Mitochondrial Phylogeography And Population History Of Finless Porpoises In Sino-Japanese Waters And Temporal Change In Genetic Diversity Of Finless Porpoises In Chinese Waters

This thesis includes three chapters:1. Some advances in the studies of cetaceans in Chinese waters were reviewed.2. Three hundred and forty-five base pairs (bp) of the mitochondrial DNA (mtDNA) control region were sequenced to analyze the genetic diversity, population structure and history, and phylogeography of finless porpoises (Neophocaena phocaenoides) in Chinese and Japanese waters of the North Pacific. Nucleotide and haplotype diversities were 0.44% and 0.79±0.01 for Chinese and Japanese waters, respectively, but varied significantly among populations. Analysis of molecular variance (AMOVA) showed a high level of genetic structure between populations (Φ_ST=0.61, p<0.001; F_ST=0.52, p<0.001). Eleven of 18 haplotypes were restricted to a single population, common haplotypes were found in two to four populations but no haplotype was found throughout Sino-Japanese waters, suggesting multiple colonization events followed by limited gene flow. The inferred age of demographic expansion was from the end stage of the last ice age to the Holocene. No obvious phylogeographic pattern was revealed, including between saline and fresh water populations. A low level of genetic diversity for each population and high among-population differentiation in haplotype frequency were revealed, which suggest a role for random genetic drift, recent demographic bottlenecks and reduced or limited gene flow in these populations. Some conservation considerations, with special reference to the unique Yangtze...