International Journal of Aquaculture, 2013, Vol.3, No.19, 105
-
114
http://ija.sophiapublisher.com
109
bands; the number of polymorphic bands and
percentage of polymorphism for all geographical
sample produced were Chennai 4 (16%), Nagapattinam 4
(16%),
Puddukottai 5 (17%) Ramanathapuram 3 (17%)
and Tuticorin 9 (49%). Genetic distance value was
high in Tuticorin sample than the other samples. Upgma
dendrogram produced 3 clades, in which Tuticorin
occupied the first clade, Pudukkottai-Ramanathapuram
second and Chennai-Nagapattinam third respectively
(
Figure 5).
Figure 5 Phylogeography of
P. semisulcatus
For
P. monodon
, 6
primers produced 126 bands,
Chennai sample showed 15 polymorphic bands (51%)
followed by Nagapattinam 12 (35%), Pudukottai11
(30%)
and Ramanathapuram 6 (16%). The genetic
similarity value was less in Chennai sample than the
other location sample. Upgma dendrogram showed
three clades for four geographical areas such Chennai
in first clade Nagapattinam second clade and
Pudukkottai –Ramanthapuram third clade (Figure 6).
Figure 6 Phylogeography of
P. monodon
2
Discussion
The understanding of population genetic structure is
of primary importance for the management and
conservation of genetic resources in exploited marine
organism (Hillis et al., 1996). Benzie (2000) revealed
little genetic variation over long distances than short
distances for many penaeid species. These limits vary
widely with species, habitats, local ocean conditions,
or historical events, and they may produce sufficient
chances for genetic variation (Palumbi, 1996). Molecular
genetic marker has a wide range of applications in
aquaculture research and for improvement of
aquaculture stocks (Hallerman and Beckmann, 1988.,
Poompuang and Hallerman, 1997; Liu and Cordes, 2004;
Chistiakov et al., 2006). Nuclear DNA marker only
provides high resolution to resolve the evolutionary
relationship and genetic diversity of the shrimp
(
Benzie, 2000; Dall, 2007; Vaseeharan et al., 2013).
Breeders will want to design future matings to avoid
inbreeding. Culturists may want to know whether the
offspring maintain the genetic characters of the wild
or founder population. In particular, they may want to
know whether genetic variability was maintained in
terms of number of polymorphic loci, number of
alleles per locus, and heterozygosity. Marker assisted
selection like growth rate; diseases resistant often
have high enough heritability to be improved using
classical selective breeding. The use of molecular
marker to address genetic identification and discrimination
of aquaculture stock, monitoring of inbreeding or
other changes in the genetic composition of the stocks
that may result from such phenomena as breeding
progarammes, founder events and genetic drift thereby
assisting selective breeding progarammes.
In the percent study,
F. indicus
species population, the
high number of polymorphic bands and percentage of
polymorphism producing in Chennai, followed by
Nagapattinam, Pudukkottai, Ramanathapuram, and
Tuticorin sample, which indicate among
F. indicus
population genetic diversity increseas Tuticorin to
Chennai, thus
F. indicus
population are highly
diverged toward northern direction of south east coast
of India. And phylogenetic relationship based on
genetic similarity, the Chennai and Nagapattinam
in one clade, Pudukkottai as separate clade,
Ramanathapuram–Tuticorin another clade, from the
above relationship show that
F. indicus
,
eventhough
polymorphism there in all population tested, this
populations could be considered three distinct stocks
those are Chennai-Nagapattinam, Pudukkottai, and
Ramanathapuam-Tuticorin. While analyzing
F. indicus
at reared condition using RAPD maker, concluding
rapid marker enough to assess genetic variation for the
establishment of marker-assisted selective breeding