D3154: Do environmental factors impact drosophilid genome size evolution?

The amount of nuclear DNA, or genome size, varies widely across the insect tree of life with no clear relationship with organismal complexity. Some insects have only 100 million base pairs, while others reach nearly 18 billion base pairs. Many hypotheses have been proposed to explain this genomic variation. Some suggest relationships to environmental adaptations, while others suggest size is driven by effective population size. To date, no single hypothesis clearly explains the genome size variation observed. In order to investigate these hypotheses, we utilize data from nearly 150 drosophilid species. With over a century's worth of research on their genomes, life history characteristics, and behaviors, there is no shortage of available data for these organisms. We mined data from peer-reviewed papers and publicly available datasets pertaining to genome size, thermal limits, climatic variables, geographic location, haploid chromosome number, and a variety of other life-history characteristics. We then investigated the relationship of genome size to these variables using linear regression models and comparative phylogenetic analyses in R. Early work has found that while there is some relationship between genome size and climatic variables, much of these relationships are nullified when accounting for evolutionary relatedness. Since this early work, we have greatly expanded our dataset and explanatory variables. We present here the more complete and informative models of these relationships using this newly obtained data.