Phylogenomic analyses reveal introgression and cryptic speciation in the globally distributed, vector-transmitted pathogen Plasmodium relictum

Esther Weyer; Angela N. Theodosopoulos; Vaidas Palinauskas; Staffan Bensch; Helena Westerdahl; Melanie Duc; Arif Ciloglu; Xi Huang; Kyeong Soon Kim; Yoshio Tsuda; Carter T. Atkinson; Pavel Zehtindjiev; Robert C. Fleischer; Nichelle M. VanTassel; Scott A. Taylor; Olof Hellgren; Vincenzo A. Ellis

doi:10.1016/j.ympev.2026.108642

Phylogenomic analyses reveal introgression and cryptic speciation in the globally distributed, vector-transmitted pathogen Plasmodium relictum

Molecular Phylogenetics and Evolution

By: Esther Weyer, Angela N. Theodosopoulos, Vaidas Palinauskas, Staffan Bensch, Helena Westerdahl, Melanie Duc, Arif Ciloglu, Xi Huang, Kyeong Soon Kim, Yoshio Tsuda, Carter T. Atkinson, Pavel Zehtindjiev, Robert C. Fleischer, Nichelle M. VanTassel, Scott A. Taylor, Olof Hellgren, and Vincenzo A. Ellis

https://doi.org/10.1016/j.ympev.2026.108642

Metrics

Web analytics dashboard Metrics definitions

Links

More information: Publisher Index Page (via DOI)
Download citation as: RIS | Dublin Core

Abstract

Establishing species limits is challenging, particularly for pathogens of wildlife. These pathogens can be difficult to sample and culture, and their genome sequencing must often be conducted in the presence of high levels of host DNA. Plasmodium relictum is a mosquito-vectored avian malaria pathogen that is a globally distributed host generalist, comprised of several genetic lineages. We used sequence capture data from 52 P. relictum infections originating from multiple continents to generate a genomic dataset of the pathogen. With this data, we established a robust phylogeny and determined species limits among P. relictum lineages. We generated phylogenomic trees by maximum likelihood and Bayesian methods with multi-species coalescent models and confirmed robustness of the topology by varying the amount of missing data in the analyses. Our results suggest the existence of two cryptic species among the infections we analyzed and provide evidence of genetic introgression between these species. One of the cryptic species, GRW4, devastated the endemic and immunologically naïve avifauna of Hawaii after its introduction to the islands ca. 100 years ago, and so was tested for positive selection in the GRW4 Hawaiian clade. Although we hypothesized it would be released from host selective pressures, we did not find evidence of positive selection in the Hawaiian GRW4 clade, and we discuss possible explanations. Overall, our results underscore the importance of genomic analyses for resolving pathogen species limits and understanding pathogen evolution.

Suggested Citation

Weyer, E., Theodosopoulos, A.N., Palinauskas, V., Bensch, S., Westerdahl, H., Duc, M., Ciloglu, A., Huang, X., Kim, K.S., Tsuda, Y., Atkinson, C., Zehtindjiev, P., Fleischer, R.C., VanTassel, N.M., Taylor, S.A., Hellgren, O., and Ellis, V.A., 2026, Phylogenomic analyses reveal introgression and cryptic speciation in the globally distributed, vector-transmitted pathogen Plasmodium relictum: Molecular Phylogenetics and Evolution, v. 222, 108642, 10 p., https://doi.org/10.1016/j.ympev.2026.108642.

Additional publication details
Publication type	Article
Publication Subtype	Journal Article
Title	Phylogenomic analyses reveal introgression and cryptic speciation in the globally distributed, vector-transmitted pathogen Plasmodium relictum
Series title	Molecular Phylogenetics and Evolution
DOI	10.1016/j.ympev.2026.108642
Volume	222
Year Published	2026
Language	English
Publisher	Elsevier
Contributing office(s)	Pacific Island Ecosystems Research Center
Description	108642, 10 p.