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.
","abstract_html":"<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>","abstract_has_math":false,"creators":["Paulsen, Julianna"],"institution":null,"degree_name":"Master of Science (MS) in Biology","degree_level":"Thesis: EWU Only","degree_discipline":"Biology","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-01-01T08:00:00Z","date_published":"2025-01-01T08:00:00Z","updated_at":"2026-07-24T02:13:07Z","subjects":["Biodiversity","Other Ecology and Evolutionary Biology","Other Genetics and Genomics"],"languages":[],"rights":["Access restricted for 2 years to EWU users with an active EWU NetID"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://dc.ewu.edu/theses/973","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Paulsen, Julianna"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2027-06-12T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis: EWU Only"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS) in Biology"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Biodiversity","Other Ecology and Evolutionary Biology","Other Genetics and Genomics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["Access restricted for 2 years to EWU users with an active EWU NetID"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://dc.ewu.edu/theses/973"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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.
"]},{"key":"dc:title","label":"Title","values":["Helitrons are enriched in lichenized fungi with long generation length and small distribution sizes"]}]}],"canonical_facts":{"dc:creator":["Paulsen, Julianna"],"dc:date.available":["2027-06-12T07:00:00Z"],"dc:description.abstract":["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.
"],"dc:identifier":["https://dc.ewu.edu/theses/973"],"dc:rights":["Access restricted for 2 years to EWU users with an active EWU NetID"],"dc:subject":["Biodiversity","Other Ecology and Evolutionary Biology","Other Genetics and Genomics"],"dc:title":["Helitrons are enriched in lichenized fungi with long generation length and small distribution sizes"],"thesis:degree_discipline":["Biology"],"thesis:degree_level":["Thesis: EWU Only"],"thesis:degree_name":["Master of Science (MS) in Biology"]},"updated_at":"2026-07-24T02:13:07Z"}