NEW DATA ABOUT HYBRIDIZATION OF SPECKLED (SPERMOPHILUS SUSLICUS GÜLD.), AND RUSSET (SPERMOPHILUS MAJOR PALL.) GROUND SQUIRRELS IN A WIDE ZONE OF SYMPATRY

Abstract

Background. Studies of hybrid zones and animal populations of hybrids in space and time is an actual problem of evolution biology and zoology. Using of molecular markers and bioacoustics in study of hybrid zones and populations helps to reveal not only hybrid origin of individual but also its destiny in population. Goals of work were to study modern distribution and sympatry zone’s state of Speckled and Russet Ground squirrels in Volga Region and to reveal interspecific hybrids in contact colonies basing on complex of molecular markers and parameters of acoustic signals. Materials and methods. On the territory of Ulyanovsk region 72 colonies were surveyed, including 35 colonies of Russet Ground Squirrel, 27 colonies of Speckled Ground Squirrel, 6 combined colonies with specific separation on microstations, 3 mixed colonies without separation and 1 former hybrid colony in Chuvashiya. In a contact colonies (n = 9) 217 samples were collected. Molecular genetic analysis was conducted on 5 markers (D-loop, Hoxb5, р53, ZfX, SmcY) for determination of individuals’ origin. Bioacoustics analysis was based on records of warning signals, processed in *WAV-format with 48 kHz discretization frequency and 16-bit depth. Frequency and interval parameters were obtain with Avisoft-Sonograph software. 148 signals of adult Russet (n = 11, 71 signals) and Speckled Ground squirrels (n = 11, 61 signals) and possible interspecific hybrids (n = 3, 19 signals) were processed. Statistical analysis of obtained data were perform in STATISTICA 10.0. Results. Modern state of Russet and Speckled Ground squirrels’ zone of sympatry quantitatively and structurally differs from previous. Among 72 observed colonies 62 (86 %) are monospecific (S. major – 35, 48,5 %; S. suslicus – 27, 37,5 %) and only 10 are contact (14 %). Genetic structure analysis of 10 modern contact colonies showed that in 6 combined colonies only individuals of contact species were revealed. Unlike of those in 3 mixed colonies hybrids were registered. Stepwise discriminant analysis of acoustic signals’ parameters united in three groups (Russet (n = 11, 69 signals) and Speckled (n = 11, 56 signals) Ground squirrels and their hybrids (n = 3, 18 signals)) revealed intermediate type of inheritance of parental acoustic signs by hybrids. Conclusions. Definite relation between composition and individuals’ number of contact colonies and facts of hybrids foundation in them was revealed. When individuals’ number is depressed or even one of parental species totally absent share of hybrids can reach 75 %. When number of both species is high and there is no separation on microstations hybrids in such colonies were found very rare and probably were result of sporadic hybridization.

Keywords

• speckled ground squirrel
• russet ground squirrel
• interspecific hybridization
• zone of sympathy
• molecular genetic analysis
• bioacoustic analysis
• hybrids