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Male-killing selfish cytoplasmic element causes sex-ratio distortion in Drosophila melanogaster
H Montenegro1, W N Souza, D da Silva Leite
1Departamento de Genética e Evolução, Instituto de Biologia, Universidade Estadual de Campinas, UNICAMP, Campinas, CEP 13083-970, Sao Paulo, Brazil.
Abstract:
Sex ratio distortion induced by a male-killing agent has been found to affect Drosophila melanogaster. The trait was discovered accidentally in a collection of flies from markets in Campinas, São Paulo State, Brazil. Repeated crosses with Canton-S males (for 15 generations to date) and successful transmission using the injection of macerates of sex ratio flies, have shown that the trait is inherited maternally, is cytoplasmic and is infectious. Crosses with strains marked with the visible mutation white and viability experiments at pre-adult stages of development, indicate that the skewed sex ratio results from male mortality before hatching. Males do not transmit the trait to their progeny.
Insights
A male-killing agent causes sex ratio distortion in Drosophila melanogaster by inducing male mortality before hatching. This maternally inherited, infectious, and cytoplasmic trait was discovered in Brazil.
Area of Science:
- * Genetics and evolutionary biology.
- * Microbial-induced speciation and host-pathogen interactions.
Background:
- * Sex ratio distortion, a phenomenon where the expected 1:1 sex ratio is altered, can significantly impact insect populations.
- * Maternally inherited microorganisms are known to cause such distortions in various insect species.
Purpose of the Study:
- * To investigate the cause and inheritance pattern of a newly discovered sex ratio distortion in Drosophila melanogaster.
- * To determine the stage of male mortality and the mode of transmission of the causative agent.
Main Methods:
- * Mating experiments with affected flies and marked strains (e.g., white mutation).
- * Transmission studies via injection of fly macerates.
- * Pre-adult viability experiments.
Main Results:
- * The sex ratio distortion is maternally inherited, cytoplasmic, and infectious.
- * Male mortality occurs before hatching, leading to a skewed sex ratio.
- * Males do not transmit the trait to their offspring.
Conclusions:
- * A maternally inherited, infectious, cytoplasmic agent is responsible for sex ratio distortion in this Drosophila melanogaster population.
- * The agent causes male-specific lethality during embryonic development.
- * This finding has implications for understanding reproductive strategies and population dynamics in insects.