Allozyme Diversity and Population Structure in Korean Populations of Cymbidium goeringii (Orchidaceae) |
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Authors: | Mi Yoon Chung Myong Gi Chung |
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Institution: | (1) Department of Biology, Gyeongsang National University Chinju, 660-701 The Republic of Korea, KR |
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Abstract: | Cymbidium goeringii (Orchidaceae). Mean observed population heterozygosity (H
op=0.181), expected heterozygosity (H
eP=0.240), and total genetic diversity (H
T
=0.351) were all higher than average values for species with similar life-history characteristics. A considerable deficit
of heterozygotes relative to Hardy–Weinberg expectations was detected (77% of fixation indices were positive) with a mean
F
IS of 0.278. On average, 90% of the total genetic diversity was found within populations (mean G
ST
= 0.098). An indirect estimate of the number of migrants per generation (Nm=2.30, calculated from G
ST
, Nm=8.48, calculated from the frequencies of unique alleles) indicated that gene flow has been extensive in C. goeringii. Results of a spatial autocorrelation analysis based on allele frequencies of 16 populations revealed a trend with respect
to the distance classes (0<63 km, six significant positive values; beyond that distance, 12 significant negative values).
It is highly probable that C. goeringii has a history of relative large, continuous populations that had greater chance for gene movement among adjacent populations
via large numbers of small seeds, following the last Ice Age. Factors contributing to the high levels of genetic diversity
found within populations of C. goeringii include its large and continuous populations, its long-lived perennial habit, its widespread geographical distribution, and
its ability for relatively long distance seed movement by wind.
Received 18 June 1998/ Accepted in revised form 18 November 1998 |
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Keywords: | : Allozymes Cymbidium goeringii Gene flow Genetic diversity Population genetic structure |
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