Хромосомный набор эндемичной для Байкала пиявки

UDC 595.143:591.813(282.256.341)


A. Natyaganova, I. Kaygorodova

Limnological Institute of Siberian Branch of Russian Academy of Sciences,
Irkutsk, Russia, avn@lin.irk.ru; irina@lin.irk.ru


A. Натяганова, И. Кайгородова

Лимнологический институт СО РАН, Иркутск, Россия

Baikal is the oldest (25–30 MY), the deepest (1637 m), the largest (23,000 km3) repository of fresh water of the planet (20 % drinking water) (Lake Baikal: Evolution and Biodiversity, 1998). The lake has a unique complex of living organisms (1550 animal species and over 1000 species of plants), which are adapted to a variety of environmental conditions, having mastered and repopulating the diversity of habitats from interstitial zone to maximal depths (Lake Baikal and its Catchment area, 2002). Despite a 200-year history of limnological studies, Baikal is still full of «white spots», one of them is the fauna of parasitic annelids. Baikal leeches demonstrate a high level of biological diversity (11 genera) and endemism, both at the genus level and at the species level. These species are adapted to living in cold, clean, oxygenated water and fed by the Baikal endemic animals: bullheads, amphipods, and perhaps other groups. If the modern approaches have been successfully applied to clarify the phylogeny of both European and North American leeches, the evolutionary history and phylogeny of the unique Baikal fauna remains to be examined.

Сhromosomes set analyses are regarded as a source of useful information for solving taxonomic problems of leeches (Cichocka, Bielecki, 2008). Moreover, a careful karyological study of this group using methods of differential staining and molecular cytogenetic analysis is very promising for understanding the process of speciation (Vitturi et al., 2002). To date, the numbers of chromosomes were specified for 22 species from about 500 world known species of the Hirudinea.

In this study we investigated the chromosome set of the Baikal endemic species of leeches Baicalobdella torquata (Grube, 1871), parasitic on Eulimnogammarus verrucosus (Gerstfeldt, 1858) (Crustacea, Amphipoda). Amphipods were collected in May 2011 on sandy-rocky ground in the coastal zone of Southern Baikal from depth 0.3–0.5 m. Incidence of leech infection on collected amphipods was up to 30 %, with intensity – from 1 to 5 specimens of parasites per individual. Air-dried cytological preparations of these leeches were made from the sperm sacs after colchicine pretreatment. Microscopic analysis showed that there are 30 double-armed chromosomes in mitotic metaphase plates. These chromosomes are rather small; their lengths are 1–3 µm. 15 bivalents (2–7 µm) clearly revealed at the stage of diakinesis-metaphase-I. Comparison with the currently available data (Cichocka, Bielecki, 2008; Utevsky et al., 2009) leads to the conclusion that the Baikal endemic leech species B. torquata has a unique set of chromosome (n = 15, 2n = 30) and karyologically differ of all known taxa.

Acknowledgements. This research was supported by RFBR grants # 11-04-90452, # 11-04-01394.

Zoocenosis — 2011
Біорізноманіття та роль тварин в екосистемах: Матеріали VІ Міжнародної наукової конфе­ренції. – Дніпропетровськ: Вид-во ДНУ, 2011. – С. 109.