Abstract
We determined female genome sizes using flow cytometry for 211 Drosophila melanogaster sequenced inbred strains from the Drosophila Genetic Reference Panel, and found significant conspecific and intrapopulation variation in genome size. We also compared several life history traits for 25 lines with large and 25 lines with small genomes in three thermal environments, and found that genome size as well as genome size by temperature interactions significantly correlated with survival to pupation and adulthood, time to pupation, female pupal mass, and female eclosion rates. Genome size accounted for up to 23% of the variation in developmental phenotypes, but the contribution of genome size to variation in life history traits was plastic and varied according to the thermal environment. Expression data implicate differences in metabolism that correspond to genome size variation. These results indicate that significant genome size variation exists within D. melanogaster and this variation may impact the evolutionary ecology of the species. Genome size variation accounts for a significant portion of life history variation in an environmentally dependent manner, suggesting that potential fitness effects associated with genome size variation also depend on environmental conditions.
Highlights
Genome size evolution is extensive and ubiquitous
There are two major classes of hypotheses regarding genome size evolution, those that attribute its causes to evolutionarily neutral processes and those that suggest a role for selection
Numerous correlations between genome size and fitnessrelated phenotypes have been documented, suggesting selection could play a role in genome size evolution
Summary
Genome size evolution is extensive and ubiquitous. the mechanisms by which this occurs are poorly understood and hotly debated, despite a wealth of information connecting genome size shifts to numerous phenotypes, lineages, and abiotic environments [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]. While the connection between genome size variation and phenotype is generally recognized for order of magnitude changes in genome size and for interspecific phenotype comparisons, there is little evidence that these effects act on the relatively small magnitude of variation in genome size expected within a species – especially in non-plants. Neutral factors such as founder effects and random drift [15,19] and changes in insertion/deletion balance [13] have been proposed as mechanisms for intraspecific changes in genome size. Conflicting theories of genome size evolution exist and neither camp has definitively documented the potential for selection rather than chance as a driving force
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