Molecular evidence for convergent evolution and allopolyploid speciation within the Physcomitrium-Physcomitrella...

Area of Science:

• Evolutionary biology
• Genomics
• Plant science

Background:

• The moss Physcomitrella patens is a key model for evolutionary-developmental studies.
• The Funariaceae family, including Physcomitrella and Physcomitrium, is of evolutionary interest.
• Natural genetic diversity within the Physcomitrium-Physcomitrella complex was investigated.

Purpose of the Study:

• To elucidate the evolutionary history of Physcomitrella and related species.
• To analyze the genetic diversity within the Physcomitrium-Physcomitrella species complex.
• To revise the taxonomic classification of the species complex.

Main Methods:

• Molecular analysis of the nuclear single-copy gene BRK1.
• Phylogenetic analyses using BRK1 and microsatellite simple sequence repeat (SSR) data.
• Examination of mitochondrial editing site conservation.

Main Results:

• Three Physcomitrium species exhibit larger genomes and two BRK1 homeologs, suggesting allopolyploid hybridization.
• Phylogenetic analyses confirm a polyphyletic origin for three Physcomitrella lineages.
• Differences in mitochondrial editing sites support hybridization and cryptic speciation.

Conclusions:

• A revised classification proposes three distinct species: Physcomitrella patens, P. readeri, and P. magdalenae.
• Secondary reduction in sporophyte complexity is linked to ecological niche adaptation.
• The Funariaceae family offers a valuable system for studying evolutionary and genetic variation.