Cytogenetical Characteristic of Insectivora Species in Strandzha Mountain (Southeastern Bulgaria)

Оригинален научен труд Original Scientiﬁ c Article

CYTOGENETICAL CHARACTERISTIC OF INSECTIVORA SPECIES IN STRANDZHA MOUNTAIN (SOUTHEASTERN BULGARIA)

Nasko I. ATANASOV & Tsenka G. CHASSOVNIKAROVA

Institute of Zoology, Bulgarian Academy of Sciences, 1 Tzar Osvoboditel blvd., Soﬁ a 1000, Bulgaria

ABSTRACT

Atanasov I. N. & Chassovnikarova G. T. (2008): Cytogenetical characteristic of Insectivora species in Strandzha Mountain (Southeastern Bulgaria). Proceedings of the III Congress of Ecologists of the Republic of Macedonia with International Participation, 06-09.10.2007, Struga. Special issues of Macedonian Ecological So- ciety, Vol. 8, Skopje. The Insectivora species lesser white-toothed shrew (Crocidura suaveolens Pallas, 1811) and Southern water shrew (Neomys anomalus Cabrera, 1907), inhabiting Strandzha Mountain, were cytogenetically characterized. For the fi rst time, the male karyotype of lesser white-toothed shrew from Bulgaria were studied (2n=40, NFa=46, NF=50) and morphology and size of the Y-chromosome were determined. The Х-chromosome is a large submetacentric and the У-chromosome is acrocentric. The karyotype analysis of the Crocidura suaveolens confi rms its karyotype’s relative stability. The karyotype of Neomys anomalus in Bulgaria (2n=52; NF = 98; NFa = 94) is described for the fi rst time. The X chromosome is subtelocentric and the Y chromosome is submetacentric.

Key words: Insectivora, Crocidura suaveolens, Neomys anomalus, karyotype, Bulgaria

Introduction olens was described as 2n=40 (Meylan & Hausser 1974). The chromosome polymorphism is rare for Strandzha Mountain (Southeastern Bulgaria) the populations of white-toothed shrews and it is a has specifi c geological, climatical, and biogeograph- result mainly of pericentric inverions and different ical characteristics. It belongs to the European de- patterns of heterochromatin distribution (Zima et al. ciduous forest region, in the Euxinian province. It 1998). In C. suaveolens, additional В-chromosomes is characterised with an ancient, mostly, mesofi lous (Meylan & Hausser 1974) and changes in the size and, partly, hygrophilic deciduous forest vegetation and location of the centromere in the Х-chromosome with Euxinian fl oristic elements. This leads to the (Ivanitskaia 1989) were found. The Х-chromosome formation of characteristic ecosystems with a large is usually biarmed - submetacentric and includes biological diversity, in which, up till now, a consid- 6-8% of the haploid genome (Madalena & Rue- ereable amount of natural and seminatural habitats di 1994), while the Y-chromosome is acrocentric have been established. The pesence of thirthy one (Meylan 1966; Rimsa et al. 1978; Catzefl is et al. species of small mammals in Strandzha Mountain is 1985; Vogel еt al. 1986; Graphadatsky et al. 1988, established and this characterized the region as the 1993; Zima et al. 1998). most representative for the small mammal’s biodi- Based on karyological studies and isoenzyme versity in Bulgaria. analyses, only two species have been determined in The aim of the present investigation is to car- Bulgaria – bicolored white-toothed shrew (C. leu- ry out the cytogenetical characteristic of Insectivora codon) and lesser white-toothed shrew (C. suaveo- species Crocidura suaveolens and Neomys anoma- lens) (Poitevin 1984; Belcheva & Kolevska 1992). lus in Strandzha Mountain. These species are includ- The karyotype of C. suaveolens (1 female from Do- ed in Bern Convention on Concervation of European brich) was identifi ed as 2n=40, NF=50. Wildlife and Natural Habitats, appendix three, which The genus Nеomys is remarcable by the fact, involves protected species with regulated use. that the species inhabiting Europe N. аnomalus (Ca- The genus Crocidura shows a high degree brera 1907) and N. fodiens (Pennant 1771) have a of karyotype evolution. The karyotype of C. suave- simmilar karyotype (2n = 52, NF=90-98). The auto-

17 Nasko I. ATANASOV & Tsenka G. CHASSOVNIKAROVA

Fig.1. Metaphase plate and karyotype of male lesser white-toothed shrew (C. suaveolens) from Strandzha Mountain. somes are twenthy two biarmed pairs and three ac- scribed. Intraindividual polymorphism of the mor- rocentric pairs. Sex chromosomes polymorphism in phology and the size of the sex chromosomes is es- the genus is described. The X chromosome is subte- tablished (Belcheva & Kolevska 1992). locentric, submetacentric or metacentric, while the Y chromosome is subtelocentric, submetacentric or Material and Methods acrocentric (Maylan 1964; Fredga & Levan 1969; Rimsa et al. 1978; Zima 1983, 1984; Jimenez et al. Three males of the lesser white-toothed shrew 1984; Ivanitskaia 1989; Belcheva & Kolevska 1992; (C. suaveolens) and three males and two females of Graphadatsky et al. 1993). the Southern water shrew (N. anomalus) from the The karyotype investigations of N. anoma- Strandzha Mountain were studied. lus in Europe are insufi tient. The diploid chromo- Because of the diffi culty in the external mor- some number is identically with those of N. fodi- phologic determination between the two Neomys ens (2n=52), NF varies from 94 to 98 (Maylan 1966; species, the N. anomalus species diagnostic is car- Rimsa et al. 1978; Zima et al. 1998). Only in the ried out according to morphometric and craniomet- Spanish populations the sex chromosomes are de- ric criteria (Peshev et al. 2004). All investigated in- scribed as subtelocentrics (Jimenez et al. 1984). dividuals have a tail length less than 55 mm, tail In Bulgaria the genus Neomis includes the without keel or poorly developed keel, confi ned to sympathric species Northern water shrew (N. fodi- the terminal third of the tail. The hind foot length ens) and Southern water shrew (N. аnomalus). On- is less than 18,4 mm. The craniometrical criteria in- ly the karyotype of the Northern water shrew is de- clude the height of coronoid process usually under

18 Зборник на трудови од III Конгрес на еколозите од Македонија Cytogenetical characteristic of Insectivora species in Strandzha Mountain (Southeastern Bulgaria)

Fig. 2. Metaphase plate and karyotype of male sauthern water shrew (Neomys anomalus) from Strandzha Mountain.

4,8 mm and the length of mandible with lower inci- between ﬁ rst and second autosome pairs, while the sor usually under 14,2 mm. У-chromosome was acrocentric, as large as the lon- The karyotype in bone marrow cells was ana- ger arm of the Х-chromosome (Fig. 1). lyzed by the standard method using hypotonization in 0.56 % solution of KCl for 30 min, ﬁ xing of the chro- Sauthern water shrew (Neomys anomalus) mosomes in methanol and acetic acid (3:1), and prep- All investigated individuals have a diploid aration of air-dried slides. A total of 148 metaphases chromosome number 2n= 52, NF = 98, NFa = 94. were analyzed, with the chromosomes in the karyo- This karyotype is identical with the species karyotype organized by morphology and decreasing size. type described in Europe (Maylan, 1966; Rimsa et al., 1978; Jimenez et al., 1984; Zima et al., 1998). Results The autosomes are biarmed: 10 metacentric, 10 submetacentric, 2 subtelocentric and 3 acrocentric pairs Lesser white-toothed shrew (C. suaveolens) (Fig.2 and Fig. 3). The diploid chromosome number of all the No sex chromosome polymorphism is es- specimens studied was 2n=40, NFa=46, NF=50. The tablished. The subtelocentric X chromosome is be- autosomes were 15 pairs acrocentric chromosomes tween the 4th and the 5th autosome pairs by its size. and 4 pairs were biarmed chromosomes, of which, 1 The Y chromosome is submetacentric as long as the pair metacentric chromosomes, 1 pair submetacen- longe arm of the X chromosome (Fig.2). It differs tric and 2 pairs subtelocentric chromosomes. The from the subtelocentric Y chromosome, described in Х-chromosome was large submetacentric, in size Spanish populations (Jimenez et al., 1984).

Proceedings of the III Congress of Ecologists of Macedonia 19 Nasko I. ATANASOV & Tsenka G. CHASSOVNIKAROVA

Fig. 3. Metaphase plate and karyotype of female sauthern water shrew (Neomys anomalus) from Strandzha Mountain.

Discussion tive stability of the karyotype. For the fi rst time the karyotype of the South- For the fi rst time, male specimens of less- ern water shrew in Bulgaria was described. The car- er white-toothed shrew from Bulgaria were stud- ried out karyotype analysis of Strandzha Mountain ied and morphology and size of the Y-chromosome population demonstrates that there are differences were determined. The morphology of autosomes and between the considered as identical karyotypes of sex chromosomes do not differ from this described the water shrews in Bulgaria. According to Belche- of the only female specimen from Dobrich (Belche- va & Kolevska (1992) the karyotype of the Northern va, Kolevska, 1992) and of the specimens from the water shrew has 10 metacentric, 10 submetacentric, populations in France (Maylan 1966), Switzerland 2 subtelocentric and 3 acrocentric autosome pairs. (Meylan & Hausser 1974), Tajikistan (Ivanitskaia et Intraindividual sex chromosome polymorphism in al. 1977; Slovakia (Slivka 1977), Yugoslavia (Rimsa morphology and size of Y chromosome is described. et al. 1978), Czech Republic (Zima, Kral 1984), It- The X chromosome is a large submetacentric, but aly, Hungary, Greece, Cyprus, Israel (Catzefl is et al. in some metaphases the Y chromosome is small ac- 1985). This confi rms the conservatism of the kary- rocentric, shorter than the longe arm of the X chro- otype of C. suaveolens in the Palearctics and the mosome. In other metaphases the Y chromosome is hypothesis about its earlier formation from the hy- submetacentric or metacentric, longer than the longe pothetic ancestor karyotype. The karyotype evolu- arm of the X and in the last metaphases is a very tion of the species is demonstrated in the increased long submetacentric, longer than the longe arm of number of chromosomes and the chromosome arms. the X. Such polymorphism in morphology of the Y The karyotype analysis of the Crocidura suaveolens chromosome do not exists in the investigated popu- from the region of Strandzha has illustrated the rela- lations of N. anomalus in Strandzha Mountain. The

20 Зборник на трудови од III Конгрес на еколозите од Македонија Cytogenetical characteristic of Insectivora species in Strandzha Mountain (Southeastern Bulgaria)

X chromosome in N. fodiens is a large submetacen- Ivanitskaya, E.Yu., Isakov, S.I.& Korobitzyna K.V. tric, while the X in N. anomalus is middle-sized sub- (1977). Chromosome sets of two species of telocentric. This established difference in the kary- shrews from Tadjikistan, Sorex bucharensis otype of N. anomalus cytogenetically defi nes the Ognev, 1921 and Crocidura suaveolens Pal- Strandzha Mountain population. las, 1811 (Soricidae, Insectivora). Zool. zhur- nal 56 (12): 1896 - 1900. (in Russian) Acknowledgements: Ivanitskaya, E. (1989). Constitutitive heterochromatin and nucleolar organizer regions in karyo- The present study was supported by types of some shrews (Soricidae, Insectivo- MES-NSF - project No BУ-5-2005. ra). Genetika, 25: 1188 - 1198. (in Russian). Jimenez, R., Burgos, M. & Diaz de la Guardia, R. References (1984). Meiotic behavior of sex chromosomes and polymeiosis in three species of in- Belcheva, R., & Kolevska, N. (1992). Cytogenetical sectivores. Genetica 65: 187 - 192. study on some Soricidae (Insectivora, Mam- Maddalena, T.& Ruedi, M. (1994). Chromosom- malia). Ann. Univ. Sofi a 80:144-156. al evolution in the genus Crocidura (Insec- Bovey, R. (1949). Les chromosomes des Chiropteres tivora: Soricidae). In: Merritt, J.F., Kirkland, et des Insectivores. Rev. Suis. Zool. 56 (30): G.L.Jr. & Rose, R.K. (eds): Advances in the 371- 460. biology of Shrews. Carnegie Museum Nat. Catalan, J. (1984). Application de methodes gen- Hist. Special Publication, 18: 335 - 344. tiques d’ la systematique des musaraignes Meylan, A. (1964). Le polymorphisme chromo- (Soricides) de l“Europe meridionale. Mem. somique de Sorex araneus L. (Mamm. - In- Trav. E.H.P.E., Inst. Montpellier 15: 1- 85. sectivora). Rev. suisse Zool. 71 (43): 903 - Catzefl is, F. (1983). Relations genetiques entre trois 983. especes du genre Crocidura (Soricidae, Mam- Meylan, A. (1966). Donnees nouvelles sur les malia) en Europe. Mammalia, 47: 229 - 236. chromosomes des insectivores europeens Catzefl is, F., Maddalena, T., Hellwing, S. & Vogel, (Mamm.).- Rev. suisse Zool. 73 (3): 548 - P. (1985). Unexpected fi ndings on the taxo- 558. nomic status of East Mediterranean Croci- Meylan, A.& Hausser, J. (1974). Position cytotax- dura russla auct (Mammalia, Insectivora). onomique de quelques musaraignes du genre Zeitsch. Saugetierk. 50: 185 - 201. Crocidura au Tessin (Mammalia, Insectivo- Dulic, B. (1978). Chromosomes of small mammals ra). Rev. suisse Zool. 81: 701 - 710. from the Southwestern karstic regions of Yu- Poitevin, F. (1984). Biogeographie et ecolo- goslavia. In: II Intern. Theriol. Congr. Abstr. gie des Crocidures mediterraneennes (In- Brno: 33. sectivores, Soricides). Crocidura Peshev, T., Peshev, D.& Popov, V. (2004). Fauna russula (Hermann, 1780), Crocidura suaveo- Bulgarica Editio Academica “Marin Drinov”, lens (Pallas, 1811). Mem. Trav. E.P.H.E., 27: 632p. (in Bulgarian) Inst. Montpellier 14:1- 9. Fredga, K. & Levan, A. (1969). The chromosomes Rimsa, D., Zivkovic, S. & Petrov, B. (1978). The re- of the European water shrew (Neomys fodi- sults of cytogenetical study of shrews (Sori- ens). Hereditas 62: 348 - 356. cidae, Insectivora, Mammalia) in Yugoslavia. Graphodatsky, A. S., Radjabli, S.I., Zaitsev, M.V. & Biosystematika 4 (1): 209 - 215. Sharshov, A.V. (1993). The levels of chro- Zima, J. (1983). Chromosomes of the harvest mouse, mosome conservatism in the different groups Mycromys minutus from the Danube Delta of insectivores (Mammalia, Insectivora). In: (Muridae, Rodentia). Folia Zool. 31 (1): 19 Zaitsev M.V. (ed.): Questions of systematics, - 22. faunistics and paleontology of small mam- Zima, J. (1984). Chromosomes of certain small mals, Trudy zool. Inst. 243: 47 - 57. (in Rus- mammals from Southern Bohemia and the sian) Sumava Mts. (CSSR). Folia Zool. 33 (2): Graphodatsky, A.S., Radjabli, S.I., Sharshov, A.V. 133 - 141. & Zaitsev, M.V. (1988). Karyotypes of fi ve Zima, J. & Kral, B. (1984). Karyotypes of European Crocidura species of the USSR fauna. Cito- mammals I. Acta Sc. Nat. 18 (7): 1 - 51. logia, 30: 1247 - 1252. (in Russian). Zima, J., Lucacova, L. & Macholan, M. (1998). Harada, M., Yosida, T.H., Hattori, S. & Takada, S. Chromosomal evolution of shrews. In: (1985). Cytogenetical studies on Insectivora. Wojcik, J.M. & Wolsan, M. (ed.) Evolution III. Karyotype comparison of two Crocidu- of shrews, Mamm. Res. Inst., Polish Acad. ra species in Japon. Proc. Jap. Acad. 61: 371 Sci. :175 - 218. - 374.

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