Shaking the Tree: Multi-locus Sequence Typing Usurps Current Onchocercid (Filarial Nematode) Phylogeny

Area of Science:

• * Molecular Phylogenetics
• * Parasitology
• * Evolutionary Biology

Background:

• * Filarial nematodes (Onchocercidae) include medically and veterinarily significant species.
• * Previous molecular studies lacked broad taxonomic sampling and relied on limited mitochondrial genes (12S rDNA, coxI).
• * These genes are insufficient for resolving higher-level phylogenetic relationships within the family.

Purpose of the Study:

• * To conduct the most extensive molecular phylogenetic analysis of the Onchocercidae family to date.
• * To investigate the evolutionary relationships among its subfamilies using multiple nuclear and mitochondrial gene loci.
• * To re-evaluate existing taxonomic hypotheses based on comprehensive molecular data.

Main Methods:

• * Sequencing of seven gene loci (nuclear and mitochondrial).
• * Phylogenetic analysis of 48 species, representing seven of eight Onchocercidae subfamilies.
• * Utilizing a broad taxonomic sampling strategy for robust evolutionary inference.

Main Results:

• * Confirmed early divergence of Oswaldofilariinae, Waltonellinae, and Icosiellinae subfamilies.
• * Identified Setariinae as a distinct, well-separated clade.
• * Revealed a strongly supported clade comprising Dirofilaria, Loxodontofilaria, and Onchocerca, spanning different subfamilies.
• * Indicated that the current classification of Splendidofilariinae, Dirofilariinae, and Onchocercinae requires reconsideration.

Conclusions:

• * The study provides a more resolved molecular phylogeny for the Onchocercidae family.
• * Findings necessitate a re-evaluation of subfamily boundaries and taxonomic relationships, particularly concerning Dirofilaria, Loxodontofilaria, and Onchocerca.
• * This comprehensive analysis advances our understanding of filarial nematode evolution and classification.