complex mating dynamics.
• Understanding mating systems is crucial for predicting evolutionary trajectories and genetic diversity.

Purpose of the Study:

• To investigate assortative mating and selection in a hybrid Iris population.
• To determine the genetic structure and mating patterns of I. fulva and I. brevicaulis hybrids.
• To assess the viability and genotypic distribution of progeny.

Main Methods:

• Analysis of flowering phenology across different genotypes.
• Application of a mixed-mating model to assess assortative mating.
• Comparison of observed and expected progeny genotypic distributions.
• Examination of genetic markers (RAPD, chloroplast DNA).

Main Results:

• Flowering periods of I. fulva, I. brevicaulis, and hybrid genotypes overlapped, creating opportunities for inter-genotype mating.
• Progeny exhibited a higher frequency of intermediate genotypes than the adult generation, with some intermediate genotypes being aborted.
• I. fulva genotypes showed preferential mating with similar genotypes, while I. brevicaulis genotypes did not exhibit discrimination.
• Asymmetrical mating was observed, likely due to pollen-style interactions or zygote abortion.

Conclusions:

• The hybrid Iris population exhibits effective asymmetrical mating, driven by genotype-specific fertilization or viability.
• Directional gene flow occurs from I. fulva to I. brevicaulis via nuclear genetic elements.
• These mating patterns influence introgression and the evolution of hybrid genotypes.