Supernumerary segments in five species of grasshoppers (Orthoptera: Acridoidea) |
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Authors: | J. P. M. Camacho J. Cabrero |
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Affiliation: | (1) Departamento de Genética, Facultad de Ciencias, Universidad de Granada, Granada, Spain |
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Abstract: | Supernumerary segments have been observed in five species of grasshoppers: Calliptamus barbarus, Oedipoda fuscocincta, Acrotylus insubricus, Omocestus raymondi and Chorthippus ariasi. In four cases they are located in the S-chromosomes, but in A. insubricus they are carried by the megameric pair (M9). In C. barbarus and O. fuscocincta we have observed non-homologous association during diplotene between the extra segments and the X-chromosome. The supernumerary segments of these two species are distally located. However, in anaphase-I the unequal bivalents divide reductionally in 30% and 20% of the cells, respectively. Finally, the supernumerary segments of C. barbarus do not produce any effect on mean chiasma frequency, but they decrease significantly the between-cell variance of chiasmata in males carrying them. |
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