Temporal genetic variation in populations of the limpet Cellana grata from Hong Kong shores |
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Authors: | Wai-Chuen Ng F C C Leung Solomon T C Chak G Slingsby Gray A Williams |
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Institution: | (1) The Swire Institute of Marine Science and Division of Ecology & Biodiversity, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong;(2) School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong |
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Abstract: | Variations in the relative contributions of gene flow and spatial and temporal variation in recruitment are considered the
major determinants of population genetic structure in marine organisms. Such variation can be assessed through repeated measures
of the genetic structure of a species over time. To test the relative importance of these two phenomena, temporal variation
in genetic composition was measured in the limpet Cellana grata, among four annual cohorts over 10 years at four rocky shores in Hong Kong. A total of 408 limpets, comprising individuals
from 1998, 1999, 2006 and 2007 cohorts were screened for genetic variation using five microsatellite loci. Minor but significant
genetic differentiation was detected among samples from the 1998/1999 collection (F
ST = 0.0023), but there was no significant differentiation among the 2006/2007 collection (F
ST = 0.0008). Partitioning of genetic variation among shores was also significant in 1998/1999 but not in the 2006/2007 collection,
although there was no correlation between genetic and geographic distances. There was no significant difference between collections
made in 1998/1999 and 2006/2007. This lack of clear structure implies a high level of gene flow, but differentiation with
time may be the result of stochastic recruitment variation among shores. Estimates of effective population size were not high
(599, 95% C.L. 352–11397), suggesting the potential susceptibility of the populations to genetic drift, although a significant
bottleneck effect was not detected. These findings indicate that genetic structuring between populations of C. grata in space and time may result from spatio-temporal variation in recruitment, but the potential development of biologically
significant differentiation is suppressed by a lack of consistency in recruitment variability and high connectivity among
shores. |
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