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Title: Widespread convergence in toxin resistance by predictable molecular evolution
Contributor(s): Ujvari, Beata (author); Casewell, Nicholas R (author); Madsen, Thomas (author); Hillis, David M (editor); Sunagar, Kartik (author); Arbuckle, Kevin (author); Wuster, Wolfgang (author); Lo, Nathan (author); O'Meally, Denis (author); Beckmann, Christa  (author)orcid ; King, Glenn F (author); Deplazes, Evelyne (author)
Publication Date: 2015
Open Access: Yes
DOI: 10.1073/pnas.1511706112Open Access Link
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Abstract: The question about whether evolution is unpredictable and stochastic or intermittently constrained along predictable pathways is the subject of a fundamental debate in biology, in which understanding convergent evolution plays a central role. At the molecular level, documented examples of convergence are rare and limited to occurring within specific taxonomic groups. Here we provide evidence of constrained convergent molecular evolution across the metazoan tree of life. We show that resistance to toxic cardiac glycosides produced by plants and bufonid toads is mediated by similar molecular changes to the sodium-potassium-pump (Na+/K+-ATPase) in insects, amphibians, reptiles, and mammals. In toad-feeding reptiles, resistance is conferred by two point mutations that have evolved convergently on four occasions, whereas evidence of a molecular reversal back to the susceptible state in varanid lizards migrating to toad-free areas suggests that toxin resistance is maladaptive in the absence of selection. Importantly, resistance in all taxa is mediated by replacements of 2 of the 12 amino acids comprising the Na+/K+-ATPase H1–H2 extracellular domain that constitutes a core part of the cardiac glycoside binding site. We provide mechanistic insight into the basis of resistance by showing that these alterations perturb the interaction between the cardiac glycoside bufalin and the Na+/K+-ATPase. Thus, similar selection pressures have resulted in convergent evolution of the same molecular solution across the breadth of the animal kingdom, demonstrating how a scarcity of possible solutions to a selective challenge can lead to highly predictable evolutionary responses.
Publication Type: Journal Article
Source of Publication: Proceedings of the National Academy of Sciences, 112(38), p. 11911-11916
Publisher: National Academy of Sciences
Place of Publication: United States of America
ISSN: 0027-8424
Field of Research (FOR): 060809 Vertebrate Biology
060802 Animal Cell and Molecular Biology
060806 Animal Physiological Ecology
Socio-Economic Outcome Codes: 970106 Expanding Knowledge in the Biological Sciences
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
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