Chromosome polymorphism in Bulgarian populations of the striped field mouse (Apodemus agrarius Pallas 1771)

Abstract

Abstract. Chromosome polymorphism in Bulgarian populations of the striped fi eld mouse (Apodemus agrarius Pallas, 1771) has been described. The diploid chromosome number is 2n=48 (NFa = 54). In the karyotype of 3 specimens from the Iskar region, the presence of an additional B chromosome has been established for the fi rst time. The autosomes are 19 acrocentric pairs, continuously decreasing in size, and 4 pairs of be-armed chromosomes, barely distinguishable by size and location of the centromere. Specimens with 3 pairs of metacentric chromosomes were fi rstly described in Bulgaria for the regions of Iskar and Omurtag. The localization of heterochromatin in the centromeric regions of the chromosomes, blocks of heterochromatin of different sizes, as well as intercalated bands, distinguishable in weakly spiraled chromosomes are found. Telomeric heterochromatin is present in the largest autosomal pair and in two of the middle-sized autosomal pairs. The largest and smallest pairs of be-armed chromosomes do not have centromeric heterochromatin, whereas all the other autosomal pairs do. The presence of a NOR in 6 chromosomal pairs is established. Two of the pairs exhibited pericentromeric NORs, whereas the other 4 displayed telomeric NORs. The karyotype analysis illustrates the chromosome and genome polymorphism of A. agrarius in Bulgarian populations.

Range Dynamics of Striped Field Mouse (Apodemus agrarius) in Northern Eurasia under Global Climate Change Based on Ensemble Species Distribution Models

“…It follows from both our and the literature data that Bio_12 precipitation also influences species survival and reproduction [23], so this variable was also used to construct the SDMs. While the importance of variables Bio_01, Bio_02, Bio_05, and Bio_12 agrees with the published data [46,[118][119][120][121], the importance of variable Bio_19 is due to the presence of the winter precipitation threshold. On the one hand, the small amount of snow in winter provides thermal conditions for the SFM to overwinter in their burrows.…”

“…Overall, our study suggests that temperature (Bio_01) influences the survival and reproduction of A. agrarius [118][119][120][121]. Of course, other environmental variables, such as Bio_08 (mean temperature of wettest quarter, • C) and Bio_10 (mean temperature of warmest quarter, • C), can also effect A. agrarius reproduction, but these were not used because of the high Spearman correlation coefficient (Pspear) between Bio_01 and these variables (Pspear > 0.72, Figure S1).…”

“…Our analysis showed that among the variables that determine the iSDMs and eSDMs, four variables are the most important-Bio_01 (annual mean temperature), Bio_05 (max temperature of warmest month), Bio_12 (annual precipitation), and Bio_19 (precipitation of the coldest quarter). The importance of these variables for the species is confirmed by numerous studies conducted in the native and invasive parts of the range [46,[118][119][120]. Rodent reproductive activity is regulated by temperature, precipitation, and the availability of sufficient food [119].…”

“…The importance of these variables for the species is confirmed by numerous studies conducted in the native and invasive parts of the range [46,[118][119][120]. Rodent reproductive activity is regulated by temperature, precipitation, and the availability of sufficient food [119]. The temperature of the environment can have a strong influence on the reproductive rates of A. agrarius.…”

中国姬鼠属的核型研究

“…Apodemus chevrieri is restricted to southwestern China and based on mitochondrial and nuclear gene phylogenetic studies is thought to be a sister or in-group species of the widely distributed A. agrarius ( Liu et al, 2004 ; Suzuki et al, 2003 , 2008 ). Although the karyotype of A. agrarius is polymorphic and possesses 3–5 biarmed metacentric autosome pairs (2 n =48, FNa=52–56, excluding the B chromosome; Boeskorov et al, 1995 ; Britton-Davidian et al, 1991 ; Chassovnikarova et al, 2009 ; Chernukha et al, 1986 ; Kang & Koh, 1976 ; Kartavtseva, 1994 ; Kartavtseva & Pavlenko, 2000 ; Kefelioğlu et al, 2003 ; Koh, 1987 , 1988 , 1989 ; Král, 1970 , 1972 ; Matsubara et al, 2004 ; Shbulatova et al, 1991 ; Soldatović et al, 1969 , 1975 ; Tsuchiya, 1979 ; Vujošević et al, 1984 ; Wang et al, 1993 ; Yiğit et al, 2000 ), the karyotype with four metacentric pairs (2 n =48, FNa=54) is regarded as the standard karyotype for A. agrarius (see Kartavtseva & Pavlenko, 2000 ). Therefore, we suggest that there are no clear differences in the conventional karyotypes between A. chevrieri and A. agrarius ; however, further study using differential staining of chromosome arms is expected to clarify any minor differences and rearrangement of chromosome arms between A. chevrieri and polymorphic A. agrarius , and thus help reevaluate their taxonomic status.…”