Using Microsatellite Markers To Study The Night Heron Population Genetic Diversity And Reproductive Behavior In The Lower Reaches Of The Yangtze River Region

The Black-crown Night Heron ( Nycticorax nycticorax ) is extremely widespread, occurring in North and South America, Eurasia, and Africa. There are 4 subspecies in the world, and the nominate subspecies, N. n. nycticorax, is found throughout the Old World range. In this thesis eight microsatellites loci were used to investigate genetic diversity, genetic differentiation, population structure, and the genetic relationship of individuals during the breeding season.1. Genetic diversity of three night heron populations in lower reaches of Yangtze River was analyzed by microsatellite markers. Our results show that all loci are highly polymorphism except locus Ah526. Tests of departures from Hardy-Weinberg equilibrium indicated many loci were still significant heterozytosity deficiency after Bonferroni correction. The population was not in Hardy-Weinberg equilibrium. This may correlate with the widely disperse of Black-crowned Night Herons, especially juveniles, after nesting was completed. Also, the migration of the birds could not be negligible in this case. Both in sign test and Wilcoxon sign-rank test, the Black-crowned Night Heron population in lower reaches of Yangtze River was significant deviant from mutation-drift equilibrium with heterozygote excesses. This may show the population had suffered bottleneck effects, and the recent population decline was happened. Fst analysis across all local population and loci indicated that there was low level of divergence between the local populations, and the three local populations may be protected and managed as a management unit (MU).2. Comparisons were taken between the 2003's and 2004's breeding population of Black-crown Night Heron in Siheshan, Wuhu city, using microsatellite markers. The results show that the number of alleles increased with the addition of individual numbers. The ratio of Ne to n did not changed. The expected heterozytosity of the population in 2004 is higher than that of 2003. This indicates that the population in 2004 has lower genetic consistency and more variation. Sign and Wilcoxon sign-rank test indicated there are some loci deviantfrom mutation-drift equilibrium, but the populations in these two years did not significant deviant from mutation-drift equilibrium in TPM model. The results revealed that the population was stable in this area.3. The genetic relationships among the Black-crown Night Herons were investigated using the microsatellite makers, both in Daxiaochang population (Nanjing) and Siheshan population (Wuhu). The results show that some individuals within a nest are not full siblings, and some individuals in different nest have kinships. This may demonstrate that the Black-crown Night Heron have the extra-pair copulation (EPC) during the breeding season.