Abstract:
Mitochondrial DNA (mtDNA) is an important genetic marker in population and
evolutionary biolog
y.
To
test the feasibility of
two
mitochondrial gene markers (COI and
Cytb)
for
Rhopalosiphum padi
, we collected
275 individuals
of the insect
species
from
15
locations, which cover most of the species’ distribution range in China,
and
analyzed
the
diversi
ty
of the two genes
. Seven COI haplotypes and 15 Cytb haplotypes were identified
by 13 and 36 polymorphic sites, respectively. Across the entire samples, the average
h
aplotype diversities (H
d
) of COI and Cytb were 0.491 and 0.607, and the nucleotide
divers
ities
(π) of COI and Cytb were 0.147
%
and 0.160%, respectively. Relatively low
levels of genetic diversity and genetic differentiation were observed among all
R. padi
populations
based on the two genes
. Moreover, parsimony networks of the COI and Cytb
haplotype
s of
R. padi
all supported a single clade. Alt
hough t
he nucleotide variation of
mitochondrial genes has been
used
in
other insect species, r
eviewing the recent literatures
on mitochondrial diversity in aphid species, we found that the population and
evolut
ionary biology of aphids including
R. padi
, could not be elucidated by analyzing
mtDNA alone, mostly because of the low genetic variation of mitochondrial genetic
markers among populations. We suggest the combined use of mtDNA and other genetic
markers, su
ch as microsatellites, to overcome the low genetic information provided by
mtDNA in evolutionary studies on aphid populations.
Keywords:
COI
,
Cytb
,
Gene markers, mtDNA
,
Population biology.
