Gametic interactions promote inbreeding avoidance in house mice

Area of Science:

• Reproductive biology
• Evolutionary genetics
• Animal behavior

Background:

• Inbreeding typically reduces reproductive success and population fitness.
• Polyandrous females may avoid inbreeding via paternity-biasing mechanisms, including differential sperm use.
• Demonstrating sperm selection is challenging due to confounding paternity-biasing factors.

Discussion:

• This study provides in vitro evidence of gametic-level sperm selection in mice.
• Fertilization bias favored non-sibling sperm over sibling sperm.
• No differences in sperm motility or swimming performance were observed, indicating egg-driven selection.

Key Insights:

• Females exhibit cryptic female choice by selecting against related sperm at the gametic level.
• This selection mechanism operates independently of sperm motility or swimming ability.
• Gametic proteins likely mediate this form of inbreeding avoidance.

Outlook:

• Investigating the specific gametic proteins involved in sperm selection.
• Exploring the prevalence of this mechanism in other species.
• Understanding the evolutionary implications of cryptic female choice for reproductive isolation.