Inbreeding Depression
The reduced fitness and health of offspring resulting from mating between close relatives. Occurs because harmful recessive alleles are more likely to be expressed when both parents carry them.
Used in the Books
This term appears in 3 chapters:
"It breaks down genetic isolation, introduces variation that drift or selection has removed, rescues small populations from inbreeding depression (reduced fitness from mating between relatives), and can either facilitate or prevent local adaptation."
"... (vulnerabilities within populations): Small population size: Populations below ~500-1,000 individuals face elevated extinction risk from: - Inbreeding depression** (Chapter 2): Mating between relatives exposes deleterious recessive alleles, reducing fitness. Inbred populations have lower survival, reproduction..."
"Disease outbreaks impact both populations (parvo virus decimated wolves in 1981; chronic wasting disease threatens moose). Inbreeding depression in the small wolf population reduced fitness. Climate change reduced ice bridge formation, preventing wolf immigration. Third, predators regulate bu..."
Biological Context
Small, isolated populations suffer inbreeding depression because relatives are the only available mates. Effects include reduced fertility, weaker immune systems, and developmental abnormalities. Genetic rescue through introducing individuals from other populations can reverse inbreeding depression.
Business Application
Organizational inbreeding: when companies only hire from within or from the same sources, they accumulate harmful 'recessive traits'—blind spots, outdated practices, and groupthink.