Crested Ibis Population Pedigree Construction And Genetic Diversity

Crested ibis(Nipponia Nippori),a kind of peculiar wading bird in east Asians facing its extinction because of humanbeings' economic activities.Seven crested ibises found at Yong county Shaanxi Province in 1981 were the all wild individuals left in the world then.To protect this rare bird,scholars have carried out a great deal of researches on it in many areas.However,till now, studies is mainly confined to some areas such as ecology and morphology, little was done in the area of molecular biology.Phenomina such as disable individuals increasing and adults' producing ability decreasing occurred more frequent in recent years.These badly affected the existence and development of this species.So,getting the information about crested ibis' gene and genetic diversity through studies at molecular level and setting up scientific producing and protecting projections are becoming urgent tasks.Randomly amplified polymorphic DNA(RAPD) is a common method to analyze DNA,and is based on PCR using a series of primers made up of randomly arranged basesAlthough the sites detected by a single primer are limited,the entire genome can be inspected when many primers were used. Because of the method is convenient and fast, and no molecular information about the species to be studied is needed, RAPD is widely used in many areas such as study of phylogenetic tree and genetic diversity.We studied 32 crested ibises from Yong county and 5 crested ibises from Beijing Zoo by RAPD. Similarity coefficient and genetic distances between two arbitrary individuals were caculated according to the data of experiments,the pedigree was constructed by two means(They were UPGMA and parsimony),and genetic diversity was discussedBased on selecting the best conditions of PCR with OPG and OPA primers from Operon company,we obtained 163 bands using 24 random primers.In other words,163 sites in crested ibis' genome were detected.The bands from 23 primers showed polymorphism.Minimurn of polymorphic ratio was 0,maximum was 85.71%,and average was 48.99%.In the population which was composed by 37 individuals, most of genetic distances between two arbitrary individuals were less than 0.1.The results showed that the degree of similarity among crested ibises was high while genetic diversity in thepopulation was low accordingly. We think this situation should be owed to bottleneck effect and a rather frequency of inbreeding. It is necessary for a species' adaptation and evolutionary potential to keep genetic variety at a relative level. Genetic diversity in the population must not be lost furthermore and gene exchange among individuals should be enhanced as much as possible to avoid extinction of crested ibis. At the same time,close breeding should be strictly avoided,too. Because callow birds had not be marked with rings in the early period of protection, the pedigree was confused. So,it is very difficult to carry out artificial pairing. For its reference value to set reasonable breeding plan, the pedigree chart constructed by us can be applied in the protection to crested ibis.According to a good breeding project, inbreeding can be avoided and gene exchange can be increased. That means genetic diversity in crested ibises can be sustained, and on the base the populations' adaptive capacity and evolutionary potential should be promoted. In this way,the rare bird will be protected more successfully.