[Appropriate sample size and molecular marker loci in the study of genetic diversity of Ocomelania hupensis].
OBJECTIVE
To explore the reasonable sample size and the number of molecular marker loci in the study of amplified fragment length polymorphism (AFLP) being used to analyze the genetic diversity of Ocomelania hupensis.


METHODS
The ribbed-shelled snails coming from Yueyang, Hunan province, were selected to analyze the relationship of the number of AFLP molecular marker loci and sample size with the reliability of information on genetic variation for Ocomelania hupensis by AFLP method.


RESULTS
Correlations found among the numbers of AFLP molecular marker loci and the sample size with reliable information on genetic variation for Ocomelania hupensis. When sample size was less than 7 individuals, the total number of AFLP loci, the number of polymorphic loci, Nei's gene diversity and Shannon's information index appeared great changes. However, when sample size was bigger than 30 individuals, the values of these indices tended to be stabilized. When the number of AFLP loci was less than 128, the frequency of polymorphic loci, Nei's gene diversity, Shannon's information index and the standard deviation of these two indices changed greatly. Again, when the number of loci was bigger than 338, the values of these indices tended to be stabilized.


CONCLUSIONS
When the genetic diversity of Ocomelania hupensis were analyzed by AFLP method, the sample size coming from each snail population should not be less than 30 individuals and the number of molecular loci analyzed not less than 338.
Zhou
Yi-Biao
YB
Department of Epidemiology, Public Health School of Fudan University, Shanghai 200032, China.
Jiang
Qing-Wu
QW
Zhao
Gen-Ming
GM
Wei
Jian-Guo
JG