The B chromosome polymorphism of the grasshopper Eyprepocnemis plorans in North Africa. IV. Transmission of rare B chromosome variantsBakkali M.a · Camacho J.P.M.b
aInstitute of Genetics, Queen’s Medical Centre, University of Nottingham, Nottingham (England); bDepartamento de Genética, Universidad de Granada, Granada (Spain) Cytogenet Genome Res 106:332–337 (2004) (DOI:10.1159/000079308)
In addition to the principal B chromosome (B1) in Moroccan populations of the grasshopper Eyprepocnemis plorans, nine B chromosome variants appeared at low frequency. The transmission of five of these rare B chromosome variants through females was analysed in three natural populations. Sixteen controlled crosses provided useful information on the transmission of BM2, BM6 and BM7 in Smir, BM3 and BM6 in SO.DE.A. (Société de Développement Agricole lands near Ksar-el-Kebir city), and BM2 and BM10 in Mechra, all located in Morocco. Since six female parents carried two different B variants, a total of 22 progeny analyses could be studied. Intraindividual variation in B transmission rate (kB) was observed among the successive egg pods in 26.7 % of the females, but this variation did not show a consistent temporal pattern. Only the BM2 and BM6 variants in Smir showed net drive, although variation was high among crosses, especially for BM2. These two variants are thus good candidates for future regenerations (the replacement of a neutralized B, B1 in this case, by a new driving variant, BM2 or BM6) in Smir, the northern population where the B polymorphism is presumably older. The analysis of all crosses performed in the three populations, including those reported previously for the analysis of B1 transmission, showed that the largest variance in kB among crosses stands at the individual level, and not at population or type of B levels. The implications of these findings for the occurrence of possible regeneration processes in Moroccan populations are discussed.
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