Basic HTML Version
Journal of Mosquito Research, 2013, Vol.3, No.9, 65
-
70
ISSN 1927-646X
http://jmr.sophiapublisher.com
67
Table 1 COI Sequences of the
A. gambiae
complex
No.
Species
Accession number
Size (bp)
References
1
A. arabiensis
DQ465260
1115
Matthews et al., 2007
2
A. gambiae
DQ465336
1115
Matthews et al., 2007
3
A. bwambae,
AF222328
524
Linton et al., 2001
4
A. melas,
DQ792579
2303
Roe and Sperling, 2007
5
A. merus
JQ042681
1243
Kamali et al., 2012
6
A. quadriannulatus
DQ792581
2303
Roe and Sperling, 2007
Table 2 Estimates of evolutionary divergence between sequences
Species
1
2
3
4
5
6
A. arabiensis
A. gambiae
0.004
A. bwambae,
451.657
451.657
A. melas,
453.447
453.447
375.799
A. merus
613.053
613.228
607.133
613.227
A. quadriannulatus
453.627
453.627
376.139
0.020
619.379
The Maximum Likelihood method based on the
Tamura-Nei model (Tamura et al.,
2011),
Neighbor-Joining method (Roe and Sperling, 2007),
Minimum Evolution method (Tamura et al., 2004). All
the phylogenetic analyses were conducted in MEGA
software (http://www.megasoftware.net), version 5.0
(Kamali et al., 2012). Ancestral sequences were
inferred using web server: www.fastml.tau.ac.il. All
the positions containing gaps or missing data were
eliminated (complete deletion) from the dataset prior
to analysis. However, MEGA software also provides
alternatives to retain all such sites initially and
excluding them as necessary in the pair-wise
distance estimation (pairwise deletion option) or to
use the partial deletion (site coverage) as a
percentage. Evolutionary divergence between and
over all Sequences pairs of the
A. gambiae
complex were using the Maximum Composite
Likelihood model (Nei and Kumar, 2000).
Evolutionary analyses were conducted in MEGA 5
(Kamali et al., 2012).
Results and Discussion
The estimates of evolutionary divergence between
sequences of the
A. gambiae
complex are
presented in Table 2. The evolutionary divergence
is smallest between
A. arabiensis
and
A. gambiae
(0.004) and
A. melas
and
A. quadriannulatus
(0.02).
The divergence between other pairs of species was
much greater. From this result, it can be inferred that
A.
Arabiensis
and
A. gambiae
are the most closely
related taxa. This is in agreement with the
morphological,
behavioural,
and ecological
similarity between the two species described by the
work of Besansky et al (2003).
The nucleotide composition of each taxon in the
A.
gambiae
complex is presented in Figure 1. All the
members of this complex were all AT rich.
A.
gambiae
and
A. arabiensis
had the highest AT
composition with both having 39.0% thymine (T)
and 30.4% adenine (A), while
A. merus
had the
least among the complex with 28.8% thymine (T)
and 30.6% adenine (A). The nucleotide frequencies
are 29.68% (A), 36.77% (T), 16.92% (C), and
16.63% (G). There is more of thymine in the
sequences and less of cytosine. The frequency of
transversion rate is higher than that of transition
(Table 3). Transition rate occur more between
guanine and adenine while less between thymine
and cytosine. The transition/transversion rate
ratios are k
1
= 1000 (purines) and k
2
= 268.531
(pyrimidines). The overall transition/transversion
bias is R = 267.796, where R = [A×G×k
1
+
T×C×k
2
]/ [(A+G)×(T+C)].