Two related Data Desk graphs used to display and compare the genetic structure of part of a single chromosome between two strains of mice. Five strains of mice were fully sequenced by Celera Genomics. Any pair of strains of mice have slightly different gene sequences that are highlight in these graphs. Each point represents a single nucleotide polymorphism (SNP); when the SNP differs between a pair of strains it is labeled in red whereas if the SNP does not differ it is labeled in blue. The file includes just over 200,000 rows of data (1 SNP per row). The X-axis records the position along a chromosome measured in millions of base pairs (a typical chromosome is about 150 million base pairs (Mb) long). The Y axis of the top graph is the distance between adjacent SNPs in base pairs on a log scale.

The lower graph is a different rendition that illustrates the use of Data Desk smoothers. The SNPs have been recoded using a dummy variable as either 1 (different) or 0 (same) and then the median smooth was computed along 2 Mb of the chromosome.