The study by Peter Crnokrak and Derek A. Roff reviews the literature to estimate inbreeding depression (δ) in wild species, aiming to understand the biological significance of inbreeding in natural populations. They compiled 169 estimates of δ from various studies, covering 35 species across birds, mammals, poikilotherms (snakes, fish, and snails), and plants. The δ values were corrected for the coefficient of inbreeding (F) to account for its influence on δ. The mean δ values were 0.509 ± 0.081 for homeotherms, 0.201 ± 0.039 for poikilotherms, and 0.331 ± 0.038 for plants. When comparing wild estimates to those from captive zoo populations, the wild estimates showed significantly higher costs of inbreeding at F = 0.25, indicating that natural conditions increase the cost of inbreeding. The study highlights the importance of inbreeding depression in wild populations and suggests that it can have substantial evolutionary consequences, potentially leading to population extinction.The study by Peter Crnokrak and Derek A. Roff reviews the literature to estimate inbreeding depression (δ) in wild species, aiming to understand the biological significance of inbreeding in natural populations. They compiled 169 estimates of δ from various studies, covering 35 species across birds, mammals, poikilotherms (snakes, fish, and snails), and plants. The δ values were corrected for the coefficient of inbreeding (F) to account for its influence on δ. The mean δ values were 0.509 ± 0.081 for homeotherms, 0.201 ± 0.039 for poikilotherms, and 0.331 ± 0.038 for plants. When comparing wild estimates to those from captive zoo populations, the wild estimates showed significantly higher costs of inbreeding at F = 0.25, indicating that natural conditions increase the cost of inbreeding. The study highlights the importance of inbreeding depression in wild populations and suggests that it can have substantial evolutionary consequences, potentially leading to population extinction.