Distribution of chromosome frequencies within a hybrid zone of dichropfus pratensis (Melanoplinae, acrididae)
The widespread South American melanopline grasshopper Dichrophts pratensis is chromosomally polytypic. Seven different Robertsonian translocations between six L-autosomal pairs of the standard all-telocentric karyotype were detected; several races in Argentina are characterized for being polymorphic...
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| Autores principales: | , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_0018067X_v67_n3_p299_Tosto |
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| Sumario: | The widespread South American melanopline grasshopper Dichrophts pratensis is chromosomally polytypic. Seven different Robertsonian translocations between six L-autosomal pairs of the standard all-telocentric karyotype were detected; several races in Argentina are characterized for being polymorphic for one to three of these rearrangements. Within contact zones monobrachial homologies between fusion metacentrics thus occur, and hybrids (complex structural heterozygotes) are formed, in whose meiosis, quadrivalents and quinquivalents prone to non-convergent orientation and unbalanced segregation are produced. We analyse the karyotypic constitution of populations of D. pratensis from a hybrid zone between races that, although sharing the polymorphic 3 /4 fusion, differ for fusions with monobrachial homologies as described above. The Sierra de la Ventana hybrid zone has certain distinctive characteristics: the frequencies and type of the fusions vary abruptly within short distances; these fusions show a mosaic pattern distribution, all the monobrachially homologous fusion metacentrics were found in high frequency. The possible origin of this hybrid zone is discussed. © 1991 The Genetical Society of Great Britain. |
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