Chromosome Asynapsis Is the Main Cause of Male Sterility in the Interspecies Hybrids of East Asian Voles (, Rodentia, Arvicolinae).

Closely related mammalian species often have differences in chromosome number and morphology, but there is still a debate about how these differences relate to reproductive isolation. To study the role of chromosome rearrangements in speciation, we used the gray voles in the genus as a model. These voles have a high level of chromosome polymorphism and substantial karyotypic divergence.

Negative heterosis for meiotic recombination rate in spermatocytes of the domestic chicken Gallus gallus.

Benef its and costs of meiotic recombination are a matter of discussion. Because recombination breaks allele combinations already tested by natural selection and generates new ones of unpredictable f itness, a high recombination rate is generally benef icial for the populations living in a f luctuating or a rapidly changing environment and costly in a stable environment. Besides genetic benef its and costs, there are cytological effects of recombination, both positive and negative.

Reproductive Isolation Between Taxonomically Controversial Forms of the Gray Voles (, Rodentia; Arvicolinae): Cytological Mechanisms and Taxonomical Implications.

The formation of hybrid sterility is an important stage of speciation. The voles of the genus , which is the most speciose genus of rodents, provide a good model for studying the cytological mechanisms of hybrid sterility. The voles of the "" group of the subgenus (2 = 54) comprising several recently diverged forms with unclear taxonomic status are especially interesting.

Homogeneously Staining Regions (HSR) in Chromosome 1 of the House Mouse: Synapsis and Recombination at Meiosis.

Amplified sequences constitute a large part of mammalian genomes. A chromosome 1 containing 2 large (up to 50 Mb) homogeneously staining regions (HSRs) separated by a small inverted euchromatic region is present in many natural populations of the house mouse (Mus musculus musculus). The HSRs are composed of a long-range repeat cluster, Sp100-rs, with a repeat length of 100 kb.