Holarctic Marmots as a factor of Biodiversity.
Rumiantsev V.Yu;, Nikol'skii A.A. & Brandler O.V. eds.,
Abstracts, 3d Conference on Marmots (Cheboksary, Russia, 25-30 August 1997),
Moscow ABF 1997, 216p.

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A STUDY ON POPULATION GENETIC STRUCTURE OF MONGOLIAN MARMOT AND SOME PROBLEMS OF PLAGUE

J. Batbold

Faculty of Biology, National University of Mongolia, Mongolia

In this paper a general picture of population genetic structure of Mongolian marmot (Marmota sibirica Radde, 1862), genetic distances between marmot populations are differed with respect to the prevalence of plague and plague epizootic influence on population structure were described.

We firstly studied blood protein polymorphism and population genetic structure of Mongolian marmot (Batbold, 1994; Batbold, Batsuuri, 1995 a,b). Blood samples of 1123 marmots from 3 separate populations were collected for analysis by polyacrylamid gel electrophoresis.

Four polymorphic loci from serum proteins of Mongolian marmots were observed. The blood serum protein - Haptoglobin (Hp) of the Mongolian marmot with 3 hereditary phenotypes determined by Hp^S and Hp^F alleles; the Transferrin (Tf with 6 phenotypes, by Tf^K, Tf^L and Tf^M alleles; the Post-albumin (Pa) 6 phenotypes, by Pa^A, Pa^B and Pa^C alleles and the Albumin (Al) 3 phenotypes, by Al^A and Al^B alleles were observed and confirmed. The mean frequencies of the observed alleles for Mongolian marmots are showen in the table.

The mean heterozygosity of marmot populations for 4 polymorphic loci was 25.56% within 24.0-27.1% range. The means of inbreeding in marmot population were F_IT=4.56%, F_IS=2.84% and FST=1.68%. The F-statistics or genetic differentiation was ranged from 0.009928-0.021314. We selected and studied 3 populations of Mongolian marmot which are geographically isolated and differed with respect to the prevalence of plague: high intensity plague focus, non-intensity and free from plague.

These populations were almost identical by frequencies of alleles in the Hp, Pa and Al loci (I = 0.9967 0.001), but were differed by frequencies of alleles in the tansferrin's locus (I=0.9361 0.05). The genetic distances (Nei's distance: D) of marmot populations geographically remote from each other were 0.0022-0.0192, and we found a correlation between genetic and geographic distances (r=0.977). The marmot population within high intensity of plague clearly differed from the 2 populations in areas of non-intensity and free of plague in their population genetic structure (D=0.0157-0.0192). The D coefficient was very low between the populations in non-intensity plague areas and populations free of plague (D=0.0022). The high rate of genetic differentiation (0.021314) and the observed heterozygosity lower than expected (Ho=25.5

Plague epizootic influence on marmot population structure was studied for 5 years in the Gobi-Altain Tonkhil sum's focus. Prior to initiation of the plague epizootic, the genetic stcucture of the marmot population within tbe plague focus was charactcrized by: low heterozygosity or more homozygosity than the expected (H_o=0.2583e=0.2883), population subdivided into many small groups, high inbreeding rates (F_SI=0.062320, F_IS=0.042750), and the population susceptible to natural selection. Following infection of the population by plague, Hp^S, Tf^M, Tf^K and Al^B allelic frequencies decreased and frequencies of the Tf^L, Al^A, Hp^F alleles increased. Among the polymorphic hereditary systems studied, intense selection during the epizootic acted most strongly on the transferrin locus (S=0.545). The Tf^L gene frequency increased 1.7 times, and both Tf^K and Tf^M gene frequencies decreased (selection rate of both alleles S_TfK=0.67; S_TfM=0.56) during the plague epizootic. After the epizootic, the FIS disappeared from the population (F_IS=-0.077585), the F_ST decreased 2 times (F_ST=0.030214), heterozygosity was increased by 15.8% (H_o=0.2992, H_e=0.2684), and population survival abilities (or average fitness in relation to
selection) improved.

Table.

Alleles	Gene frequencies		Heterozygosity
	ranges	mean, st. div.
HpS	0.87-0.92	0.9026±0.03	0.1901
HpF	0.08-0.13	0.0974±0.03
TfK	0.26-0.28	0.2717±0.01	0.5834
TfL	0.18-0.39	0.3097±0.11
TfM	0.35-0.54	0.4186±0.11
PaA	0.01-0.06	0.0275±0.03	0.1614
PaB	0.88-0.91	0.8912±0.02
PaC	0.03-0.12	0.0813±0.03
AlA	0.91-0.96	0.9360±0.03	0.0764
AlB	0.03-0.09	0.0640±0.03

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