Heatmap of milk protein gene copy numbers across mammals. Milk protein genes were clustered by copy number using the K-means algorithm followed by seriation within each cluster. Major trends, which convey the consensus profile of the cluster, are delineated by brackets. Most milk protein genes are either present as a single copy in each mammalian genome or as a single copy in all therian genomes. Duplicated genes are expanded after platypus in either a general or a species- or clade-specific manner. Black squares indicate that the gene was not found in a particular species, yellow-green squares indicate a single copy of the gene, and red squares indicate two or more copies of the gene. Brighter red squares indicate higher copy numbers.
Lemay et al. Genome Biology 2009 10:R43 doi:10.1186/gb-2009-10-4-r43