Research Article |
Corresponding author: Mukhamed Karmokov ( lacedemon@rambler.ru ) Academic editor: Veronika Golygina
© 2016 Mukhamed Karmokov, Azamat Y. Akkizov.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Karmokov MKh, Akkizov AY (2016) Karyotype characteristics, larval morphology and chromosomal polymorphism peculiarities of Glyptotendipes salinus Michailova, 1983 (Diptera, Chironomidae) from Tambukan Lake, Central Caucasus. Comparative Cytogenetics 10(4): 571-585. https://doi.org/10.3897/CompCytogen.v10i4.9400
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Data on the karyotype characteristics, larval morphology and features of chromosomal polymorphism of a population of Glyptotendipes salinus Michailova, 1983 (Diptera, Chironomidae) from Tambukan Lake (on the northern macroslope of the central Caucasus) are presented. It was found that diagnostic larval characters of G. salinus from Caucasus in general are similar to those described in previous studies, but with some significant differences. By some morphological characteristics Caucasian larvae appeared to be closer to G. barbipes than to ones provided for European larvae of G. salinus by
Diptera , Chironomidae , Glyptotendipes salinus , larval morphology, polytene chromosomes, chromosomal polymorphism, genetic distances, Tambukan Lake, central Caucasus (northern macroslope)
Glyptotendipes salinus was first described by Michailova (1987) from Bulgaria. According to Fauna Europaea web source (http://www.faunaeur.org) the species is known in Europe from Austria, the British Isles and Bulgaria.
The karyotype of G. salinus has been studied from Bulgaria (Michailova 1987), Russia and Kazakhstan (
The species is a sibling species of G. barbipes that allows study of the earlier phases of divergence of the species in genus Glyptotendipes (
Earlier it was shown that G. salinus occurs in brackish water, while sibling species G. barbipes prefers fresh water (
The aim of the work was to present the description of karyotype characteristics, larval morphology peculiarities and chromosomal polymorphism of G. salinus from Tambukan Lake (northern macroslope of the central Caucasus). Also it was very important to compare chromosomal polymorphism characteristics of G. salinus from the Caucasus with earlier studies.
The fourth instar larvae of Glyptotendipes were used in the karyological study. The larvae were collected from one site of the central Caucasus: 17.05.13, 43°27.30'N; 43°09.75'E, southern shore of Tambukan Lake, altitude ca. 550 m a.s.l. Tambukan Lake is a lake with bitter salt water (salinity varies from 30 to 100 grams per liter) located in the northern macroslope of the central Caucasus, near the border of Stavropol Krai and the Republic of Kabardino-Balkaria of Russia. The lake’s surface area is 1.87 km2, and its depth ranges between 1.5–3.1 m. With regard to vertical zonation, the collection site belongs to the steppe zone (typification of the zone variants was given according to
The morphological terminology follows
Larvae for karyotype analysis were fixed in ethanol-glacial acetic acid (3:1). Slides of the chromosomes were prepared using the ethanol-orcein technique (see
Microscope Carl Zeiss Axio Imager.A2 was used to study the chromosome slides. The software package STATISTICA 10 was used for statistical analysis (cluster analysis).
The following parameters were used for comparison of characteristics of chromosomal polymorphism: the number of banding sequences in a population, the percentage of heterozygous larvae, and number of heterozygous inversions per specimen. Genetic distances between populations were calculated according to Nei criteria (
The larvae of Glyptotendipes in the studied site were attributed to G. salinus by both morphological and chromosomal characteristics. Morphological characteristics of larva are presented in Fig.
The larva of G. salinus from Tambukan Lake. a gular sclerite b mentum c antenna d premandible e mandible f ventromental plate g ventral tubuli on segment VIII.
The diagnostic larval characters of G. salinus from the Caucasian site in general are similar to those described previously for this species by Michailova (1987),
The diploid number of chromosomes in G. salinus karyotype is 2n = 8, chromosome arm combination is AB, CD, EF, and G (Fig.
Karyotype of G. salinus from the Tambukan Lake; salA1.1, salD1.1 etc. – zygotic combinations of banding sequences; BR – Balbiani rings, N – nucleoli. Arrows indicate centromeric regions.
The centromeric bands of long polytene chromosomes of G. salinus from the studied populations are large and belong to v-type according to the classification by
Until now, eleven banding sequences have been described in the banding sequences pool of G. salinus (Table
Catalog of banding sequences in the banding sequences pool of G. salinus.
Arm | Sequence | Order of bands | Authors of mapping |
---|---|---|---|
A | salA1 | 1a-b 5n-t 6a-n 2d-h 3ba 2u-i 3c-t 4a-v 5a-m 2cba 1t-n 1c-m 6o-t 7a-s |
Andreeva et al.1983 |
salA2 | 1ab 5n-t 6a-d 5h-a 4v-a 3t-c 2i-u 3ab 2h-d 6h-e 5i-m 2c-a 1t-n 1c-m 6o-t 7a-s | Original data | |
B | salB1 | 13z-a 12t-a 11o-a 10v-a 9n-a 8p-a 7c-a | Andreeva et al.1983 |
salB2 | 13-z-j 9d-h 10a-v 11a-o 12a-t 13a-i 9cba 8p-a 7s-a | Original data | |
C | salC1 | 1a-o 4v-k 1p-r 2a-n 3a-p 4a-m 5a-z 6a-n 7a-i | Andreeva et al.1983 |
salC2 | 1a-o 5f-a 4m-a 3p-a 2n-a 1r-p 4n-v 5l-z 6a-n 7a-i | Andreeva et al.1983 | |
salC3 | 1a-o 5f-a 4m-a 3p-a 2n-a 4u-n 1p-r 4v 5l-z 6a-n 7a-i |
Andreeva et al.1983 | |
salC4 | 1a-d 4e-m 5a-k 1o-e 4d-a 3p-a 2n-a 1r-p 4n-v 5l-z 6a-n 7a-i | Andreeva et al.1983 | |
D | salD1 | 12p-a 11m-a 10w-a 8a-g 8ih 8n-j 8o-q 9a-x 7i-a |
Andreeva et al.1983 |
E | salE1 | 1a-u 3a-q 4a-w 5a-t 6a-r 2l-a 1v 6s-w 7a-l | Andreeva et al.1983 |
salEX | Not mapped | ||
F | salF1 | 11w-a 10s-a 9t-a 8m-a 7l-a | Andreeva et al.1983 |
G | salG1 | 5t-a 4i-a 3q-a 2r-a 1g-a | Andreeva et al.1983 |
salG2 | 5t-a 4i 2b-r 3a-g 4a-h 2a 1g-a | Andreeva et al.1983 | |
salG3 | 5t-j 2h-r 3a-g 4a-i 5a-i 2g-a 1g-a | Original data |
Banding sequence | Populations | |||||
---|---|---|---|---|---|---|
Kazakhstan | Altai Krai | Central Caucasus, Tambukan Lake (original data) 63 larvae | ||||
STS, Atomnoe Lake ( |
STS, Shagan Lake ( |
Altai, Bulatovo Lake ( |
Altai, Gorkoe Lake ( |
Altai, Bolshoe Utichie Lake ( |
||
salA1 | 1 | 1 | 1 | 1 | 1 | 0.992 |
salA2 | 0 | 0 | 0 | 0 | 0 | 0.008 |
salB1 | 1 | 1 | 1 | 1 | 1 | 0.317 |
salB2 | 0 | 0 | 0 | 0 | 0 | 0.683 |
salC1 | 0.220 | 0.164 | 0.630 | 0.622 | 0.530 | 0.016 |
salC2 | 0.780 | 0.817 | 0.370 | 0.378 | 0.470 | 0.984 |
salC3 | 0 | 0.009 | 0 | 0 | 0 | 0 |
salC4 | 0 | 0.009 | 0 | 0 | 0 | 0 |
salD1 | 1 | 1 | 1 | 1 | 1 | 1 |
salE1 | 1 | 1 | 1 | 1 | 1 | 0.992 |
salEX | 0 | 0 | 0 | 0 | 0 | 0.008 |
salF1 | 1 | 1 | 1 | 1 | 1 | 1 |
salG1 | 0.950 | 0.991 | 1 | 1 | 1 | 0.968 |
salG2 | 0.050 | 0.009 | 0 | 0 | 0 | 0 |
salG3 | 0 | 0 | 0 | 0 | 0 | 0.032 |
Number of banding sequences in population | 9 | 11 | 8 | 8 | 9 | 12 |
Percentage of heterozygous larvae | 40 | 29 | 48 | 57 | 62 | 51 |
Number of heterozygous inversions per specimen | 0.34 | 0.30 | 0.60 | 0.61 | 0.60 | 0.60 |
Arm A has two banding sequences, salA1 and salA2 (Figs
Banding sequences in arms A and B of G. salinus; a homozygotes salA1.1 b homozygotes salB2.2 c homozygotes salB1.1, Designations as in Fig.
Chromosome inversions in different arms of G. salinus from Tambukan Lake. Heterozygous zygotic combination key: a salA1.2 b salB1.2 c salC1.2 d salE1.X. Designations as in Fig.
It is new for the species and described for the first time here (Fig.
salA2 1ab 5n-t 6a-d 5h-a 4v-a 3t-c 2i-u 3ab 2h-d 6h-e 5i-m 2c-a 1t-n 1c-m 6o-t 7a-s
Arm B has two banding sequences, salB1 and salB2 (Figs
salB2 13-z-j 9d-h 10a-v 11a-o 12a-t 13a-i 9cba 8p-a 7s-a
The banding sequence salB2 was found with high frequency in both homozygous (salB1.1 – 0.095, salB2.2 – 0.445) and heterozygous states (salB1.2 – 0.460).
Arm C has two banding sequences, salC1 and salC2. The banding sequence salC2 was dominant in this population (Fig.
Banding sequences in the arms C and D of G. salinus. Key: a homozygotes salC2.2 b homozygotes salD1.1 Designations as in Fig.
Arm D is monomorphic with banding sequence salD1 (Fig.
Arm E had two banding sequences, salE1 and salEX (Table
Banding sequences in the arms E and F of G. salinus. – The homozygotes salE1.1 and salF1.1. Designations as in Fig.
Arms F is monomorphic with banding sequence salF1 (Fig.
Arm G had two banding sequences, salG1 and salG3. The banding sequence salG1 was dominant in the population (Fig.
salG3 5t-j 2h-r 3a-g 4a-i 5a-i 2g-a 1g-a
Data for Russian (Altai Krai) and Kazakhstan populations are presented on the basis of publication of
Arm A. The populations from Altai and Kazakhstan (
Arm B was monomorphic in populations of Altai and Kazakhstan and presented only by the banding sequence salB1 (Table
Arm C of G. salinus in all the studied populations was polymorphic. However in Altai populations the predominant banding sequence was salC1, whereas in Kazakhstan population dominated salC2. The population of the North Caucasus is closer to populations of Kazakhstan with salC2 dominating with even higher frequency (Table
Arm D of G. salinus was monomorphic in all the studied populations.
Arm E was monomorphic in populations of Altai and Kazakhstan and low polymorphic in Caucasian population with the same dominant banding sequence salE1. A new banding sequence salEX was found in the Caucasian population with very low frequency (0.008) and might be endemic for the region.
Arm F of G. salinus was monomorphic in all the studied populations and presented only by the sequence salF1.
Arm G of G. salinus was monomorphic in populations of Altai and low polymorphic in populations of Kazakhstan and the Caucasus, although in all populations the dominant banding sequence was salG1. At the same time Kazakhstan and Caucasian populations differ by the set of rare inversions: salG2 was found in Kazakhstan while salG3 occurred in Caucasian population.
The inversion polymorphism of populations of G. salinus from the North Caucasus has a high level of heterozygous inversions per specimen and is similar to those of the Altai populations (Table
Genetic distances (Table
Value of genetic distances between the different populations of G. salinus.
Population | STS, Atomnoe Lake | STS, Shagan Lake | Altai, Bulatovo Lake | Altai, Gorkoe Lake | Altai, Bolshoe Utichie Lake | Central Caucasus, Tambukan Lake |
---|---|---|---|---|---|---|
STS, Atomnoe Lake | 0 | |||||
STS, Shagan Lake | 0.00057 | 0 | ||||
Altai, Bulatovo Lake | 0.02639 | 0.03204 | 0 | |||
Altai, Gorkoe Lake | 0.02539 | 0.03091 | 0.00001 | 0 | ||
Altai, Bolshoe Utichie Lake | 0.01519 | 0.01943 | 0.00153 | 0.00129 | 0 | |
Central Caucasus, Tambukan Lake | 0.08167 | 0.07787 | 0.13945 | 0.13777 | 0.11999 | 0 |
In the northern Caucasus (central part of the northern macroslope) as well as in European Russia, G. salinus has been found for the first time.
As mentioned above, the diagnostic larval characters of G. salinus from the Caucasus in general are similar to those described by Michailova (1987),
On the basis of morphological data one can conclude that the Caucasian population of G. salinus can be a markedly diverged population of the species, probably even subspecies. This conclusion is also supported by comparative analysis of inversion polymorphism between the Caucasian population and populations of other regions.
At present, 15 banding sequences including four new ones – salA2, salB2, salEX, and salG3 – are known in the banding sequences pool of G. salinus.
By frequencies of the banding sequences Caucasian population are closer to the Kazakhstan populations than to populations from Altai, but it clearly differ from populations from both other regions by the presence of four new banding sequences. The inversion polymorphism in population of G. salinus from the North Caucasus has a high level of heterozygous inversions per specimen and is similar to those of the Altai populations (Table
The population of the central Caucasus on the dendrogram of genetic distances (Fig.
We are sincerely grateful to Dr NA Durnova (Saratov State Medical University named after V.I. Razumovsky) and Dr SV Zhirov (Zoological Institute RAS) for their help in the preparation of this paper. Financial support was provided by the program of the Presidium of the Russian Academy of Sciences “Live nature: modern state and problems of development”.