Genetic Linkage Maps of the Guppy ( Poecilia reticulata ): Assignment of RAPD Markers to Multipoint Linkage Groups

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Abstract
Genetic linkage maps of the guppy (Poecilia reticulata) were constructed from independent crosses between the Tuxedo strain and a feral line (Wildtype). Segregation patterns of random amplified polymorphic DNA (RAPD) markers and phenotypic markers were investigated in F2 offspring of Tuxedo ♂♂ × Wildtype ♀♀ and Wildtype ♂♂ × Tuxedo ♀♀ crosses. Among the 300 and 276 RAPD markers scored for the respective crosses, linkages were identified for 230 and 212, respectively. The Tuxedo ♂♂ × Wildtype ♀♀ and Wildtype ♂♂ × Tuxedo ♀♀ maps spanned 2100 Kosambi centiMorgans (cMK) and 1900 cMK, respectively, in 28 linkage groups. Average marker resolution was 10 cMK. Genome length was estimated at 4410 cMK and 4060 cMK for the respective crosses, with an average physical distance of 166 kbp/cMK. Several RAPD markers were closely linked to or mapped onto the loci for the sex-determining region (SdR), and the sex-linked black caudal-peduncle (Bcp) and red tail (Rdt) genes. These primary linkage maps are the initial step toward the construction of a composite high-density map to facilitate map-based cloning and marker-assisted selection of quantitative trait loci that are essential for the development of comprehensive breeding programs for the guppy.