TABLE 1.

Relationships between genome size and map size in vertebrates

Organism	Genome size (Gbp)a	Nb	Chromosomal armsb	Map size (cM)c	Obligatory map (N × 50 cM)	Proportion obligatoryd	cM/arm
Mouse	2.7	20	20	1361	1000	0.73 (0.73)	68.1
Rat	2.6	21	33	1749	1050	0.60 (0.94)	53.0
Human	3.0	23	46	3615	1150	0.32 (0.64)	78.6
Chicken	1.2	38	44	3800	1900	0.50 (0.58)	86.4
Zebrafish	1.8	25	50	3011	1250	0.42 (0.83)	60.2
Ambystoma (map)e	30.0	14	28	5152	700	0.14 (0.27)	184.0
Ambystoma (χ)f	30.0	14	28	5650	700	0.12 (0.25)	201.8

^aReferences: mouse, Mouse Genome Sequencing Consortium (2002); rat, Rat Genome Sequencing Project Consortium (2004); human, International Human Genome Sequencing Consortium (2000); chicken, International Chicken Genome Sequencing Consortium (2005); zebrafish, Kelly et al. (2000); Ambystoma, Licht and Lowcock (1991).

^bThe haploid number of chromosomes. Smaller chicken microchromosomes (10–38; Masabanda et al. 2004) are tabulated as one-armed chromosomes. References: mouse, Mouse Genome Sequencing Consortium (2002); rat, Rat Genome Sequencing Project Consortium (2004); human, International Human Genome Sequencing Consortium (2000); chicken, International Chicken Genome Sequencing Consortium (2005); zebrafish, Gornung et al. (2000); Ambystoma, Callan (1966).

^cReferences: mouse, Steen et al. (1999); rat, Brown et al. (1998); human, Kong et al. (2002); chicken, Groenen et al. (2000); zebrafish, Kelly et al. (2000).

^dNumbers in parentheses represent the obligatory proportion of the map assuming one obligate chiasma per arm.

^eMap size is estimated as the sum of LG1–14.

^fMap size is estimated as 50 cM × the average number of chiasmata (Callan 1966).