Inbreeding depression in an outbred stickleback population

Area of Science:

• Evolutionary Biology
• Population Genetics
• Conservation Genetics

Background:

• Inbreeding depression, the reduced fitness of offspring from related parents, is typically rare in large, outbred populations.
• Large populations can harbor recessive deleterious mutations, normally masked in heterozygotes, leading to significant fitness loss when inbreeding occurs.

Purpose of the Study:

• To investigate the occurrence and impact of inbreeding depression in a large, outbred marine nine-spined stickleback (Pungitius pungitius) population.
• To quantify the inbreeding load and explore the relationship between parental genetic relatedness and offspring survival.

Main Methods:

• Utilized experimental cross data to assess offspring survival.
• Employed genome-wide identity-by-descent (IBD) analysis to measure parental genetic relatedness.
• Calculated the inbreeding load (B) based on IBD sharing and survival data.

Main Results:

• A significant decrease in offspring survival probability was observed with increasing parental IBD sharing.
• The average inbreeding load (B) was estimated at 10.5.
• Paternal inbreeding coefficient positively influenced offspring survival, suggesting complex interactions between inbreeding and relatedness.

Conclusions:

• Substantial inbreeding depression and a significant inbreeding load can exist even in large, outbred wild populations.
• Fine-scale genetic relatedness among mates is a critical factor influencing offspring survival and should be considered in future studies.
• The findings highlight the importance of understanding genetic structure for effective conservation strategies.