Latitudinal variation in genome size in crustaceans

In animals, genome size is correlated with many traits that also vary with latitude, such as body size and developmental rate. Crustaceans have highly variable genome sizes (ranging nearly 650-fold), and some polar crustaceans have exceptionally large genomes. Here, we investigate whether genome size is positively correlated with latitude across 275 species of decapods, amphipods and copepods. We also test whether this relationship is independent of other factors that co-vary with genome size and latitude (body size, habitat and larval development) using phylogenetic generalized least-squares methods and model selection using Akaike's information criterion. In amphipods, all well-supported models explaining genome size included latitude, whereas in copepods the supported models included body size, but not latitude. In decapods, there was a significant correlation between genome size and number of larval stages; however, model testing indicated that no single factor was most well supported in explaining genome size correlations. Although genome size generally increases with latitude across crustaceans, it is clearly a complex trait that differs among taxonomic groups.