title: Parallel molecular evolution in an herbivore community.
abstract: Numerous insects have independently evolved the ability to feed on plants that produce toxic secondary compounds called cardenolides and can sequester these compounds for use in their defense. We surveyed the protein target for cardenolides, the alpha subunit of the sodium pump, Na(+),K(+)-ATPase (ATPα), in 14 species that feed on cardenolide-producing plants and 15 outgroups spanning three insect orders. Despite the large number of potential targets for modulating cardenolide sensitivity, amino acid substitutions associated with host-plant specialization are highly clustered, with many parallel substitutions. Additionally, we document four independent duplications of ATPα with convergent tissue-specific expression patterns. We find that unique substitutions are disproportionately associated with recent duplications relative to parallel substitutions. Together, these findings support the hypothesis that adaptation tends to take evolutionary paths that minimize negative pleiotropy.
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhen
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Aardema
authors.forename: Edgar M
authors.initials: EM
authors.lastname: Medina
authors.forename: Molly
authors.initials: M
authors.lastname: Schumer
authors.forename: Peter
authors.initials: P
authors.lastname: Andolfatto
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D029062:Apocynaceae / Q000378:metabolism* / Q000469:parasitology; D002298:Cardenolides / Q000378:metabolism*; D019143:Evolution, Molecular; D058685:Genetic Pleiotropy; D060434:Herbivory / Q000235:genetics*; D006790:Host-Parasite Interactions / Q000235:genetics*; D007313:Insecta / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009928:Organ Specificity; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D002298:Cardenolides; D000254:Sodium-Potassium-Exchanging ATPase