Genotypic variation among different phenotypes within aphid clones

Abstract

SUMMARYMost aphid species (Hemiptera : Aphididae) are parthenogenetic between periods of sexual reproduction. They are also highly polyphenic, with different adult morphs occurring in the life cycle, i . winged, wingless, asexual and sexual. It is assumed that aphids born in a parthenogenetic clonal lineage are genetically identical regardless of the final adult form (with the exception of sexual forms). Using the randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) we have found that different asexual adult phenotypes (winged and wingless) of some clones of two cereal aphid species (the grain aphid, Sitobion a enae (F.) and the bird-cherry aphid, Rhopalosiphum padi (L.)) may be distinguished by the presence or absence of one or more RAPD-PCR bands. In three of nine clones examined, such differences were found, and Southern blotting and hybridization of the discriminating bands confirmed these to be of aphid origin, rather than due to endosymbiotic bacteria or contaminating fungi. The main 248 and 296 bp bands, in the two species, respectively, were sequenced and found to be A\T rich. The smaller band showed 57 % homology with white striated muscle over a stretch of 90 bp. Genomic DNA treated with dimethyl sulphoxide to remove secondary structures still showed differences in RAPD-PCR profiles between winged and wingless morphs within the unusual clones. This discovery may be widespread and therefore it is important to understand the phenomenon in relation to clonal organisms.

Selection in Modular Organisms: Is Intraclonal Variation in Macroalgae Evolutionarily Important?

“…Previous work has documented intraclonal genetic variation in asexually reproducing organisms (e.g., Lynch 1985;Sunnucks et al 1996;Lushai et al 1997), but as these examples and a recent review on intraclonal genetic variation (Lushai and Loxdale 2002) imply, most studies in this field involve clonal unitary organisms, while few address the evolutionary potential of intraclonal variation in modular ones (but see Santelices and Varela 1993;Santelices et al 1995).…”

“…Empirical studies that consider the potential for selection within clonal lineages are rare (Vuorisalo et al 1997) and largely limited to a few taxa, namely higher plants (Acosta et al 1993;Suomela and Ayres 1994) and parthenogenetic arthropods (Lushai et al 1997;). Poore and Fagerström (2000) and Collado-Vides (2002) argue that marine macroalgae offer an excellent opportunity to test the ecological and evolutionary consequences of intraclonal variation.…”

Genetic variability among different Italian populations of the aphidMyzus persicae

“…Reproducible RAPD banding pattern differences were also observed between winged, wingless and sexual (male or female) morphs of the same species (LusHAI et al 1997). The disadvantages of RAPDs as a consequence of dominance and low reproducibility are counterbalanced by the essentially infinite number of genomic markers generated together with the possibility to elute and sequence a peculiar RAPD band to produce a codominant marker (LusHAI et al 1997;BASHASAB et al 2006). In this study, RAPD-PCR was chosen as a convenient molecular method for assessing the genetic variability among 18M.…”

Slaves of the environment: the movement of herbivorous insects in relation to their ecology and genotype

“…The discrimination of the genotypes of the macropterous and brachypterous forms of the brown plant hopper, N. lugens (Kisomoto & Sogawa 1995) may yet be distinguished using molecular markers (cf. Lushai et al (1997b) for intermorph, intraclonal variation in related homopterans).…”