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B chromosomes in the wood mice [genus Apodemus]

100%

Zima J., Macholan M.

Acta Theriologica. Supplement

1995

nr 03

Spatial and temporal distribution of supernumerary or B chromosomes were studied in natural populations of wood mice. A total of 859 individuals belonging to several species from Eurasia were examined. A very high percentage of individuals possessing B chromosomes was found in Apodemus peninsulae (97.9%, n = 47), a high percentage in A. flavicollis (42.5%, n = 362), and a low one in A. syluaticus (2.4%, n = 210). No B chromosomes were observed in A. uralensis (n = 10), A. fulvipectus {n = 19), A. hermonensis (n = 1), A. agrarius (n = 58), A. mystacinus (n = 7), and in Apodemus species collected in Turkey (n = 74), Israel (n = 1), Azerbaijan (n = 2), Tadjikistan (n = 24), and Kyrghyzstan (n = 44). A modest to high frequency of B chromosomes was thus observed particularly in the species confined to a forest environment, whereas no B's were found in the species dwelling in open, steppe-like or rocky habitats. Both in A. peninsulae and A. flavicollis the frequency of B chromosomes varied among local populations. Follow-up studies revealed stability in the respective proportions of B chromosomes during subsequent years. However, no unambiguous interrelationship could be found between the frequency of B chromosomes and various biological and/or ecological variables. Therefore it seems that the incidence of B chromosomes is mainly determined by stochastic effects operating within the specific genetic background of a population.

Conservation genetics of managed ungulate populations

67%

Scribner K. T.

Acta Theriologica. Supplement

1993

tom 38

nr 2

Natural populations of many species are increasingly impacted by human activities. Perturbations are particularly pronunced for large ungulates due in part to sport and commercial harvest, to reductions and fragmentation of native habitat, and as the result of reintroductions. These perturbations affect population size, sex and age composition, and population breeding structure, and as a consequence affect the levels and partitioning of genetic variation. Three case histories highlighting long-term ecological genetic research on mule deer Odocoileus hemionus (Rafinesque, 1817), white-tailed deer O. virginianus (Zimmermann, 1780), and Alpine ibex Capra i. ibex Linnaeus, 1758 are presented. Joint examinations of population ecological and genetic data from several populations of each species reveal: (1) that populations are not in genetic equilibrium, but that allele frequencies and heterozygosity change dramatically over time and among cohorts produced in successive years, (2) populations are genetically structured over short and large geographic distances reflecting local breeding structure and patterns of gene flow, respectively; however, this structure is quite dynamic over time, due in part to population exploitation, and (3) restocking programs are often undertaken with small numbers of founding individuals resulting in dramatic declines in levels of genetic variability and increasing levels of genetic differentiation among populations due to genetic drift. Genetic characteristics have and will continue to provide valuable indirect sources of information relating enviromental and human perturbations to changes in population processes.

Ograniczanie wyników

2 Acta Theriologica. Supplement

1 Macholan M.

1 Scribner K. T.

1 Zima J.

1 1995

1 1993

Wyniki wyszukiwania

B chromosomes in the wood mice [genus Apodemus]

Conservation genetics of managed ungulate populations