Basic HTML Version
Journal of Mosquito Research, 2013, Vol.3, No.9, 65
-
70
ISSN 1927-646X
http://jmr.sophiapublisher.com
68
Figure 1 Nucleotide composition of the taxa of
A. gambiae
complex
Table 3 Maximum composite likelihood estimate of the pattern
of nucleotide substitution
A
T
C
G
A -
0.06
0.03
27.68
T 0.05
-
7.31
0.03
C 0.05
16.15
-
0.03
G 48.54
0.06
0.03
-
Figure 2 Molecular phylogenetic anaylsis by Maximum
Likelihood method
Evolutionary history was inferred using the Maximum
Likelihood method (Kamali et al., 2012) and is
presented in Figure 2.
A. arabiensis
and
A. gambiae
are the most recently evolved taxa among the
A.
gambiae
complex with an estimated divergence of less
than a million years. The ancestral node from which
the
A. gambiae
and
A. arabiensis
evolved from was
inferred to be
A. stephensi
, which shared the same
ancestral with
A. merus
over 293.93 million years ago.
A. merus
evolve from
A. Albitarsis
over 285 million
years ago.
A. melas
and
A. quadriannulatus
are also
recently evolved with an estimated divergence of less
than a million year ago. Their ancestry was inferred to
be from
A. deaneorum
, which shared the same
ancestor with
A. bwambae
.
Evolutionary history inferred using the Neighbor-Joining
method is presented in Figure 3. The topology of the tree
is similar to the tree built using the Maximum Likelihood
method. Notably,
A. arabiensis
and
A. gambiae
are on
the same clade in both trees. These species are the
most recently evolved, together with
A. melas
and
A.
quadriannulatus
, which also have an estimated
divergence time less than one million years.
A. melas
and
A. quadriannulatus
appear to have evolved from
A. deaneorum
, which shared the same ancestor with
A.
bwambae
. The species with the longest estimated
divergence times were
A. bwambae
(187 million years
ago) and
A. merus
(307 million year ago). In
agreement with the work of Besansky et al (2003),
Foley et al (1998), Morgan et al (2009),
A. gambiae
and
A. Arabiensis
were supported by our analysis as
monophyletic taxa.
Figure 3 Evolutionary relationships of taxa Neighbor-Joining
method
Proper understanding of the ancestral lineage of
A.
gambiae
complex species is essential for defining
proper taxonomy. Until recently, there has not been
detail molecular phylogenetic analysis of this complex.
Using phylogenetics tools, the present study provides
evidence of the ancestry, evolutionary history and
divergence of members of the complex. Furthermore,
it is also noted that
A. gambiae
and
A. arabiensis
shared the same ancestry, which may probably be
A.
stephensi
.
A. quadriannulatus
(non vector) and
A.
melas
(minor vector) were also found to have evolved
from a common ancestor. Our findings provide clues that
will aid understanding of phylogenetic relationships in this
complex, which would prove useful in vector control.