PHYLOGEOGRAPHY OF BAYLISASCARIS PROCYONIS (RACCOON ROUNDWORM) IN NORTH AMERICA.

Area of Science:

• Parasitology
• Molecular Ecology
• Evolutionary Biology

Background:

• Baylisascaris procyonis is a nematode parasite found in raccoons.
• Understanding its genetic diversity and population structure is crucial for ecological and epidemiological studies.

Purpose of the Study:

• To investigate the genetic variation and geographic structure of Baylisascaris procyonis populations.
• To assess the influence of host (raccoon) distribution and historical environmental factors on parasite genetics.

Main Methods:

• Mitochondrial cytochrome c oxidase 1 (COI) gene sequencing was performed on 115 Baylisascaris procyonis individuals.
• Samples were collected from 44 raccoon hosts across 13 U.S. states and 1 Canadian province.
• Genetic variation, haplotype diversity, nucleotide diversity, and population structure (Φst) were analyzed.

Main Results:

• Low overall genetic distance (1.6%) supports Baylisascaris procyonis as a single species.
• Moderate overall haplotype (h=0.60) and nucleotide (π=0.0053) diversity were observed.
• Low haplotype diversity east of the Mississippi River suggests high gene flow or a selective sweep.
• Significant genetic structure was found between populations east and west of the continental divide, with no shared haplotypes.
• Samples from Colorado exhibited higher diversity and differentiation compared to midwestern and eastern samples.

Conclusions:

• Baylisascaris procyonis populations exhibit phylogeographic patterns mirroring those of their raccoon hosts.
• The divergence between eastern and western populations may be linked to vicariance events, such as Pleistocene glaciation and climate fluctuations.
• Further research into the impact of host-parasite co-evolution and paleoclimatic events is warranted.