Investigating the role of life-history traits in mammalian genomes

Genome size evolution has intrigued many evolutionary biologists. Ultimately, the reasons that genomes have become large are proliferation of non-coding elements and/or duplication events. The proximate causes are related to phylogeny, life-history traits and environmental factors. Genome size in mammals exhibits little interspecific variation compared with other taxa. The proximate causes and the evolutionary patterns shaped by phylogeny or life-history traits are largely unknown for mammals. Here, with a dataset of 121 species of mammals. we studied the variations of genome size associated with life history using a comparative quantitative analysis. The results showed that the genome size was positively associated with body size, but not with four other life-history traits (i.e.. gestation period, weaning age, litter size, and longevity) in these species. For Primates, Rodentia and Chiroptera, the genome size was not correlated with life-history traits. Our results suggest that evolution of a large genome may result from increased cell size and thus facilitate the evolution of large bodies.