Intl. J. of Mol. Evol. and Biodivers. 2015, Vol. 5, No. 1, 1-5
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2.2 Genetic distances and relatedness of coconut
forms
Genetic distances among the individuals based on the
Euclidean method revealed the highest distance of
SLT with all the rest of the individuals. The second
comparative coconut form SLGD, recorded closer
genetic distances with DL-SLYD. Furthermore, the
genetic distances within DL-SLYD were observed to
be low while comparatively higher distances were
observed between DL-SLYD and TL-SLYD. Also the
genetic distances among the individuals within
TL-SLYD were found to be comparatively high.
2.3 Phenetic tree
Figure 1 presents the dendrogram drawn by neighbour
joining method using Euclidean distances.
Figure 1 Phenetic tree drawn based on Euclidean distance
As expected from the genetic distances SLT separated
out as a single individual in the phenetic tree.
Secondly, three individuals of TLMS group formed a
clear separate cluster which was characterized by SSR
marker CAC65 D2 alleles. From the rest of
individuals six individuals of the seven within TLMT
group formed a separate cluster which was
characterized by homozygous D1 alleles of CAC65
and homozygous E3 alleles of CNZ12.
The rest of the individuals formed a larger group. Yet
in that DLMS1, TLMS2 DLMT6 and TLMT2 did
disperse from the main cluster and the results revealed
that there were missing values, rare alleles or different
allelic combinations in these four individuals. SLGD
separated with DLMS4 and DLMS5, the two latter
having several missing data points. Rest of the
individuals within the main cluster, included all
DL-SLYD and one individual from the TL-SLYD
group. This group was characterized by CAC65 D3
allele and CNZ G3 allele and included both tolerant
and susceptible individuals for
Aceria
mite infestation.
3 Discussion and Conclusions
The current study provides evidence for the presence
of a genetic structure within the Sri Lanka Yellow
Dwarf coconut population. The dwarf like group
possesses specific dwarf like morphological characters
described above and this group is genetically close
having common alleles. This dwarf like group is
genetically much similar to Sri Lanka Green Dwarf
and share similar alleles in all but one of the loci
observed in this study. As such this specific
microsatellite locus, CAC65 can be used to
distinguish SLGD from the DL-SLYD group.
Moreover, their morphological features resemble the
Malayan yellow dwarf coconuts, which is the most
widely known yellow dwarf coconut variety in the
world.
The tall like group on the other hand is
morphologically similar to several of the phenotypic
characters within the SLT coconut variety as described
in materials and methods. However, they do not
possess common alleles with the SLT coconuts
indicating that they are more an intermediate type and
mixed population despite being classified within
SLYD. Therefore, the evidence strongly suggests the
need for reclassification and purification of the
coconut form SLYD. Furthermore, the allelic
differences and the genetic distances are higher even
