A sex-specific linkage map of the white shrimp Penaeus (Litopenaeus) vannamei based on AFLP markers

We report the construction of sex-specific linkage maps for the white shrimp Penaeus (Litopenaeus) vannamei (Penaeidae; Crustacea). Linkage information was generated using amplified fragment length polymorphism (AFLP) markers in a mapping panel consisting of 42 individuals derived from a commercial cross. We used 103 primer combinations that produced 741 segregating bands. From them, 477 segregated in a 1:1 model, 181 in a 3:1 model, 62 fitted both models and 21 fitted neither model. A total of 394 loci with a 1:1 segregation ratio were mapped to unique positions in the male and female maps using a pseudotestcross strategy. A total of 51 and 47 linkage groups were detected for the male and female maps respectively, in comparison to 44 haploid groups expected from the karyotype. The female map covered 2771 Kosambi units (cM) and was 24% longer than the male map (2116 cM long). The distribution of the markers showed that both maps had low saturation and clustering at short linkage distances. Markers with a distorted segregation were observed as previously reported in other shrimp species. The estimated genomic length indicates that the P. vannamei genome has higher recombination rates than closely related species. We demonstrate the feasibility of implementing molecular techniques