The genomic architecture of introgression during Rhododendron speciation.

Area of Science:

• Genomics
• Plant speciation
• Population genetics

Background:

• Understanding genomic architecture's role in gene flow is crucial for plant speciation.
• Rhododendron subsect. Scabrifolia provides a model system to study speciation mechanisms.

Purpose of the Study:

• To investigate if differential gene flow between genomic compartments (A and B) drives speciation in Rhododendron subsect. Scabrifolia.
• To characterize chromatin organization and analyze gene flow patterns across species.

Main Methods:

• Chromosome-level genome assembly of Rhododendron spinuliferum.
• Genome resequencing of 139 individuals across 15 populations of 8 Rhododendron species.
• Analysis of genomic differentiation and introgression across A and B compartments.

Main Results:

• Significant disparities in genomic differentiation between A and B compartments observed.
• B compartment (centromere-associated) shows higher genetic differentiation.
• A compartment (gene-rich) shows lower differentiation and higher localized introgression (f_dm values).

Conclusions:

• Heterogeneous gene flow across genomic compartments contributes to Rhododendron speciation.
• Differential gene flow dynamics may play a critical, underappreciated role in plant speciation.