Cladogenetic correlates of genomic expansions in the recent evolution of actinopterygiian fishes.

Genomic expansions via regional gene duplications and polyploidization events have been implicated as catalysts for rapid cladogenetic speciation in some fish taxa, but any general relationships between genome sizes and patterns of evolutionary radiation remain poorly characterized. Here we examine empirical correlations between genome size and species richness (number of extant species within a given clade) both across Actinopterygii (ray-finned fishes) and within several large actinopterygiian clades. We conducted the analyses both without and with correction (by independent contrasts) for phylogenetic effects. Across the full suite of 461 surveyed genera, relatively small but significant positive correlations were present between species richness and evolutionary increases in C-value. Although many variables (including ecological and behavioural factors) clearly can influence speciation rates, the current results are consistent with the notion that genomic architecture may play a role in species proliferation as well.