Nucleotide Diversity of the Colorless Green Alga Polytomella parva (Chlorophyceae, Chlorophyta): High for the Mitochondrial Telomeres, Surprisingly Low Everywhere Else

Silent-site nucleotide diversity data (pi(silent)) can provide insights into the forces driving genome evolution. Here we present psilent statistics for the mitochondrial and nuclear DNAs of Polytomella parva, a nonphotosynthetic green alga with a highly reduced, linear fragmented mitochondrial genome. We show that this species harbors very little genetic diversity, with the exception of the mitochondrial telomeres, which have an excess of polymorphic sites. These data are compared with previously published pi(silent) values from the mitochondrial and nuclear genomes of the model species Chlamydomonas reinhardtii and Volvox carteri, which are close relatives of P. parva, and are used to understand the modes and tempos of genome evolution within green algae.