Phylogenomics and population genomics of seal lice

M.S. LEONARDI; J. NEGRETE; S. VIRRUETA HERRERA; K. JOHNSON; A. SWEET

Brno

Congreso; VII International Conference on Phthiraptera; 2018

Sucking lice belonging to the family Echinophthiriidae are peculiar in the sense that they infest amphibious hosts, as walruses, seals, and sea lions. Along the evolutionary time, echinophthiriids have developed unique morphological, physiological, behavioral, and ecological adaptations to cope with the amphibious lifestyle of their hosts. Host specificity of echinophthiriids ranges from 100%, involving 1 or 2 host genera (Lepidophthirus, Proechinophthirus, and Latagophthirus), to genera as Echinophthirius and Antarctophthirus, which infest species in 5 and 10 host genera, respectively. However, conclusive evidence regarding the evolutionary patterns of echinophthiriids is not available. This study investigates the relation among sucking lice parasitizing seals and sea lions. We obtained total genomic DNA from specimens of A. microchir from Australia (AmAus) and Patagonia (AmPat), A. carlinii (Ac), A. lobodontis (Al), A. ogmorhini (Ao), Lepidophthirus macrorhini (Lm), and P. fluctus (Pf). Using this data, we inferred a phylogenetic tree for echinophthiriids. We also used the genomic data to estimate theta, i.e. effective population size. Our analysis showed that the divergence between AmAus and AmPat is enough to consider them different species. On the other hand, the genetic distances between Ac, Al, and Ao are very small compared to divergences between the other species. Lastly, we found that Lm possesses the highest effective population size following by Al, while AmAus, Ao, and Ac present similar theta. We would have expected a higher effective population size for Al, because population size of crabeater seals is at least one order of magnitude higher than the other seals species.