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Influence of chromosome two arrangements on viability and developmental time of Drosophila buzzatti

Juan Jose Fanara; Esteban Hasson; Constantina Rodriguez; Juan Cesar Vilardi

GIBE, Departamento Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pab II, 1428 . Buenos Aires, Argentina. Send correspondence to J.J.F.

ABSTRACT

The influence of an inversion polymorphism of the cactophilic Drosophila buzzatii on life history traits was studied in experimental populations derived from the natural population of Arroyo Escobar, Argentina.
The experiments designed to determine the best breeding conditions showed that 40 first instar larvae per 5 cc. of culture medium minimized the effects of crowding. Significant differences for first instar larva to adult viability, developmental time and thorax length were detected among karyotypes. However, none of the karyotypes exhibited the best performance for all traits studied. In addition, significant differences were observed between homo and heterokaryotypes. The latter had, in general, better performances than homokaryotypes. However, the advantage of heterokaryotypes cannot be invoked to explain the maintenance of the inversion polymorphism.
When the fitness values estimated under laboratory conditions were compared to the results of our previous selection components analysis performed on the same natural population, some discrepancies, attributable to the differences in breeding conditions were detected.

Keywords: chromosome; developmental time; Drosophila buzzatti.

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