Molecular evolution of insertions and deletion in the chloroplast genome of Silene

Insertions, deletions, and inversions in the chloroplast genome of higher plants have been shown to be extremely useful for resolving phylogenetic relationships both between closely related taxa and among more basal lineages. Introns and intergenic spacers from the chloroplast genome are now increasingly used for phylogenetic and population genetic studies of populations from a single species, and it is therefore interesting to know whether indels can provide useful data and hence increase the power of intraspecific studies. Here, we show that indels in three cpDNA intergenic spacers and one cpDNA intron for two species of Silene evolve at slightly higher rates than base pair substitutions. Repeat indels appear to have the highest rate of evolution and are thus more prone to homoplasy. We show that coded indel data have high information content for phylogenetic analysis, and indels thus provide useful information to infer phylogenetic relationships at the intraspecific level.