title: Physiological approach to explain the ecological success of 'superclones' in aphids: interplay between detoxification enzymes, metabolism and fitness.
abstract: 'Superclones' are predominant and time-persistent genotypes, exhibiting constant fitness across different environments. However, causes of this ecological success are still unknown. Therefore, we studied the physiological mechanisms that could explain this success, evaluating the effects of wheat chemical defences on detoxification enzymes [cytochrome P450 monooxygenases (P450), glutathione S-transferases (GST), esterases (EST)], standard metabolic rate (SMR), and fitness-related traits [adult body mass and intrinsic rate of increase (r(m))] of two 'superclones' (Sa1 and Sa2) of the grain aphid, Sitobion avenae. Additionally, we compared 'superclones' with a less-frequent genotype (Sa46). Genotypes were reared on three wheat cultivars with different levels of hydroxamic acids (Hx; wheat chemical defences). Detoxification enzymes and SMR did not differ between wheat hosts. However, GST and EST were different between 'superclones' and Sa46, while Sa1 showed a higher SMR than Sa2 or Sa46 (p=0.03). Differences between genotypes were found for r(m), which was higher for Sa1 than for Sa2 or Sa46. For all cases, genotype-host interactions were non-significant, except for aphid body mass. In conclusion, 'superclones' exhibit a broad host range, flat energetic costs for non-induced detoxification enzymes, and low variation in their reproductive performance on different defended hosts. However, physiological specialization of 'superclones' that could explain their ecological success was not evident in this study.
authors.affiliation: Instituto de Ecología y Evolución, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile. lecastane@gmail.com
authors.forename: Luis E
authors.initials: LE
authors.lastname: Castañeda
authors.forename: Christian C
authors.initials: CC
authors.lastname: Figueroa
authors.forename: Eduardo
authors.initials: E
authors.lastname: Fuentes-Contreras
authors.forename: Hermann M
authors.initials: HM
authors.lastname: Niemeyer
authors.forename: Roberto F
authors.initials: RF
authors.lastname: Nespolo
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001042:Aphids / Q000201:enzymology / Q000235:genetics* / Q000502:physiology*; D001481:Basal Metabolism; D049628:Body Size; D002677:Chile; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D005787:Gene Frequency; D056084:Genetic Fitness / Q000502:physiology*; D005838:Genotype; D005982:Glutathione Transferase / Q000378:metabolism*; D006790:Host-Parasite Interactions; D018895:Microsatellite Repeats / Q000235:genetics; D014908:Triticum / Q000737:chemistry / Q000469:parasitology*
chemical_list: D003577:Cytochrome P-450 Enzyme System; D005982:Glutathione Transferase