Organism	Characteristics	Genetic Correlation
Cattle	Milk yield and percentage of butterfat	−0.38
Pig	Weight gain and back-fat thickness	0.13
	Weight gain and efficiency	0.69
Chicken	Body weight and egg weight	0.42
	Body weight and egg production	−0.17
	Egg weight and egg production	−0.31
Mouse	Body weight and tail length	0.29
Fruit fly	Abdominal bristle number and sternopleural bristle number	0.41
Source: After D. S. Falconer and t. F. C. Mackay. Introduction to Quantitative Genetics (Pearson, New York, 1996), p. 314.