The article discusses the use of 'animal models' in estimating genetic parameters in natural populations. These models, based on mixed models, allow for the estimation of variance components and prediction of breeding values, helping to account for environmental variation and provide insights into evolutionary processes. The animal model incorporates multigenerational data and complex pedigrees, enabling the estimation of additive genetic variance and other causal components of phenotypic variance. It is particularly useful in natural populations where environmental heterogeneity is common, as it can account for shared environmental effects, maternal effects, and permanent environmental effects. The animal model is a form of mixed model that includes both fixed and random effects. It is used to estimate variance components and predict breeding values, which are essential for understanding the genetic basis of quantitative traits. The model allows for the inclusion of various random effects, such as common environment, maternal effects, and permanent environment, which can contribute to phenotypic variance. The model is particularly effective in natural populations where environmental variation is significant, as it can account for these effects and provide more accurate estimates of heritability and other genetic parameters. Studies using the animal model have been conducted on various wild populations, including ungulates and birds. These studies have shown that the model can effectively estimate genetic parameters and account for environmental and maternal effects. The model has been applied to data from populations such as red deer, collared flycatchers, and Soay sheep, providing insights into the genetic basis of traits and the impact of environmental and maternal factors on phenotypic variation. The model's ability to handle complex data and account for multiple sources of variation makes it a powerful tool for studying evolutionary processes in natural populations.The article discusses the use of 'animal models' in estimating genetic parameters in natural populations. These models, based on mixed models, allow for the estimation of variance components and prediction of breeding values, helping to account for environmental variation and provide insights into evolutionary processes. The animal model incorporates multigenerational data and complex pedigrees, enabling the estimation of additive genetic variance and other causal components of phenotypic variance. It is particularly useful in natural populations where environmental heterogeneity is common, as it can account for shared environmental effects, maternal effects, and permanent environmental effects. The animal model is a form of mixed model that includes both fixed and random effects. It is used to estimate variance components and predict breeding values, which are essential for understanding the genetic basis of quantitative traits. The model allows for the inclusion of various random effects, such as common environment, maternal effects, and permanent environment, which can contribute to phenotypic variance. The model is particularly effective in natural populations where environmental variation is significant, as it can account for these effects and provide more accurate estimates of heritability and other genetic parameters. Studies using the animal model have been conducted on various wild populations, including ungulates and birds. These studies have shown that the model can effectively estimate genetic parameters and account for environmental and maternal effects. The model has been applied to data from populations such as red deer, collared flycatchers, and Soay sheep, providing insights into the genetic basis of traits and the impact of environmental and maternal factors on phenotypic variation. The model's ability to handle complex data and account for multiple sources of variation makes it a powerful tool for studying evolutionary processes in natural populations.