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Streptococcal L-forms isolated from Drosophila paulistorum semispecies cause sterility in male progeny
Abstract:
The Drosophila paulistorum complex contains six semispecies that do not normally interbreed. In the laboratory, crosses between semispecies produce fertile daughters and sterile sons. Microbial endosymbionts have been observed in all D. paulistorum flies that display this male sterility. Streptococcal L-forms have been isolated from the Andean-Brazilian (Mesitas) and Transitional (Santa Marta) semispecies and cultured in artificial medium. Transfer of these L-forms from their native hosts into reciprocal semispecies resulted in sterile male progeny. When L-forms were inoculated into the semispecies from which they had been isolated, most of the male progeny were fertile. Control streptococcal L-forms did not show this sterility pattern.
Insights
Microbial endosymbionts, specifically Streptococcal L-forms, cause male sterility in Drosophila paulistorum hybrid crosses. Transferring these L-forms between semispecies confirms their role in reproductive isolation.
Area of Science:
- Evolutionary Biology
- Microbiology
- Genetics
Background:
- The Drosophila paulistorum complex comprises six semispecies with reproductive isolation barriers.
- Male sterility observed in inter-semispecies crosses of Drosophila paulistorum is linked to microbial endosymbionts.
Purpose of the Study:
- To investigate the role of microbial endosymbionts, specifically Streptococcal L-forms, in causing male sterility in Drosophila paulistorum.
- To determine if specific L-forms are responsible for reproductive isolation between Drosophila paulistorum semispecies.
Main Methods:
- Isolation and culturing of Streptococcal L-forms from Andean-Brazilian (Mesitas) and Transitional (Santa Marta) Drosophila paulistorum semispecies.
- Experimental transfer of isolated L-forms into reciprocal semispecies and the original semispecies.
- Observation and analysis of male progeny fertility in experimental crosses.
Main Results:
- Transfer of L-forms from their native hosts into reciprocal semispecies resulted in male progeny sterility.
- Inoculation of L-forms back into their original semispecies led to predominantly fertile male progeny.
- Control streptococcal L-forms did not induce male sterility, indicating specificity.
Conclusions:
- Streptococcal L-forms are identified as causative agents of male sterility in inter-semispecies crosses of Drosophila paulistorum.
- These microbial endosymbionts play a significant role in the reproductive isolation and speciation of the Drosophila paulistorum complex.