SAMEA14035948 ERS11639230 uncultured Acetobacteraceae bacterium This sample represents a Third Party Annotation (TPA) Metagenome-Assembled Genome (MAG) assembled from the metagenomic run SRR13685160 of study SRP305791. EBI Generic Generic.1.0 ERC000047 2023-01-03 2023-01-03 SAMEA14035948 EBI European Bioinformatics Institute 2023-01-03T00:32:05Z 2023-01-03T00:32:05Z public SRR13685160_bin.16_CONCOCT_v1.1_MAG Many fragments with little to no review of assembly other than reporting of standard assembly statistics metaspades_v3.13.0 Default CONCOCT v1.1 EMG broker account, EMBL-EBI 2016-01-06 75.32 CheckM 1.0 Algae Green algae Ectosymbionts USA not provided not provided metagenome-assembled genome lichen metagenome lichen metagenome Reductions in genome size and complexity are a hallmark of obligate symbioses. The mitochondrial genome displays clear examples of these reductions, with the ancestral alpha-proteobacterial genome size and gene number having been reduced by orders of magnitude in most descendent modern mitochondrial genomes. Here, we examine patterns of mitochondrial evolution specifically looking at intron size, number, and position across 58 species from 21 genera of lichenized Ascomycete fungi, representing a broad range of fungal diversity and niches. Our results show that the cox1 gene always contained the highest number of introns out of all the mitochondrial protein-coding genes, that high intron sequence similarity can be maintained between different genera, and that lichens have undergone at least two instances of complete, genome-wide intron loss consistent with evidence for genome streamlining via loss of parasitic, noncoding DNA, in Phlyctis boliviensis and Graphis lineola. Notably, however, lichenized fungi have not only undergone intron loss but in some instances have expanded considerably in size due to intron proliferation (e.g., Alectoria fallacina and Parmotrema neotropicum), even between closely related sister species (e.g., Cladonia). These results shed light on the highly dynamic mitochondrial evolution that is occurring in lichens and suggest that these obligate symbiotic organisms are in some cases undergoing recent, broad-scale genome streamlining via loss of protein-coding genes as well as noncoding, parasitic DNA elements. SAMN17834480 SRR13685160_bin.16_CONCOCT_v1.1_MAG uncultured Acetobacteraceae bacterium NextSeq 550 multi-marker approach