Estimation of Sex−Related Genetic Diversity of Hagenia Abyssinica (Bruce) J.F.Gmel Using Random Amplified Polymorphic Dna (Rapd) Markers
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Date
2005-01
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Addis Ababa University
Abstract
The extent and distribution of sex-related and total genetic variation in Hagenia abyssinica
(Bruce) J.F. Gmel collected from four geographical regions of Ethiopia were analyzed using
random amplified polymorphic DNA (RAPD) markers for 80 plants representing 8 populations.
Three decamer primers generated a total of 19 polymorphic bands, across the 80 plant, with 6-7
bands per primer and an average of 6 bands. The amount of genetic variation within the
populations (HPop=0.32 for female populations; HPop=0.41 for male population; HPop=0.45 for
the entire population) and within the geographical regions (Hr=0.36 for female population; 0.51
for male population; 0.52 for the entire population) was low to moderate. Similarly, the average
genetic distance between populations (0.08 for female population; 0.09 for male population; 0.05
for the entire population) as well as between regions of sampling (0.05 for female population;
0.05 for male population; 0.02 for the entire population) was found to be low. The low genetic
variation may be due to the reduced population size of the tree species in Ethiopia because of
habitat change and indiscriminate clearing and over-cutting of trees for various purposes.
Partitioning of the genetic variation into between and within populations as well as between and
within regions of sampling revealed that 65% (for female population), 70% (for male population)
and 82% (for the entire population) of the variation was found within the populations whereas
75% (for female population), 88% (for male population) and 93%(for the entire population) of
the variation was found within regions. Cluster analysis of genetic distance estimates further
confirmed the low level of differentiation of the tree species both on population and regional
bases. The genetic diversity of male individuals was found to be greater than that of the female
individuals. The relatively lower genetic diversity in the female individuals may be due to the higher female mortality resulting from the added burden of fruit and seed setting in female
plants. Spearman’s correlation analysis showed that primer OPA-10 was found significantly
correlated with the male sex (locus OPA10-1: r = 0.395 significant at 0.01level) and hence
would help to identify the male sex. Discriminant analysis showed that this primer was also found
useful to identify which trees belong to which region.
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Biology