Helitrons are enriched in lichenized fungi with long generation length and small distribution sizes

<p>Mobile genetic elements (MGEs) have the potential to drive genome evolution by introducing mutations and causing structural instability and chromosomal rearrangements, particularly under conditions like environmental or genetic stress. In this study, we generated 18 new long-read reference genomes for lichenized fungi, which form obligate mutualistic symbioses with algae or a cyanobacteria. We used these genomes to investigate the connections between dominant reproductive mode, distribution size, and generation length with the abundance and spatial distribution of MGEs for 28 lichenized fungal reference genomes using a phylogenetic comparative framework. We found that species with smaller distribution sizes and those with longer generation lengths had a higher genomic DNA transposon load, and that their genomes were enriched with Rolling Circle transposons, specifically, which contradicts broad patterns identified in previous studies of MGEs in rare species. Disproportionate distributions of MGEs in rare and range-restricted species may disrupt genomic stability, decrease fitness, and be reflective of species experiencing a greater degree of stress. Also, greater MGE activity may be an important source of novel genetic diversity in isolated populations with limited gene flow. Further research is needed to understand the potential mechanisms driving MGE proliferation in these genomes, and if MGE content is predictive of increased extinction risk in rare species.</p>

Name thesis:degree_name

Master of Science (MS) in Biology

Level thesis:degree_level

Thesis: EWU Only

Discipline thesis:degree_discipline

Biology

Year dc:date.available

2025

Author dc:creator

• Paulsen, Julianna

• Biodiversity
• Other Ecology and Evolutionary Biology
• Other Genetics and Genomics

Statement dc:rights

• Access restricted for 2 years to EWU users with an active EWU NetID

Repository record dc:identifier

https://dc.ewu.edu/theses/973

OAI identifier oai:identifier

oai:dc.ewu.edu:theses-1975