Journal of Genetics and Genomics
(Formerly Acta Genetica Sinica)
March 2007, 34(3): 196-213
Research Article
Research on the Karyotype and Evolution of Drosophila
melanogaster Species Group
Qiuhong Deng1, 2, Qingtao Zeng1,①, Yuanhuai Qian1, Chunxuan Li1, Yong Yang1
1. College of Life Science, Hubei University, Wuhan 430062, China;
2. College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
Abstract: Mitotic metaphase chromosomes of 34 species of Drosophila melanogaster species group were examined. Certain new
karyotypes were described for the first time, and their evolutionary and interspecific genetic relationships among 8 subgroups of
D. melanogaster species group were analyzed systematically. The results were as follows. The basic karyotype of elegans subgroup
was type A. The karyotypes of eugracilis subgroup, melanogaster subgroup, and ficusphila subgroup were all type C. The karyotypes of takahashii subgroup and suzukii subgroup were both type C and type D. The montium subgroup had six kinds of karyotypes:
types B, C, C’, D, D’, and E. The ananassae subgroup had three kinds of karyotypes: types F, G, and H. Thus, the melanogaster
species group was classified into five pedigrees based on the diversity of these karyotypes: 1) elegans; 2) eugracilis-melanogasterficusphila; 3) takkahashii-suzukii; 4) montium; 5) ananassae. The above-mentioned results in karyotypic evolution were consistent
with those of DNA sequence analysis reported by Yang except for the elegans subgroup and this subgroup was considered as the
ancestral subgroup. Karyotype analysis of the same drosophila from different isofemale lines indicated that the same Drosophila
from different places showed karyotypic variation which might be due to different geographical environment and evolutionary degree or interaction between the two factors.
Keywords: Drosophila; Drosophila melanogaster species group; karyotype; genetic relationships; evolution
Drosophila melanogaster species group belongs
to Drosophilidae, Drosophila genus, Sophophora
subgenus and includes about 180 species. Lemeunier
et al.[1] described each species of the D. melanogaster
species group in detail, and reported the karyotypes of
98 species of them. To date, only Ling et al.[2] described the karyotypes of drosophila in detail in China.
In their article entitled “Studies on the karyotypes of
some Chinese drosophila-flies”, they described the
karyotypes of 24 species of Drosophilidae from Yunnan and Guizhou, but only 12 species of the
D. melanogaster species group were studied. These
were: D. malerkotliana, D. melanogaster, D. takahashii, D. suzukii, D. pulchrella, D. auraria, D. triauraria, D. kikkawai, D. trapezifrons, D. parvula, D. lini,
and D. sp. like trilutea. Recently Qian et al. [3] reported the karyotypic diversity of 40 species of Drosophila melanoganster species group in China. In this
research, third instar larvae of drosophila were chosen
as experimental materials and the metaphase chromosomes from 34 species of D. melanogaster species
group were studied. Through analysis of karyotypes
of the same species from different geographical distribution, the geographical difference, the evolution-
Received: 2006-05-12; Accepted: 2006-06-16
This work was supported by National Natural Sciences Foundation of China (No. 39930100) and International Collaborative Project
of Hubei Provincial Department of Education (No. G200610001).
① Corresponding author. E-mail: [email protected].
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Qiuhong Deng et al.: Research on the Karyotype and Evolution of Drosophila melanogaster Species Group
ary relationships, and interspecific genetic relationships of the 34 species of D. melanogaster species
group were clarified.
1
Materials and Methods
1. 1
Materials
All samples of 34 species were collected from
Table 1
197
mainland China and were identified by Professor
Qian[3]. All animals were fed and maintained in the
Genetics Lab of College of Life Science in Hubei
University. The third instar larvae of drosophila were
selected as experimental materials. Table 1 shows the
species name, collection location, and karyotypic
composition of 34 species of D. melanogaster species
group.
34 species of the melanogaster species group: species name, collection location, and karyotypic structure
Species name
D. ananassae
Yunnan
D. bipectinata
Tibet
D. malerkotliana
Tibet
D. parabipectinata
Hainan
D. pseudoananassae
Hainan
D. elegans
Hainan
D. eugracilis 1
Hainan
D. eugracilis 2
Hainan
D. eugracilis 3
Tibet
D. ficusphila
Guangdong
Hainan
D. melanogaster
D. simulans
Hainan
D. auraria
Henan
D. kikkawai
Hainan
D. lini
Yunnan
D. leontia
Yunnan
D. barbarae
Tibet
D. constricta
Guangdong
D. cheni sp.nov*
Guangdong
D. trapezifrons
Guangxi
D. tani
Guangdong
D. huaping sp.nov*
Guangxi
D. baimaii
Tibet
D. pseudobaimaii
Tibet
D. parvula
Hainan
D. jambulina 1
Hainan
D. jambulina 2
Tibet
D. suzukii
Henan
D. biarmipes
Hainan
D. pulchrella
Henan
D. chayu sp.nov*
Tibet
D. lucipennis
Guangdong
D. giriensis
Guangdong
D. takahashii
Hainan
D.curveaedeagus sp.nov* Tibet
D. prostipennis
Guangdong
D. trilutea
Hubei
M = metacentric; sm = submetacentric; st
ported soon).
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Sex chromosome
Autosome
X
Y
Ⅱ
Ⅲ
Ⅳ
Ⅴ
Ⅵ
Hekou
M
sm
M
M
M
Xiachayu
M
M
M
M
M
Xiachayu
M
M
M
M
M
Maoyang
M
M
M
M
M
Jianfengling
M
st
M
M
M
M
Dongshanling
st
st
T
T
T
T
D
Jianfengling
T
T
M
M
D
Lingshui
T
T
M
M
D
Xiachayu
T
T
M
M
D
Dinghushan
T
T
M
M
D
Wuzhishan
T
M
M
M
D
Hudiegu
T
M
M
M
D
Baotianman
T
T
M
M
D
Bawangling
T
T
M
M
M
Malipo
T
st
M
M
T
Hekou
T
M
M
M
D
Xiachayu
T
T
M
M
D
Dinghushan
T
st
M
M
Dinghushan
T
T
M
M
T
Huaping
st
sm
M
M
T
Dinghushan
T
st
M
M
D
Huaping
T
T
M
M
T
Xiachayu
T
T
M
M
D
Chayu
T
T
M
M
D
Jianfengling
st
st
M
M
D
Maoyang
T
M
M
M
D
Xiachayu
T
T
M
M
D
Jigongshan
T
T
M
M
Dr
Sanya
T
st
M
M
D
Jigongshan
T
T
M
M
Dr
Xiachayu
T
T
M
M
Dr
Chebaling
T
st
M
M
Dr
Chebaling
T
T
M
M
D
Wuzhishan
T
T
M
M
Dr
Xiachayu
T
st
M
M
Dr
Dinghushan
T
T
M
M
D
Wuhan
T
T
M
M
Dr
= subtelocentric; T = telocentric; D = dot; Dr = rod-like dot; * new species (will be re-
Collection location
198
1. 2
Journal of Genetics and Genomics
Methods
The flies collected from open country were
stored in a glass vial that contained cornmeal Drosophila medium and was placed in incubators at 20 ± 2
℃ under continuous light. Neuroblasts were dissected from third instar larvae in Ringer’s solution,
treated with 0.065 mg/mL of colchicine solution for
40 min to 1 h. Hypotonic treatments were made with
0.075 mol/L KCl solution for 40 min. The neuroblasts
were then fixed with Carnoy solution for 30 to 40 min,
followed by knocking on the slide. The slides were
dried at a slow pace on an alcohol burner. After several hours, the slide was stained with Giemsa solution
(10%, pH 6.8) for 1.5 h at 25℃, washed in water, and
air-dried. Metaphase images were taken under an
Table 2
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Vol.34 No.3 2007
Olympus BH-2 microscope. About 30 metaphase plates
in 10 individuals were observed for each species.
2
2. 1
Results
Classification of karyotypes
According to Lemeunier et al., there were 18
kinds of chromosomal karyotypes in the melanogaster
species group: types A, A’, B, C, C’, C’’, D, D’, E, E’,
E’’, F, G, H, I, J, K, and L [1]. 34 species with 10 kinds
of karyotypes were studied: types A, B, C, C’, D, D’,
E, F, G, and H. These karyotypes are illustrated in
Table 2. The diagrams all corresponded to the karyotypes of female flies (i.e. XX). The metaphase forms
of Y chromosomes are listed separately in the table.
Metaphase chromosomes of the melanogaster species group
Karyotypes
A :2n=12
No. of the photographs
85–86
Species name
D. elegans
Subgroupa
ele
Shape of the Yb
J
B :2n=6
36–37
D. constricta
mon
J
C :2n=8
20–21
46–47
34–35
58–59
79–84
77–78
66–67
52–53
54–55
32–33
16–17
72–73
48–49
18–19
44–45
D. auraria
D. baimaii
D. barbarae
D. biarmipes
D. eugracilis 1, 2, 3
D. ficusphila
D. giriensis
D. jambulina 1
D. jambulina 2
D. leontia
D. melanogaster
D. prostipennis
D. pseudobaimaii
D. simulans
D. tani
mon
mon
mon
suz
eug
fic
tak
mon
mon
mon
mel
tak
mon
mel
mon
R
R
R
J
R
R
R
V
R
V
V
R
R
V
J
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Qiuhong Deng et al.: Research on the Karyotype and Evolution of Drosophila melanogaster Species Group
Karyotypes
C’ :2n=8
No. of the photographs
50–51
D :2n=8
Species name
D. parvula
Subgroupa
mon
199
(Table 2 continued)
Shape of the Yb
J
D’ :2n=8
62–63
38–39
70–71
42–43
24–31
64–65
60–61
56–57
68–69
74–76
40–41
D. chayu sp. nov
D. cheni sp. nov
D. curveaedeagus sp. nov
D. huaping sp. nov
D. lini
D. lucipennis
D. pulchrella
D. suzukii
D. takahashii
D. trilutea
D. trapezifrons
suz
mon
tak
mon
mon
suz
suz
suz
tak
tak
mon
R
R
J
R
J
J
R
R
R
R
J
E :2n=8
22–23
D. kikkawai
mon
R
F :2n=8
1–2
D. ananassae
ana
J
G :2n=8
3–4
5–6
7–8
D. bipectinata
D. malerkotliana
D. parabipectinata
ana
ana
ana
V
V
V
H :2n=10
9–15
D. pseudoananassae
ana
J
a
List of abbreviations corresponding to the subgroups. ananassae, ana; elegans, ele; eugracilis, eug; ficusphila, fic; melanogaster,
mel; montium, mon; suzukii, suz; takahashii, tak; bLetters (J, R, V) correspond to the shape of the Y chromosome: J for a submetacentric or subtelocentric chromosome; R for a telocentric chromosome; and V for a metacentric chromosome.
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Journal of Genetics and Genomics
Type A: 2n = 12 (4R, 1J, 1D), comprising 4 pairs
of rod-shaped telochromosomes, a pair of sex chromosomes (X = J), and a pair of dot-like chromosome
Ⅵ.
2.2.1
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Vol.34 No.3 2007
The ananassae subgroup
The karyotypes of ananassae subgroup are
shown in Figs. 1–15. Four species of this subgroup
except D. pseudoananassae had a diploid number of 8
Type B: 2n = 6 (2V, 1R), comprising 2 pairs of
V-shaped metacentric autosomes and a pair of sex
chromosomes (X = R).
Type C: 2n = 8 (2V, 1R, 1D), comprising 2 pairs
of V-shaped autosomes, a pair of sex chromosomes
(X = R), and a pair of dot-like chromosome Ⅳ.
Type C’: 2n = 8 (2V, 1J, 1D), comprising 2 pairs
of V-shaped autosomes, a pair of sex chromosomes
(X = J), and a pair of dot-like chromosome Ⅳ.
Type D: 2n = 8 (2V, 2R), comprising 2 pairs of
V-shaped autosomes, a pair of sex chromosomes (X =
R), and a pair of rod-shaped chromosome Ⅳ.
Type D’: 2n = 8 (2V, 1J, 1R), comprising 2 pairs
of V-shaped autosomes, a pair of sex chromosomes
(X = J), and a pair of rod-shaped chromosome Ⅳ.
Type E: 2n = 8 (3V, 1R), comprising 3 pairs of
V-shaped autosomes, and a pair of sex chromosomes
(X = R).
Type F: 2n = 8 (4V), comprising 4 pairs of
V-shaped chromosomes with metacentric X (X = V).
Sex chromosomes and chromosome 4 were of the
chromosomes, comprising 4 pairs of V-shaped chromosomes. There were minor differences among the
four species in the form of Y chromosomes.
D. ananassae had a submetacentric (J-shaped) Y
chromosome while each of the other three had a
metacentric (V-shaped) Y chromosome.
D.
pseudoananassae
displayed
karyotypic
polymorphism. Its chromosome number varied from 7
to 10. The chromosomes of this species were all
metacentric. It had six kinds of kayotypes: 7 = 5 + 2,
7 = 6 + 1, 8 = 6 + 2, 9 = 6 + 3, 10 = 5 + 5, and 10 = 6
+ 4, that is, the number of chromosomes equals the
number of larger V-shaped chromosomes with two
clearly separated chromatids plus the number of
smaller V-shaped ones with two fused chromatids. 56
mitotic plates of 7 individuals for this species were
examined and the percentage of each karyotype
among all karyotypes was counted (Table 3).
2.2.2
The melanogaster subgroup
D. melanogaster and D. simulans were both col-
same length, slightly shorter than chromosomes Ⅱ
lected from the Hainan Province. Their karyotypes are
and Ⅲ.
illustrated in Figs. 16–19. The common chromosome
Type G: 2n = 8 (4V), comprising 4 pairs of
V-shaped chromosomes (X = V). Sex chromosomes
were the longest of the four pairs, followed by chro-
composition was 2n = 8 (2V, 1R, 1D), comprising 2
mosome Ⅱ, Ⅲ, and Ⅳ.
autosomes.
Type H: 2n = 10 (5V), comprising 2 pairs of
V-shaped autosomes, a pair of sex chromosomes (X =
V), and 2 pairs of small V-shaped autosomes with
fused chromatids.
2. 2
Description of the karyotypes
pairs of V-shaped autosomes, a pair of sex chromosomes (X = R, Y = V), and a pair of small dot-like
2.2.3
The montium subgroup
2.2.3.1 auraria complex
The karyotype of D. auraria from Henan is 2n =
8 (2V, 1R, 1D). Both X and Y chromosomes were rod
shaped. The Y chromosome was slightly shorter than
In this research, the metaphase chromosomes of
34 species in D. melanogaster species group were
examined, and the chromosomal karyotypes of these
the X chromosome (Figs. 20–21).
2.2.3.2 kikkawai complex
species are shown in Figs. 1-86.
four species in kikkawai complex.
Figs. 22–35 show metaphase configurations of
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Qiuhong Deng et al.: Research on the Karyotype and Evolution of Drosophila melanogaster Species Group
Figs. 1-15
201
Metaphase chromosomes of Drosophila
1: D. ananssae♀; 2: D. ananassae♂; 3: D. bipectinata♀; 4: D. bipectinata♂; 5: D. malerkotliana♀; 6: D. malerkotliana♂; 7: D.
parabipectinata♀; 8: D. parabipectinata♂; 9-15. D. pseudoananassae 9: 7=5+2; 10: 7=6+1; 11: 8=6+2; 12: 9=6+3; 13: 9=6+3; 14:
10=6+4; 15: 10=5+5.
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202
Figs. 16-30
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Vol.34 No.3 2007
Metaphase chromosomes of Drosophila
16: D. melanogaster♂; 17: D. melanogaster♂; 18: D. simulans♀; 19: D. simulans♂; 20: D. auraria♀; 21: D. auraria♂; 22: D.
kikkawai♀; 23: D. kikkawai♂; 24: D. lini♀ (2n=8); 25: D. lini♀ (2n=8+1); 26: D. lini♀ (2n=8+2); 27: D. lini♀ (2n=8+3); 28:
D. lini♂ (2n=8); 29: D. lini♂ (2n=8+1); 30: D. lini♂ (2n=8+2).
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Qiuhong Deng et al.: Research on the Karyotype and Evolution of Drosophila melanogaster Species Group
Figs. 31-45
203
Metaphase chromosomes of Drosophila
31: D. lini♂ (2n=8+3); 32: D. leontia♀; 33: D. leontia♂; 34: D. barbarae♀; 35: D. barbarae♂; 36: D. constricta♀; 37: D. constricta♂; 38: D. cheni sp.nov♀; 39: D. cheni sp.nov♂; 40: D. trapezifrons♀; 41: D. trapezifrons♂; 42: D. huaping sp.nov♀; 43:
D. huaping sp.nov♂; 44: D. tani♀; 45: D. tani♂.
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204
Figs. 46-60
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Vol.34 No.3 2007
Metaphase chromosomes of Drosophila
46: D. baimaii♀; 47: D. baimaii♂; 48: D. pseudobaimaii♀; 49: D. pseudobaimaii♂; 50: D. parvula♀; 51: D. parvula♂; 52: D.
jambulina 1♀; 53: D. jambulina 1♂; 54: D. jambulina 2♀; 55: D. jambulina 2♂; 56: D. suzukii♀; 57: D. suzukii♂; 58: D. biarmipes♀; 59: D. biarmipes♂; 60: D. pulchrella♀.
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Qiuhong Deng et al.: Research on the Karyotype and Evolution of Drosophila melanogaster Species Group
Figs. 61-75
205
Metaphase chromosomes of Drosophila
61: D. pulchrella♂; 62: D. chayu sp.nov♀; 63: D. chayu sp.nov♂; 64: D. lucipenni♀ (2n=8); 65: D. lucipennis♂ (2n=7); 66: D.
giriensis♀; 67: D. giriensis♂; 68: D. takahashii♀; 69: D. takahashii♂; 70: D. curveaedeagus sp.nov♀; 71: D. curveaedeagus
sp.nov♂; 72: D. prostipennis♀; 73: D. prostipennis♂; 74: D. trilutea♀ (XX, 2n=8); 75: D. trilutea♂ (XY, 2n=8).
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206
Journal of Genetics and Genomics
Figs. 76-86
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Metaphase chromosomes of Drosophila
76: D. trilutea♀ (XXY, 2n=9); 77: D. ficusphila♀; 78: D. ficusphila♂; 79: D. eugracilis 1♀; 80: D. eugracilis 1♂; 81: D. eugracilis 2♀; 82: D. eugracilis 2♂; 83: D. eugracilis 3♀; 84: D. eugracilis 3♂; 85: D. elegans♀; 86: D. elegans♂.
Table 3
The percentage of each kind of karyotype of D.pseudoananassae
Karyotypes
7=5+2
7=6+1
8=6+2
9=6+3
10 = 6 + 4
10 = 5 + 5
Mitotic figures
4
4
16
16
10
6
Percentage
7.1%
7.1%
28.6%
28.6%
18%
10.6%
The chromosome number of D. kikkawai from
Hainan was 2n = 8 (3V, 1R) (X = R, Y = R). The two
fourth chromosomes were V-shaped and equal in
length in males, whereas one of the two was
rod-shaped and half the length of the other in females.
Moreover, this is the first report of its kind.
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Qiuhong Deng et al.: Research on the Karyotype and Evolution of Drosophila melanogaster Species Group
D. lini from Yunnan Province had a karyotype of
2n = 8 + D (D = 0, 1, 2, 3). D meant dot-like B chromosomes. The number of normal chromosomes was
2n = 8 (2V, 2R) (X = R, Y = J). Sex chromosomes and
the fourth chromosomes were equal in length. The
number of B chromosomes varied from 1 to 3. Both
males and females had four kinds of karyotypes (2n =
8, 2n = 8 + 1, 2n = 8 + 2, 2n = 8 + 3).
D. leontia from Yunnan had a chromosomal
composition of 2n = 8 (2V, 1R, 1D) (X = R, Y = V).
D. barbarae from Tibet had a karyotype of 2n =
8 (2V, 1R, 1D) (X = R, Y = R). The fourth chromosomes were dot microchromosomes.
2.2.3.3 trapezifrons complex
The trapezifrons complex was newly established
by D. constricta, D. cheni sp.nov, D. trapezifrons, D.
207
somes (2V, 1R, 1D) with telocentric (rod-shaped) X
and Y (Figs. 46–47). X and Y were the similar in
length. Y chromosome was heterochromatic.
D. pseudobaimaii from Tibet had an identical
karyotype of 2n = 8 (2V, 1R, 1D) as D. baimaii (Figs.
48–49).
D. parvula from Hainan possessed 2n = 8 chromosomes (2V, 1J, 1D) with subtelocentric (J-shaped)
X and Y (Figs. 50–51). The dot was barely recognizable.
Figs. 52–55 show metaphase configurations of
two isofemale lines of D. jambulina. In the two lines,
the chromosome number were both 2n = 8 (2V, 1R,
1D). D. jambulina 1 included a pair of sex chromosomes (X = R, Y = V), while sex chromosomes of D.
jambulina 2 were both rod-shaped (X = R, Y = R).
huaping sp.nov, and D. tani. Their karyotypes are
2.2.4
shown in Figs. 36-45.
Guangdong was 2n = 6 (2V, 1R), composed of 2 pairs
The karyotype of D. suzukii (2n = 8: 2V, 2R)
from Henan is shown in Figs. 56–57. Chromosome X
was telocentric and Y was a very short rod (X = R, Y
of V-shaped autosomes and a pair of sex chromo-
= R). Chromosome Ⅱ was twice as long as that of
somes (X = R, Y = J). It lost a pair of the free fourth
Chromosome Ⅲ. Two chromatids of the telocentric
chromosomes.
fourth microchromosomes were separate and the
fourth chromosome resembled a pair of small butterflies.
D. biarmipes from Hainan had a karyotype of 2n
= 8 (2V, 1R, 1D). Y chromosome was J-shaped (Figs.
58–59).
The karyotype of D. pulchrella from Henan was
identical to that of D. suzukii (2n = 8: 2V, 2R) (X = R,
Y = R) (Figs. 60–61).
D. chayu sp.nov from Tibet showed 2n = 8
chromosomes (2V, 2R) with telocentric X and Y. The
form of the fourth chromosomes of D. chayu. sp. nov
was the same as that of D. suzukii (Figs. 62–63).
D. lucipennis from Guangdong had a karyotype
of 2n = 8 (2V, 2R) in females and 2n = 7 in males. Y
chromosome was J-shaped. The fourth chromosomes
of D. lucipennis were small and telocentric like those
of D. suzukii. The male lost a free fourth chromosome
(Figs. 64–65).
The chromosome number of D. constricta from
D. cheni sp.nov from Guangdong had a karyotype of 2n = 8 (2V, 2R) (X = R, Y = R). The fourth
chromosomes were a pair of short heterochromatic
rod autosomes.
D. trapezifrons from Guangxi possessed 2n = 8
(2V, 1J, 1R). Both X and Y were J-shaped chromosomes. The rod-shaped fourth chromosomes were also
short and heterochromatic.
D. huaping sp.nov from Guangxi had a similar
karyotype 2n = 8 (2V, 2R) with D. cheni sp.nov.
D. tani from Guangdong had a karyotype 2n = 8
(2V, 1R, 1D) similar to D. melanogaster. X chromosome was rod-shaped while Y chromosome was
J-shaped. The fourth chromosomes were slightly
stained dot chromosomes.
2.2.3.4 Other species of the montium subgroup
D. baimaii from Tibet showed 2n = 8 chromowww.jgenetgenomics.org
The suzukii subgroup
208
2.2.5
Journal of Genetics and Genomics
The takahashii subgroup
D. giriensis from Guangdong had a diploid
number of 8 chromosomes (2n = 8: 2V, 1R, 1D) with
telocentric X and Y. The Y chromosome was slightly
shorter than the X chromosome (Figs. 66–67).
D. takahashii from Hainan had a karyotype of 2n
= 8 (2V, 2R), comprising 2 pairs of large metacentric
(V-shaped) autosomes, sex chromosomes (X = R, Y =
R), and 1 pair of small rod-shaped fourth chromosomes (Figs. 68–69).
D. curveaedeagus sp.nov from Tibet (2V, 2R)
had 2 pairs of V-shaped autosomes, sex chromosomes
(X = R, Y = J), and a pair of rod microchromosomes
(Figs. 70–71). Y chromosome had a clear subtelocentric constriction.
D. prostipennis from Guangdong (2V, 1R, 1D)
had 2 pairs of V-shaped autosomes with different
lengths, sex chromosomes (X = R, Y = R), and a pair
of dot-like fourth chromosomes (Figs. 72–73).
D. trilutea from Hubei had strange karyotypes: (i)
2n = 8 (XX, XY) with 2 pairs of V-shaped autosomes,
a pair of sex chromosomes (X = R, Y = R), and a pair
of rod-shaped microchromosomes; (ii) 2n = 9 (XXY)
with 2 pairs of V-shaped autosomes, three sex chromosomes (X = R, X = R, Y = R), and a pair of
rod-shaped microchromosomes (Figs. 74-76). This
was different from previously reported as 2n = 6 (XX,
XY) [1] or 2n = 8 (XX, XY)[2].
2.2.6
The ficusphila subgroup
遗传学报
Vol.34 No.3 2007
too small and unclear to be recognized, whereas those
of D. eugracilis 3 were clearly visible (Figs. 79–84).
2.2.8
The elegans subgroup
The chromosomes of D. elegans from Hainan
differed from those of all other members in the
melanogaster species group. Figs. 85–86 showed its
karyotype, containing 4 pairs of telocentric autosomes
and a pair of sex chromosomes (X = J, Y = J), and a
pair of dot-like 6th chromosomes.
3
Discussion
3. 1
Karyotypic variation of the same species
from different geographic distributions
34 species of the D. melanogaster species group
were studied. Three lines of D. eugracilis from different geographical locations were studied: D. eugracilis 1 from Jianfengling in Hainan Province,
D. eugracilis 2 from Lingshui in Hainan Province,
and D. eugracilis 3 from Xiachayu in Tibet. All of
them had a similar karyotype with a pair of dot-like
fourth chromosomes with variable degrees of staining.
The fourth chromosomes of D. eugracilis 1 were so
small and faintly stained that its chromosome number
could almost be thought as 2n = 6. The fourth chromosomes of D. eugracilis 2 and D. eugracilis 3 were
progressively more conspicuous. These data suggested that D. eugracilis from different strains had an
almost invariable karyotype.
Two lines of D. jambulina (lines 1 from Hainan
D. ficusphila from Guangdong had a classical
karyotype of 2n = 8 (2V, 1R, 1D) which is shown in
Figs. 77–78. The Y chromosome was slightly shorter
than the X chromosome.
2.2.7
The eugracilis subgroup
D. eugracilis 1 from Hainan, D. eugracilis 2
from Hainan and D. eugracilis 3 from Tibet possessed
2n = 8 (2V, 1R, 1D). There were minor differences in
the fourth chromosomes. The dot-like fourth chromosomes of D. eugracilis 1 and D. eugracilis 2 were
Province, and lines 2 from Tibet) were studied. D.
jambulina 1 had a karyotype of 2n = 8 (2V, 1R, 1D)
with 2 pairs of V-shaped autosomes, a pair of sex
chromosomes (X = R, Y = V), and a pair of dot-like
fourth chromosomes. D. jambulina 2 had a similar
karyotype with D. jambulina 1 but Y chromosome
was rod shaped (X = R, Y = R). Thus, it can be concluded that D. jambulina 2 should be placed in an
earlier period than D. jambulina 1 during the course
of evolution.
www.jgenetgenomics.org
Qiuhong Deng et al.: Research on the Karyotype and Evolution of Drosophila melanogaster Species Group
In addition, an extensive karyotypic variation
among the different geographical distributions have
been observed in D. malerkotliana, D. lini, D. kikkawai, D. auraria, D. suzukii, D. trapezifrons, D.
biarmipes, D. pulchrella, D. takahashii, and D. pseudoananassae after comparison with previous results.
The karyotypic diversity in different geographical
distributions was reflected in the form and structure of
chromosomes, and not in chromosome number except
those having B chromosomes.
3. 2
2n = 6 or 2n = 8
It was found that D. eugracilis (from Hainan and
Tibet), D. baimaii (from Tibet), D. barbarae (from
Tibet), and D. prostipennis (from Guangdong) had a
similar karyotype of 2n = 8 (2V, 1R, 1D) with 2 pairs
of V-shaped autosomes, 1 pair of sex chromosomes,
and 1 pair of dot-like autosomes. However, Lemeunier et al.[1] reported that the four species had a
karyotype of 2n = 6 (2V, 1R) with 2 pairs of V-shaped
autosomes and 1 pair of sex chromosomes. The difference between 2n = 6 (2V, 1R) and 2n = 8 (2V, 1R,
1D) was the absence or presence of a pair of dot-like
fourth chromosomes.
As stated above, karyotypic variations were
found in the same species from different geographical
distributions, and the variation was in the form and
structure of chromosomes, but chromosome number
was invariable. So the significant difference in the
number of chromosomes could not be explained by
the karyotypic variation of the geographical distribution. Ward[4] reported that chromosomal fusion or
translocation, which led to chromosomal evolution,
caused gene transfer and change of chromosome
number among different lines of the same species.
Reduction, rather than increase, of chromosome
number was more likely to have occurred in Drosophilidae. By chromosomal fusion or translocation, 6
chromosomes that Lemeunier et al.[1] described might
have been derived from 8 chromosomes, from species
closely related to those that have been studied, sugwww.jgenetgenomics.org
209
gesting that Lemeunier’s species[1] might have been
evolu- tionarily more advanced than those that were
studied. Other possibility is that an error occurred
during slides or images processing that led to the loss
of 2 chromosomes, in which case the chromosome
number in D. eugracilis, D. baimaii, D. barbarae, and
D. prostipennis should be 2n = 8, not 2n = 6. Similarly, the theory proposed by Ward[4] might also explain the karyotypic differences between the species
studied here, that is, D. parvula (2n = 8: 2V, 1J, 1D,
from Hainan), D. lucipennis (2n = 8 or 7: 2V, 2R,
from Guangdong), and D. trilutea (2n = 8 or 9: 2V,
2R, from Hubei) and those closely related species (2n
= 6: 2V, 1R) that Lemeunier et al.[1] reported.
The karyotypic variations exhibited in the same
species from different places, whether chromosomal
form and structure or number, might be related to environmental difference, chromosomal evolution, or
the interaction between the two factors.
3. 3
B chromosomes in D. lini, D. malerkotliana,
and D. pseudoananassae
Many organisms have extrachromosomes. There
are significant differences between normal chromosomes (A chromosomes) and extrachromosomes (B
chromosomes). B chromosome was first found and
coined by Longly (1972) and Randolph (1928). So far,
B chromosomes have been found in about 1,300 kinds
of plants and 500 kinds of animals[5]. Hatsumi and
Clyde[6,7] found B chromosomes in D. albomicans for
the first time. Thereafter, Ramachandra (1985, 1987),
Hastumi (1987), and Ling (1991) reported the presence of B chromosomes in D. albomicans in Thailand,
-
Burma, Malaysia, and Kunming populations[8 11].
Professor Qian[12] also reported B chromosomes in D.
albomicans in Wuhan population. The characteristics
of the B chromosomes are that they are mostly dot
shaped and their number varies in different individuals, cells, and tissues. It was believed that D. albomicans was the best material for observing B chromosomes, studying its source and polymorphism, but
now we found D. lini also had B chromosomes.
210
Journal of Genetics and Genomics
The karyotype of D. lini from Yunnan was 2n = 8
+ D (D = 0, 1, 2, 3). A chromosomes (2V, 2R) consisted of 2 pairs of V-shaped autosomes, sex chromosomes, and a pair of rod-shaped fourth chromosomes.
In this species, both X and Y chromosomes were
similar in length to the fourth chromosomes. B chromosome was heterochromatic and dot like. Whether
males or females of D. lini had four karyotypes, that
is, 2n = 8, 2n = 9, 2n = 10, and 2n = 11. The number
of B chromosomes varied in different individuals of
the same species and different cells of the same individual. It was found that B chromosomes occurred in
D. lini for the first time, so the origin of them was
obscure. B chromosomes of D. lini might have been
derived from chromosomal rupture or recombination
in the course of long-term evolution in a continuously
changing environment.
Ling et al.[2] reported the karyotype of
D. malerkotliana from Kunming was 2n = 8 + D (D =
1), which was composed of 4 pairs of metacentrics
and a heterochromatic dot. The D. malerkotliana from
Tibet that was studied had a karyotype of 2n = 8 (4V).
It had no extrachromosomes but secondary constrictions on the fourth and X chromosomes were observed. The phenomenon implied that D. malerkotliana from Tibet appeared earlier than those from
Kunming in the course of evolution.
D. pseudoananassae from Jianfengling in
Hainan Province displayed karyotypic polymorphism.
The chromosome number varied from 7 to 10. All
chromosomes were metacentric. It was very possible
that D. pseudoananassae from Hainan had B chromosomes and their number was unstable. But the real
cause of karyotypic polymorphism in this species was
unknown and needed further studies.
Type C or type D
In this research, the karyotypes of
D. curveaedeagus sp.nov, D. takahashii, D. trilutea,
D. chayu sp.nov, D. lucipennis，D. pulchrella, and
D. suzukii were all type D (2n = 8: 2R, 2V). Lemeunier
Vol.34 No.3 2007
et al.[1] reported that D. takahashii had type C and C’’
karyotypes. The karyotype of D. trilutea and D. lucipennis were both type B. The karyotypes of D. pulchrella and D. suzukii were both type C. Qian et al.[3]
reported that D. sp. like takahashii (i.e. D.
curveaedeagus sp.nov), D. takahashii and D. trilutea
all had a karyotype of type C. D. sp. like nyinyii（i.e.
D. chayu sp.nov）and D. suzukii both had a karyotype
of type C’’’. The karyotypes of D. lucipennis and D.
pulchrella were both type C’’’’. The fourth chromosomes were absent in type B and type C”. The fourth
chromosomes were dot like in type C, C’, C’’’, and
C’’’’. The fourth chromosomes were rod shaped in
type D. The fourth chromosomes of the
above-mentioned seven species were all rod-like dot
(Dr) [13]. The seven species were put in type D, which
indicated that their fourth chromosomes were small
rod-like chromosomes.
3. 5
Discovery of primitive karyotype example
The karyotype of D. elegans is 2n = 12 (4R, 1J,
1D). It was obviously different from the karyotype of
D. elegans (type A’: 2n = 10) that Bock and Wheeler
reported[14]. The remarkable difference between them
was that the former had dot-like sixth chromosomes
while the latter had only 5 pairs of rods. Lemeunier et
al.[15] reported that the primitive karyotype (i.e. type
A) of D. melanogaster species group was 2n = 12
with 5 pairs of rod-shaped chromosomes and 1 pair of
dot-like sixth chromosomes. However, examples of
type A have not been found to date. Therefore, the
karyotype of D. elegans fulfills the example of a
primitive karyotype in the D. melanogaster species
group.
3. 6
3. 4
遗传学报
Analyses of interspecific genetic relationships and evolutionary relationships
among 8 subgroups
The karyotypes of 33 species except D. elegans
in D. melanogaster species group (Drosophila
(Sophophora), Drosophilidae) showed a clear-cut
www.jgenetgenomics.org
Qiuhong Deng et al.: Research on the Karyotype and Evolution of Drosophila melanogaster Species Group
211
characteristic of this species group. They all included
vided the melanogaster species group into five clus-
2 pairs of almost the same-sized metacentric chromo-
ters using rDNA sequences analysis: ananassae, mon-
somes (Ⅱ, Ⅲ). Chromosome Ⅱ was the larger of the
tium, ficusphila-elegans, (takkahashii-suzukii)-eug-
two pairs. The characteristic offered a genetic proof
racilis and melanogaster. By analyzing the Amy
that they maintained interspecific genetic relation-
mul- tigenes, Inomata et al.[20] reported that the
ships during karyotypic evolution. D. elegans (2n =
ananassae subgroup branched off followed by eug-
12), D. constricta (2n = 6), and D. pseudoananassae
racilis sub- group and the others were divided into
(with 7–10 chromosomes) had different number of
two large branches, but certain subgroups were in
chromosomes from the other 31 species which had a
between. By analyzing P elements, Clark et al.[21] con-
diploid number of 8 chromosomes (2n = 8). The 31
cluded that melanogster, ficusphila, elegans, takaha-
species all included 2 pairs of V-shaped autosomes.
shii, suzukii, and eugracilis differentiated at the same
The karyotypic differences among the 31 species were
time after ananassae and montium were differentiated
the form and size of, as well as, the amount and dis-
success- sively. Goto and Kimura[22] thoroughly ana-
tribution of heterochromatin on the sex and fourth
lyzed COI and Gpdh genes and proposed that
chromosomes. This resulted from different mecha-
ananassae differ- entiated at first, followed by montium,
nisms of chromosomal recombination during evolution. The species in the ananassae subgroup were
very special among the 8 subgroups. They all had a
karyotype of 4 pairs of V-shaped chromosomes. Lemeunier et al.[15] called D. malerkotliana “the last
stage” of karyotypic evolution.
Hsu[16] thought that suzukii and obscure subgroups were nearest in genetic relationships by analyzing the male genitalia of the members in the D.
melanogaster species group. Then suzukii subgroup
was differentiated into two independent branches:
ananassae-montium, melanogaster-takahashii. Okada[17]
believed that the ancestor of D. melanogaster species
melanogaster, elegans, ficusphila-(suzukii-takahashii).
Yang et al.[23] sequenced the spacer region of histone
gene H2A-H2B and proposed that montium first
branched off, fol- lowed by ananassae and seven
Oriental subgroups could be divided into two branches:
suzukii-takahashii and eugracilis-melanogaster- rhopaloa-(elegans-ficusphila). Mou et al.[24] utilized a
molecular
approach
and
revealed
that
the
melanogaster species group clustered into three main
lineages: montium subgroup, ananassae subgroup,
Oriental subgroups (melanogaster, ficusphila, eugracilis, elegans, suzukii, and takahashii).
group was differentiated into three branches: suzukii,
The chromosome karyotypes of 34 species in the
melanogaster-takahashii-ficusphila-eugracilis and
D. melanogaster species group were analyzed and the
ananassae-montium. D. suzukii was the ancestral spe-
results are summarized in Tables 2 and 4. The detailed
cies. Bock and Wheeler[14] thought that ananassae
karyotype analysis here allows for the classification
.
of the melanogaster species group into five pedigrees:
combined morphology and chro-
1) elegans; 2) eugracilis-melanogaster-ficusphila; 3)
mosomal karyotypes of the D. melanogaster species
takkahashii-suzukii; 4) montium; and 5) ananassae.
group and concluded that the species group was dif-
The elegans subgroup differentiated first and the
ferentiated into three large clades: ananassae, mon-
ananassae subgroup differentiated last.
and montium subgroups branched off first
Ashburner et al.
[18]
[14]
tium and elegans-eugracilis-ficusphila-melanogastersuzukii-takahashii. Pelandakis and Solignac
www.jgenetgenomics.org
[19]
di-
The results basically supported the view by
Yang[23]. The differences between the results and
212
Table 4
Journal of Genetics and Genomics
遗传学报
Vol.34 No.3 2007
Karyotype classification of the eight subgroups
Subgroup
elegans
eugracilis
melanogaster
ficusphila
takahashii
suzukii
Karyotype
A
C
C
C
C, D
C, D
Yang’s were the ascription of the elegans subgroup
and the differentiation ordering of the eight subgroups.
The elegans subgroup was considered as an independent branch and was viewed as the ancestral subgroup. The montium subgroup branched off followed
by the ananassae subgroup, which was consistent
with the opinion of Yang. In this research, the two
subgroups branched off in the end during evolution,
while Yang assumed that the two subgroups branched
off first. The suzukii and takahashii subgroup were
sister subgroups and they branched off before montium and ananassae subgroups, whereas Yang thought
the sister subgroups branched off after montium and
ananassae subgroups. Despite these minor differences,
to a certain degree, the results that Yang [23] had got
by DNA sequencing were verified from the perspective of karyotypic evolution.
montium
B, C, C’, D,
D’, E
ananassae
F, G, H
Dros Inf Serv, 1980, 55: 25-26.
8
Ramachandra NB. Supernumerary chromosome in Drosophila
nasuta albomicana. Experientia, 1985, 41: 680-681.
9
Ramachandra NB, Ranganath HA. Characterization of heterochromatin in the B chromosomes of Drosophila nasuta
albomicana. Chromosoma, 1987, 95: 223-226.
10 Hatsumi M. Karyotype polymorphism in Drosophila albomicans. Genome, 1987, 29: 395-400.
11 Ling FY, Kitagawa O. The study of B B chromosomes in
Drosophila albomicans 1. The number and frequency of Bs in
Kunming population. Zoological Research, 1991, 1(12):
93-99 (in Chinese with an English abstract).
12 Qian YH, Zhang J, Xue XQ, Yi MS, Ma XJ. The study of B
chromosomes in Drosophila albomicans in Wuhan population.
Hereditas (Beijing), 1995, 17 (4): 19-20 (in Chinese with an
English abstract).
13 Clayton IR, Wheeler MR. A catalog of Drosophila metaphase
chromosome configurations. In: King R C, ed. Handbook of
Genetics. New York: Plenum, 1975, 471-512.
14 Bock IR, Wheeler MR. The Drosophila melanogaster species
group. Univ Tex Publ, 1972, 7213: 1-102.
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16 Hsu TC. The external genital apparatus of male Drosophilidae
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17 Okada T. Comparative morphology of Drosophilid flies. I.
Phallic organs of the melanogaster group. Kontyu, 1954, 22:
36-46.
18 Ashburner M, Bodmer M, Lemeunier F. On the evolutionary
relationships of Drosophila melanogaster. Dev Genet, 1984, 4:
295-312.
19 Pelandakis M, Solignac M. Molecular phylogeny of Drosophila based on ribosomal RNA sequences. J Mol Evol, 1993,
37: 525-543.
20 Inomata N, Tachida H, Yamazaki T. Molecular evolution of
the Amy multigenes in the subgenus of male Drosophila. Mol
Biol Evol, 1997, 14: 942-950.
21 Clark JB, Kim YC, Kidwell MG. Molecular evolution of P
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黑腹果蝇种组的核型与进化研究
邓秋红1,2，曾庆韬1，钱远槐1，李春选1，杨 勇1
1.湖北大学生命科学学院，武汉 430062；
2.华中科技大学生命科学与技术学院，武汉 430074
摘 要：观察了国内黑腹果蝇种组 34 种果蝇的有丝分裂中期核型，其中首次描述了一些新核型。系统地分析了黑腹果蝇种
组 8 个种亚组之间的核型进化关系及种间亲缘关系。结果是：elegans 种亚组的核型为 A 型；eugracilis、melanogaster 和
ficusphila 种亚组的核型为 C 型；takahashii 和 suzukii 种亚组的核型为 C 型和 D 型；montium 种亚组的核型为 B、C、C’、
D、D’、和 E 型；ananassae 种亚组的核型为 F、G 和 H 型。从核型分化的角度可以将黑腹果蝇种组分为 5 个谱系：elegans，
eugracilis-melanogaster-ficusphila，takkahashii-suzukii，montium，ananassae。这与 2004 年 Yang 等的观点基本一致，正好
从核型进化的角度验证了 Yang 通过 DNA 序列分析所得到的结果。差别只在于 elegans 种亚组，作者把它单独列为一支，
认为是祖先种亚组。通过选取同一种果蝇的几个不同地域单雌系的核型分析，结果表明：同一种果蝇的核型存在地域差异。
这种差异可能是由于不同生境造成，也可能是本身进化程度的差异，或是两种因素相互作用的结果。
关键词：果蝇属；黑腹果蝇种组；核型；亲缘关系；进化
作者简介：邓秋红（1978-）女，湖北赤壁人，华中科技大学生命科学与技术学院博士研究生，研究方向：生物化学与分子
生物学。E-mail: [email protected], [email protected]
www.jgenetgenomics.org