Genetic variation within a parthenogenetic lineage

A clone of the grain aphid Sitobion avenae F. was maintained parthenogenetically over thirty‐two generations (n= 344) in a constant environment: a new generation being set up by a female selected at random from the preceding generation. Genomic DNA from individual aphids was screened for genetic stability using RAPD‐PCR with a previously tested ten‐mer primer. A putative germ‐line mutation was noted in generation 14 and somatic mutations were noted in generations 12, 25, 27 and 29. There were no differences in the RAPD‐PCR profiles of winged and wingless morphs and samples tested for symbiotic DNA. No endobiotic fungal organism was associated with the clone. Southern blotting and hybridization studies indicated that band additions were of aphid origin. However, the RAPD‐PCR profiles of the germ‐line and somatic mutation samples were unique from other aphid clones cultured during the experimental period. This paper documents discernible genetic changes occurring within an animal clonal lineage over time and impacts on the consequences this may have for clonal systems.