AFLP-BASED LINKAGE MAPS FOR THE EASTERN AND PACIFIC OYSTERS

¹ Haskin Shellfish Research Laboratory, Rutgers University, 6959 Miller Avenue, Port Norris, NJ 08349, USA.

² Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao, Shandong 266071, PRC

Amplified fragment length polymorphisms (AFLPs) are efficient and reliable markers that are widely used for linkage mapping in agricultural species. We tested AFLP markers for linkage mapping in the eastern (Crassostrea virginica) and Pacific (C. gigas) oysters. The number of segregating (in female or male parent) AFLP markers used was 298 for C. virginica and 295 for C. gigas. Female and male framework maps were constructed at a LOD score of 3.0 or a maximum interval of 30 cM. In C. virginica, the female map consisted of 99 markers in 15 linkage groups covering 1064 cM at an average interval of 13 cM. The male map consisted of 127 markers in 13 groups covering 789 cM at an average interval of 7 cM. In C. gigas, the female map consisted of 108 markers in 13 linkage groups spanning 1051 cM at an average interval of 11 cM. The male map had 87 markers in 11 groups, a length of 760 cM and an average interval of 10 cM. The estimated genome length was almost the same in the two species: 1540 vs. 1697 cM for females, and 1005 vs. 1000 cM for males (C. virginica vs. C. gigas). The female map was significantly longer than the male map in both species. The estimated genome coverage was 78-90% for C. virginica and 72-82% C. gigas. Additional markers including microsatellites are being added to increase genome coverage and consolidate linkage groups.