Falvey, C.; Geneva, A. J.

Adenoviruses, which infect vertebrates, have a rich history of evolution that includes both host switching and coevolution, particularly within Barthadenovirus, a genus that infects squamate reptiles, birds, and mammals. Potential host-switching events can be identified by comparing the evolutionary histories of viruses and their hosts; however, many Barthadenovirus phylogenies have been inferred from a limited number of easily amplifiable gene segments. Whole-genome sequencing of novel Barthadenovirus strains can provide greater phylogenetic confidence and therefore more accurately identify host-switching events when they occur. Here, we present the whole-genome sequence, annotation, reconciled species tree, and molecular evolution analyses of two isolates of Anolis adenovirus 2, a member of Barthadenovirus. Our two isolates of Anolis adenovirus 2 are sister lineages with very high sequence similarity. Our results support existing hypotheses regarding the ancestral hosts of Barthadenovirus (squamate reptiles) and proposed host-switching events within and between squamate reptiles and other vertebrate classes. We leverage our novel genome annotations to perform comparative synteny analyses, identifying a set of shared genes across Barthadenovirus whose gene order is largely conserved within the genus. Finally, our molecular evolution analyses highlight trends in evolutionary pressures on individual genes: genes associated with viral replication and structure have experienced slower rates of evolution than those encoding proteins involved in host interaction. Our two sequenced isolates of Anolis adenovirus 2 add to an expanding number of Adenovirus genomic resources and facilitate future investigations into the patterns and processes shaping adenovirus diversification.