Integrating morphology and genetics to estimate species diversity, host specificity and life cycles of echinostome trematodes

Abstract

Estimates of trematode parasite diversity may be inaccurate due to cryptic species and phenotypic plasticity. If misidentifications occur, inferences about life cycles and host specificity will also be erroneous, which limits our understanding of the role of trematode species in wildlife disease. Echinostome trematodes are a group in which cryptic species and phenotypic plasticity has been documented. These parasites infect different wildlife species including some of conservation concern. I performed phylogenetic analysis using DNA sequences from larvae and adults and confirmed 11 lineages/species of echinostomes in Manitoba wetlands. First and final hosts were genetically confirmed for five lineages/species. I tested the hypothesis of crypsis in two nominal species (Echinostoma trivolvis and Echinostoma revolutum sensu lato) using genetically-identified specimens and museum specimens. These species were morphologically indistinguishable indicating that misidentifications may have occurred in past studies. My thesis revealed more species diversity, elucidated life cycles, and confirmed crypsis in echinostome parasites.