Understanding the proximate and ultimate causes of genome size variation has been the focus of considerable research. However, the extent and cause of intraspecific variation in genome size are debated and poorly understood. This study aimed to test the role of genome size in adaptation through variations in intraspecific genome size. Genome size was measured in 53 Roscoea tibetica populations from the Hengduan Mountains using flow cytometry. Stomatal size and density data were collected from wild and common garden populations. Associations among genome size, environmental factors, and stomatal traits were explored. We found that high genome size variability was positively correlated with most environmental factors but negatively correlated with solar radiation during the growing season. The environment, rather than geography, significantly influenced variations in genome size. Stomatal traits measured in the wild were significantly correlated with genome size, but no such correlations were detected in the common garden. Populations in the common garden had larger stomatal sizes and lower stomatal densities. Populations with smaller genome size presented a larger degree of stomatal trait variation from the wild to the common garden. Our findings suggest that intraspecific genome size has undergone adaptive evolution driven by environmental stress. A smaller genome size is more advantageous for the alpine ginger to adapt to and thrive in changing alpine habitats.

• Klíčová slova
• Roscoea tibetica, adaptation, common garden, environmental factors, intraspecific genome size, stomatal traits,
• Publikační typ
• časopisecké články MeSH

The nuclear genome is essential for encoding most of the genes required for cellular processes, but its size alone can alter the characteristics of cells and organisms. Yet, genome size variation and its ecological and evolutionary impacts, particularly in microorganisms, are not well understood. We used flow cytometry to estimate genome size and GC content in 53 evolutionary lineages of the microalgal genus Synura (Chrysophyceae, Stramenopiles). Genome size evolution was reconstructed in a phylogenetic framework using molecular markers. A set of genomic, morphological, and ecogeographic variables characterizing Synura lineages was evaluated and tested as predictors of genome size variation in phylogeny-corrected statistical models. Both genome size and GC content varied widely in Synura, ranging from 0.19 to 3.70 pg of DNA and 34.0% to 49.3%, respectively. Genome size variation was mainly associated with cell size, less with silica scale size, and not with scale ultrastructure. Higher soil nitrogen, higher latitudes, and lower temperatures correlated with larger genomes. Genome size evolution in Synura shows potential dynamism, with increases confined to short terminal branches, indicating lower macroevolutionary stability. Lineages with larger genomes exhibited a narrower range of suitable ecological conditions, possibly due to selection acting deleteriously against larger genomes (and cells).

• Klíčová slova
• GC content, PGLS regression, ecological requirements, evolution, flow cytometry, genome size, silica scales,
• MeSH
• délka genomu * MeSH
• dusík * metabolismus   MeSH
• fylogeneze MeSH
• Heterokontophyta * genetika   cytologie   MeSH
• mikrořasy * genetika   cytologie   MeSH
• molekulární evoluce MeSH
• velikost buňky MeSH
• zastoupení bazí MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dusík * MeSH