Comparative Study of the Karyotypes of Two Species of Water Vole:<i>Arvicola Sapidus</i>and<i>Arvicola Terrestris</i>(Rodentia, Microtinae)

Arvicolid rodents present both synaptic and asynaptic sex chromosomes. We analyzed the pairing behaviour of sex chromosomes in two species belonging to this rodent group (Microtus nivalis and Arvicola sapidus). At pachynema, the sex chromosomes of both species paired in a small region while the rest remain unsynapsed. Consequently at metaphase I, sex chromosomes present end-to-end association. Thus, the pairing behaviour of sex chromosomes in these species is very similar to that previously described for other arvicolid rodents and for most mammals. According to this, we propose that synaptic sex chromosomes were the ancestral condition in the family Arvicolidae, including the genus Microtus. The phylogenetic origin of the asynaptic sex chromosomes in the genus Microtus would have arisen once in the lineage that originated the species M. arvalis/agrestis and related species, while the lineage that originated the species M. oeconomous and related species conserved synaptic chromosomes. Furthermore, the phylogenetic relationships between the genus Microtus, Chionomys and Pitymys are discussed in relation to the synaptic behaviour of sex chromosomes.

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“…1b). These results coincide with those described previously by D íaz de la G uardia and P retel (1979) and by B urgos et al (1990).…”

Section: Resultssupporting

confidence: 94%

Sex chromosomes pairing in two Arvicolidae species: Microtus nivalis and Arvicola sapidus

et al. 2003

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“…However, in A. sapidus, a more distant species, the painting revealed a banding pattern on the X chromosome which resembles the G-banding pattern for this chromosome (Dı´az de la Guardia & Pretel 1979, Burgos et al 1988a, Sa¤ nchez et al 1989. These results imply that, during the evolution of X chromosomes in Microtidae species, there has been a high conservation of euchromatic regions, although sporadic additions and deletions of chromosome regions occurred, which explains the autosomal bands in some species and the banding pattern on the X chromosome of A. sapidus.…”

Section: Discussionmentioning

confidence: 93%

X chromosome painting in Microtus: Origin and evolution of the giant sex chromosomes

et al. 2004

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Sex chromosomes in species of the genus Microtus present some characteristic features that make them a very interesting group to study sex chromosome composition and evolution. M. cabrerae and M. agrestis have enlarged sex chromosomes (known as 'giant sex chromosomes') due to the presence of large heterochromatic blocks. By chromosome microdissection, we have generated probes from the X chromosome of both species and hybridized on chromosomes from six Microtus and one Arvicola species. Our results demonstrated that euchromatic regions of X chromosomes in Microtus are highly conserved, as occurs in other mammalian groups. The sex chromosomes heterochromatic blocks are probably originated by fast amplification of different sequences, each with an independent origin and evolution in each species. For this reason, the sex heterochromatin in Microtus species is highly heterogeneous within species (with different composition for the Y and X heterochromatic regions in M. cabrerae) and between species (as the composition of M. agrestis and M. cabrerae sex heterochromatin is different). In addition, the X chromosome painting results on autosomes of several species suggest that, during karyotypic evolution of the genus Microtus, some rearrangements have probably occurred between sex chromosomes and autosomes.

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“…The G-banding karyotype of Arvicola sapidus and G-and C-banding karyotypes of Microtus nivalis have been previously described by Diaz de la Guardia & Pretel (1979) and Diaz de la Guardia et al (1981) respectively. Therefore, we wil only report the karyotypes of these two species (Figs.…”

Section: Resultsmentioning

confidence: 99%

“…Within the genus Arvicola, the karyotypes of A. sapidus and A. terrestris are evolutionarily close. They diverge only in two centric fusions (Diaz de la Guardia & Pretel, 1979). On the other hand, within the genus Microtus, a close cytological relationship exists between M. nivalis and M. cabrerae, while M. arvalis shows a major evolutionary divergence.…”

Section: Discussionmentioning

confidence: 99%

Comparative study of G- and C-banded chromosomes of five species of Microtidae

1986

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G-banded karyotypes were compared in the following species of Microtidae: Microtus nivalis; M. cabrerae; M. arvalis and Arvicola sapidus. Previous observations on A. sapidus and A. terrestris (Diaz de la Guardia & Pretel, Caryologia 32: 183-189, 1979) were also incorporated in this study. The results show that Robertsonian translocations and pericentric inversions are common mechanisms involved in the karyotypic evolution of this group. Interspecific differences in C-banding patterns were also analyzed. Using the karyograph method (Imai et al., Am. Nat. 121: 477-488, 1983), the evolutionary distances of the karyotypes were estimated, and an attempt was made to establish a presumptive phylogenetic tree.

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Comparative Study of the Karyotypes of Two Species of Water Vole:Arvicola SapidusandArvicola Terrestris(Rodentia, Microtinae)

Cited by 13 publications

References 9 publications

Sex chromosomes pairing in two Arvicolidae species: Microtus nivalis and Arvicola sapidus

Sex chromosomes pairing in two Arvicolidae species: Microtus nivalis and Arvicola sapidus

X chromosome painting in Microtus: Origin and evolution of the giant sex chromosomes

Comparative study of G- and C-banded chromosomes of five species of Microtidae

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