Population genetic structure and dispersal model of an invasive rodent (Rattus exulans) in Taiwan: a microsatellite analysis.

• Main Authors: Huang-Chi Chen, 陳皇奇
• Other Authors: Hai-Yin Wu
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/00322175075081632846

碩士 === 國立東華大學 === 自然資源管理研究所 === 94 === Rattus exulans had invaded Taiwan for years. The existing surveys reveal that the range of R. exulans is expanding. The information relevant to the control of the species is scanty, which can be supplemented by recent advance in population molecular genetics. In this study, such approach was employed to examine the population genetic structure of R. exulans in order to investigate its dispersal potential and to detect genetic differentiation and bottleneck within population. The effect of the intensive eradication program held in 2002 over the study area was also evaluated. Seven polymorphic microsatellite makers were identified from 19 primers of R. norvegicus. Genotype data were established for samples captured in 2001 and 2003 within the study site of 24km2 in Ji-An township of Hualien county. Individuals captured in 2001 were assigned into 2 subgroups with distinct distribution pattern. A similar pattern was found when all the individuals captured in both years were combined for assignment analysis. However, the subgrouping pattern was not observed in 2003. It suggests that invasion by R exulans might occurred at least twice and the eradication program in 2002 might enhance exchange or interbreeding of the 2 subgroups. The mode-shift indicator and the He-Heq analysis reveal that R. exulans have been in the study area for a long period. The M ratio analysis of samples in 2001 and 2003 also indicate the population should have experienced serious bottleneck effect probably during invasion spatial genetic autocorrelation and relatedness analyses show that the extent of home range was smaller than 200m and most dispersal occurred within the range of 600~2400m in 2001 and 1800~2400m in 2003. The ranging patterns of the two years and the lack of population bottleneck in 2003 imply that the genetic composition of R. exulans was not affected by the eradication program. The spatial distribution patterns of highly related pairs among 2003 samples indicated that R. exulans would disperse from un-controlled sites to controlled sites. The management implication of this study is that, if the objective of the eradication program is to removal the entire population of R. exulans, it needs to be intensive and thorough. In addition, the removal and monitoring measures must be applied to a broader area than the distribution range of the species.