Global phylogeography and evolution of chelonid fibropapilloma-associated herpesvirus.

A global phylogeny for chelonid fibropapilloma-associated herpesvirus (CFPHV), the most likely aetiological agent of fibropapillomatosis (FP) in sea turtles, was inferred, using dated sequences, through Bayesian Markov chain Monte Carlo analysis and used to estimate the virus evolutionary rate independent of the evolution of the host, and to resolve the phylogenetic positions of new haplotypes from Puerto Rico and the Gulf of Guinea. Four phylogeographical groups were identified: eastern Pacific, western Atlantic/eastern Caribbean, mid-west Pacific and Atlantic. The latter comprises the Gulf of Guinea and Puerto Rico, suggesting recent virus gene flow between these two regions. One virus haplotype from Florida remained elusive, representing either an independent lineage sharing a common ancestor with all other identified virus variants or an Atlantic representative of the lineage giving rise to the eastern Pacific group. The virus evolutionary rate ranged from 1.62×10(-4) to 2.22×10(-4) substitutions per site per year, which is much faster than what is expected for a herpesvirus. The mean time for the most recent common ancestor of the modern virus variants was estimated at 192.90-429.71 years ago, which, although more recent than previous estimates, still supports an interpretation that the global FP pandemic is not the result of a recent acquisition of a virulence mutation(s). The phylogeographical pattern obtained seems partially to reflect sea turtle movements, whereas altered environments appear to be implicated in current FP outbreaks and in the modern evolutionary history of CFPHV.

Evidence for transoceanic migrations by loggerhead sea turtles in the southern Pacific Ocean.

Post-hatchling loggerhead turtles (Caretta caretta) in the northern Pacific and northern Atlantic Oceans undertake transoceanic developmental migrations. Similar migratory behaviour is hypothesized in the South Pacific Ocean as post-hatchling loggerhead turtles are observed in Peruvian fisheries, yet no loggerhead rookeries occur along the coast of South America. This hypothesis was supported by analyses of the size-class distribution of 123 post-hatchling turtles in the South Pacific and genetic analysis of mtDNA haplotypes of 103 nesting females in the southwest Pacific, 19 post-hatchlings stranded on the southeastern Australian beaches and 22 post-hatchlings caught by Peruvian longline fisheries. Only two haplotypes (CCP1 93% and CCP5 7%) were observed across all samples, and there were no significant differences in haplotype frequencies between the southwest Pacific rookeries and the post-hatchlings. By contrast, the predominant CCP1 haplotype is rarely observed in North Pacific rookeries and haplotype frequencies were strongly differentiated between the two regions (F(st)=0.82; p=<0.00001). These results suggest that post-hatchling loggerhead turtles emerging from the southwest Pacific rookeries are undertaking transoceanic migrations to the southeastern Pacific Ocean, thus emphasizing the need for a broader focus on juvenile mortality throughout the South Pacific to develop effective conservation strategies.