Baylisascaris laevis, Leidy, 1856

Barrera, McIntyre A., Janes, Jasmine K. & Gorrell, Jamieson C., 2022, Molecular phylogenetics and systematics of two enteric helminth parasites (Baylisascaris laevis and Diandrya vancouverensis) in the Vancouver Island marmot (Marmota vancouverensis), International Journal for Parasitology: Parasites and Wildlife 19, pp. 301-310 : 305

3.2. Molecular phylogenetics of Baylisascaris laevis

All BI and MP reconstructions across mt-trees, nr-trees, and combined trees consistently resolved B. laevis as a monophyletic group with high support ( Figs. 2–4 , Supplementary Figs. S1–S 3 ). BI and MP single gene trees ( Figs. S4–S 15) reflected this relationship. All mt-trees, nr-trees, and combined trees supported the two clades resolved by Camp et al. (2018), splitting B. columnaris , B. procyonis , and B. devosi from B. schroederi , B. transfuga , and B. ailuri ( Figs. 2–4 , S 1–S 3 ), although most trees placed B. tasmaniensis as sister to all other Baylisascaris species, apart from the BI mt-tree ( Fig. 2 ). The mt-trees, nr-trees, and combined trees showed strong support for B. laevis as sister to the clade containing B. columnaris , B. procyonis , and B. devosi ( Figs. 2–4 , S 1–S 3 ). Most single gene trees supported this relationship, with the following exceptions: 1) the 12S MP and BI trees had an alternate branching pattern between B. laevis and B. devosi ; 2) the cox 1 MP tree placed B. laevis as sister to all Baylisascaris ; and 3) the cox 2 BI tree, and 28S trees from MP and BI, presented unresolved polytomies between B. laevis and the other species in this clade (Supplementary Figs. S3 and S 4 , S6, and S9–S11 respectively).

The mean pairwise sequence divergence (Mean ± SD) for B. laevis was 0.96 ± 0.70% between VI and Alaska; 1.12 ± 1.01% between VI and Idaho; and 1.12 ± 0.78% between VI and all mainland sequences ( Table 4). The low divergence between VI and Alaska was consistent with topologies reconstructed in the BI and MP trees for individual nuclear genes, which showed VI and Alaska samples as sister taxa (Supplementary Figs. S10–S15). The trees for individual mitochondrial genes, and the concatenated mt-trees, were unable to resolve the relationships among B. laevis samples or placed the VI sample as sister to all other B. laevis samples ( Fig. 2 , S 1 , and S4–S9).

Figures

Fig. 2. Bayesian consensus phylogram based on Baylisascaris and outgroup alignments of concatenated mitochondrial sequences (12S, cox1, and cox2) from GenBank and this study (B. laevis). Branch labels represent Bayesian posterior probabilities. Branch lengths are scaled to expected number of substitutions per site. Abbreviations refer to sampling sites (AK = Alaska, ID = Idaho, CT = Connecticut; IL = Illinois; CA = California; WV = West Virginia; ALB = Alberta). See also Table 1.

Fig. 3. Bayesian consensus phylogram based on Baylisascaris and outgroup alignments of concatenated nuclear sequences (28S, ITS, and ard1) from GenBank and this study (B. laevis). Branch labels represent Bayesian posterior probabilities. Branch lengths are scaled to expected number of substitutions per site. Abbreviations refer to sampling sites (AK = Alaska, ID = Idaho, CT = Connecticut; IL = Illinois; CA = California; WV = West Virginia; ALB = Alberta). See also Table 1.

Fig. 4. Bayesian consensus phylogram based on Baylisascaris and outgroup alignments of concatenated mitochondrial (12S, cox1, and cox2) and nuclear sequences (28S, ITS, and ard1) from GenBank and this study (B. laevis). Branch labels represent Bayesian posterior probabilities. Branch lengths are scaled to expected number of substitutions per site. Abbreviations refer to sampling sites (AK = Alaska, ID = Idaho, CT = Connecticut; IL = Illinois; CA = California; WV = West Virginia; ALB = Alberta). See also Table 1.

Fig. 1. Known geographic distributions of Baylisascaris laevis and Diandrya composita in North America.