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Assessing Differences in Sperm Competitive Ability in Drosophila
Published on: August 22, 2013
Sperm death and dumping in Drosophila
Rhonda R Snook1, David J Hosken
1Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK. r.snook@sheffield.ac.uk
Nature
|May 1, 2004
Summary
Female fruit flies bias sperm use after mating with multiple males. Contrary to prior beliefs, sperm incapacitation isn't caused by seminal fluids but by sperm aging, and females actively dump stored sperm.
Area of Science:
- Reproductive Biology
- Animal Behavior
- Evolutionary Biology
Background:
- Multiple mating by females is common across species.
- Sperm displacement and incapacitation are proposed mechanisms for sperm use bias.
- Previous research suggested seminal fluids incapacitate rival sperm.
Purpose of the Study:
- To investigate the mechanisms of sperm use bias in Drosophila melanogaster.
- To determine if seminal fluids actively incapacitate rival sperm.
- To elucidate the role of females in regulating stored sperm use.
Main Methods:
- Experimental manipulation of mating and seminal fluid presence.
- Observation of sperm storage and release in female reproductive tracts.
- Analysis of progeny sired by different males.
Main Results:
- Seminal fluids do not kill rival sperm; 'incapacitation' is likely due to sperm aging.
- Females actively release stored sperm (sperm dumping) after mating with a second male.
- Sperm dumping by females occurs independently of incoming sperm or seminal fluids.
Conclusions:
- Sperm aging, not seminal fluid incapacitation, explains reduced fertilization by earlier males.
- Females actively control sperm storage and release, influencing paternity.
- Mechanisms for sperm dumping may involve male cues or female selective ejection.
