Genome size drives ecological breadth in Pomacentridae reef fishes

Abstract

Genome size (GS) is known to vary widely among fishes. However, evolutionary drivers that shape this variation are largely unknown in Pomacentridae. GS information is available for several Pomacentridae species, which have adapted over evolutionary time mainly in reef environments. In the present study, we used comparative phylogenetic methods to evaluate the role of ecological variables in driving GS variation in 49 species of this family. We also aimed to understand how GS evolved, evaluating five continuous character evolution models. We found that GS varied 1.98-fold, with C-values ranging from 0.68 pg (Pomacentrus auriventris) to 1.35 pg (Chrysiptera hemicyanea). Our phylogenetic analyses, based on mitochondrial and nuclear sequences, revealed that Pomacentridae diversification into two main clades occurred ~58 Mya, with the two clades showing distinct evolutionary trends. Character reconstruction of GS values revealed expansions and retractions in GS with convergences and parallelisms in different lineages. We also found a significant association between GS and body size and proxies of niche breadth (temperature and salinity), suggesting that species with larger genomes tend to occupy a wider niche breadth. Thus, GS variation may influence the life histories of Pomacentridae fishes, independently of their evolutionary relationships.