The relationship between genetic diversity and environmental factors of 15 Patelloida pygmaea populations in the Bohai Sea was studied by PCR and DNA sequencing. A total of 264 polymorphic loci were found in the 16 S rRNA partial sequence of the 180 individuals,and 153 transitions as well as 114 transversions were defined by 32 haplotypes. The base contents of C,T,A and G were 18. 12%,27. 74%,33. 07%,and 21. 07%,respectively. The haplotype diversity was0. 835 1 ± 0. 019 1,and the nucleotide diversity was 0....