Diversity of chromosomal segregational mechanisms in Mantispids (Neuroptera: Mantispidae) |
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Authors: | Sally Hughes-Schrader |
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Affiliation: | (1) Department of Zoology, Duke University, 27706 Durham, N. C., USA |
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Abstract: | The asymmetry of karyotype previously regarded as a Family character of the Mantispidae is absent in 4 species representative of one of the species-groups tyxonomically distinguishable in the Mantispas of the Western Hemisphere. Further diversity is evident in the evolutionary loss of the Y chromosome in Plega dactylota Rehn and the substitution of a Neo-XY system for distance segregation in P. signata (Hagen). In the Mantispas pseudo- or sticky sex-bivalents are present at diakinesis with a maximum frequency of 50% in M. fuscicornis Banks. By final metaphase this is reduced to 2% or less except in M. uhleri Banks in which 6% of the spermatocytes retain sex-bivalents. Univalent autosomes, observed in all but one of the species studied, occur in less than 1% of the cells at first metaphase except in M. interrupta Say and Plega dactylota in which their frequency approaches 8%. The precocious segregation of these unconjoined autosomes shows that univalency, rather than any sex-related attribute, underlies distance segregation.Dedicated with affection and admiration to Professor Hans Bauer on the occasion of his 75th birthday |
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