Molecular phylogenetics and species-level systematics ofBaylisascaris
Lauren E. Camp, Marc R. Radke, Danny M. Shihabi, Christopher Pagan, Guangyou Yang, Steven A. Nadler
Abstract
Nucleotide sequences representing nine genes and five presumptive genetic loci were used to infer phylogenetic relationships among sevenBaylisascarisspecies, including one species with no previously available molecular data. These genes were used to test the species status ofB. procyonis andB. columnarisusing a coalescent approach. Phylogenetic analysis based on combined analysis of sequence data strongly supported monophyly of the genus and separated the species into two main clades. Clade 1 includedB. procyonis,B. columnaris, andB. devosi, species hosted by musteloid carnivores. Clade 2 includedB. transfuga andB. schroederi from ursids,B. ailuri,a species from the red panda (a musteloid), andB. tasmaniensis from a marsupial. Within clade 2, geographic isolates ofB. transfuga,B. schroederi(from giant panda), andB. ailuri formed a strongly supported clade. In certain analyses (e.g., some single genes),B. tasmaniensis was sister to all otherBaylisascaris species rather than sister to the species from ursids and red panda. Using one combination of priors corresponding to moderate population size and shallow genetic divergence, the multispecies coalescent analysis ofB. procyonis andB. columnaris yielded moderate support (posterior probability 0.91) for these taxa as separate species. However, other prior combinations yielded weak or no support for delimiting these taxa as separate species. Similarly, tree topologies constrained to represent reciprocal monophyly of B. columnaris andB. procyonis individuals (topologies consistent with separate species) were significantly worse in some cases, but not others, depending on the dataset analyzed. An expanded analysis of SNPs and other genetic markers that were previously suggested to distinguish between individuals ofB. procyonis andB. columnaris was made by characterization of additional individual nematodes. The results suggest that many of these SNPs do not represent fixed differences between nematodes derived from raccoon and skunk hosts.
copyright:©2018 Published by Elsevier Ltd on behalf of Australian Society for Parasitology.
International Journal for Parasitology: Parasites and Wildlife(2018). DOI: 10.1016/j.ijppaw.2018.09.010
Read Full Text: https://doi.org/10.1016/j.ijppaw.2018.09.010
