Ejaculates are not used as nuptial gifts in simultaneously hermaphroditic snails

Area of Science:

• * Evolutionary Biology
• * Reproductive Biology
• * Animal Behavior

Background:

• * Sexual selection drives diverse male reproductive strategies to enhance fertilization success.
• * Nuptial gifts, including sperm and nutrients, are common in many species, aiding female egg provisioning.
• * Simultaneous hermaphrodites possess both male and female reproductive organs, complicating the study of reproductive strategies.

Purpose of the Study:

• * To investigate the nutritional and material investment in ejaculates and spermatophores in simultaneous hermaphrodites with different mating systems.
• * To test the hypothesis that nutrient donation is ineffective in reciprocal mating due to zero net gain.
• * To explore the broader functions of ejaculate transfer beyond nutrient provision in hermaphroditic reproduction.

Main Methods:

• * Measurement of material investment (dry weight) and resource content (carbon and nitrogen) in ejaculates and spermatophores.
• * Comparison of investment in ejaculates/spermatophores versus eggs.
• * Analysis of material and resource exchange during reciprocal matings in snails.

Main Results:

• * Ejaculates and spermatophores represent a low investment compared to eggs, not significantly contributing to egg production.
• * In reciprocal matings, snails exchanged similar amounts of material and resources, indicating no net gain.
• * The energy balance of nutrient exchange in reciprocal mating is likely negative due to metabolic costs.

Conclusions:

• * Generalizing male reproductive strategies across different mating systems requires caution.
• * Nuptial gift donation in simultaneous hermaphrodites may not serve as a primary nutrient source during reciprocal mating.
• * Ejaculate absorption in hermaphrodites could be crucial for sperm competition and cryptic female choice, rather than nutrient acquisition.