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Evidence for predominant clones in a cyclically parthenogenetic organism provided by combined demographic and genetic analyses
Author(s) -
Haack L.,
Simon J.C.,
Gauthier J.P.,
Plantegenest M.,
Dedryver C.A.
Publication year - 2000
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1046/j.1365-294x.2000.01108.x
Subject(s) - biology , parthenogenesis , aphid , sitobion avenae , host (biology) , generalist and specialist species , population , host adaptation , adaptation (eye) , asexual reproduction , sexual reproduction , ecology , zoology , genetics , aphididae , botany , homoptera , pest analysis , habitat , gene , demography , embryo , genome , sociology , neuroscience
Aphids are particularly interesting models in the study of genetic and demographic components of plant adaptation because of their breeding system which combines parthenogenesis and sexual reproduction (i.e. cyclical parthenogenesis), and the frequent emergence of host‐adapted races reported in this group. In this paper, patterns of host adaptation were assessed on local populations of the aphid Sitobion avenae by following their demographic and genetic structure in a maize field for two consecutive years. The existence of putative generalist (polyphagous) or specialized (host‐adapted) genotypes was also investigated by comparing the genotypic distribution of this aphid on maize and other cultivated host plants, using five microsatellite loci. Although population dynamics revealed strong variation in aphid abundance during the colonization period on maize, two genotypes identified at seven additional microsatellite loci were predominant and exhibited stable frequencies over cropping season and between years. Based on present and earlier studies, these two prevalent genotypes were shown to survive on different host plants other than maize, to colonize large geographical zones and to persist parthenogenetically for several years. All these data strongly suggest that these two genotypes are asexual generalist clones that could have been favoured by agricultural practices encountered in western Europe. Besides these two clones, a continual replacement of rare genotypes was observed on maize in both years. Hypotheses involving selection via aphid–plant interactions and natural enemies were proposed for explaining the disappearance of these genotypes on maize.