Sperm precedence

Definition

The differential fertilization success among sperm from multiple males stored simultaneously within a female's reproductive tract, resulting in non-random paternity of offspring. The two primary patterns are first-male precedence (earlier mates sire more offspring) and last-male precedence (later mates sire more offspring), mediated by mechanisms including sperm stratification, sperm displacement, sperm incapacitation, and female sperm selection.

Etymology

From Latin 'praecedere' (to go before), referring to the priority of one male's sperm over another's in fertilization.

Example

In the yellow dung fly Scathophaga stercoraria, last-male sperm precedence is nearly complete: a female mating twice will produce offspring almost exclusively fathered by the second male, because later ejaculates physically displace earlier-stored sperm from the female's spermatheca.

Synonyms

• sperm priority
• paternity bias

Related Terms

• sperm competition
• cryptic female choice
• sperm displacement
• sperm storage
• multiple mating
• Polyandry
• Bateman gradient

Usage Notes

Sperm precedence patterns are often quantified as P2 (proportion of offspring sired by the second male in a double-mating experiment). The pattern is species-specific and can vary with mating interval, male status, or female age. Last-male precedence is common in many insects and arachnids due to anatomical adaptations for sperm removal or stratification, whereas first-male precedence occurs in some Lepidoptera where sperm is stored in discrete packets with fertilization order matching insemination order. The term is distinguished from 'sperm precedence' in the sense of taxonomic priority (an obsolete usage in nomenclature).