Mating suppresses sperm-dependent male avoidance in C. elegans hermaphrodites

Area of Science:

• Behavioral Ecology
• Reproductive Biology
• Genetics

Background:

• Female animals often exhibit mate selectivity due to higher reproductive costs.
• In Caenorhabditis elegans, hermaphrodites possess limited self-sperm, and prior research suggests male avoidance.
• The mechanisms and behavioral dynamics of male avoidance in C. elegans remain poorly understood.

Purpose of the Study:

• To quantitatively analyze male-avoidance behavior in C. elegans hermaphrodites.
• To investigate the underlying mechanisms of male avoidance, particularly the role of self-sperm.
• To explore how mating status influences male-avoidance behavior.

Main Methods:

• Locomotor speed measurement of C. elegans hermaphrodites in the presence of males.
• Automated image analysis for precise behavioral tracking.
• Comparison of wildtype, sperm-deficient mutants, aged hermaphrodites, and females of gonochoristic species.

Main Results:

• Wildtype hermaphrodites actively avoided males by increasing locomotor speed upon contact.
• Male avoidance was significantly reduced in sperm-deficient mutants and aged hermaphrodites lacking self-sperm.
• Females of gonochoristic species, without self-sperm, did not exhibit male avoidance.
• Hermaphrodites that had previously mated showed decreased male avoidance.

Conclusions:

• The presence of self-sperm is a key factor promoting male avoidance in C. elegans hermaphrodites, likely to ensure self-fertilization.
• Male avoidance behavior is adaptive and influenced by sperm availability and mating history.
• This study reveals a sperm-dependent mechanism for mate choice in hermaphroditic nematodes.