학술논문
Parallel occurrence of asynaptic sex chromosomes in gray voles (Microtus Schrank, 1798)
Document Type
Academic Journal
Author
Source
Paleontological Journal. December 4, 2013, Vol. 47 Issue 9, p1035, 6 p.
Subject
Language
English
ISSN
0031-0301
Abstract
GENERAL PATTERNS OF SEX CHROMOSOME EVOLUTION The phenomenon of parallelism is well known in the evolution of animals and plants and is finely studied. It is believed that parallelisms occurred [...]
In many eutherian species, pairing and recombination of X and Y chromosomes are indispensable for normal meiotic progression and correct segregation of sex chromosomes. The rodent subfamily Arvicolinae provides an interesting exception. The majority of arvicoline species with asynaptic sex chromosomes belong to the genus Microtus sensu lato. However, some vole species of the genus Microtus and other genera display normal X--Y pairing in meiosis. These observations indicate that synaptic condition was typical for the common ancestor of all voles, but the gaps in taxonomic sampling makes impossible to identify a lineage or lineages, in which the asynapsis occurred. The methods of electron and fluorescent microscopy were used to study the synapsis of sex chromosomes in males of some additional species of the subfamily Arvicolinae. This extended taxonomic list allowed us to identify asynaptic species in every large lineage of the tribe Microtini. Apparently, the ability of sex chromosomes to pair and recombine in male meiosis was lost in arvicoline evolution for at least three times independently. Our results indirectly suggest the unnecessity of sex chromosome pairing in male meiosis of arvicoline rodents, and presence of alternate molecular mechanism of sex chromosome segregation in this large mammalian tribe. Keywords: X and Y chromosomes, Microtus, asynapsis DOI:10.1134/S0031030113090049
In many eutherian species, pairing and recombination of X and Y chromosomes are indispensable for normal meiotic progression and correct segregation of sex chromosomes. The rodent subfamily Arvicolinae provides an interesting exception. The majority of arvicoline species with asynaptic sex chromosomes belong to the genus Microtus sensu lato. However, some vole species of the genus Microtus and other genera display normal X--Y pairing in meiosis. These observations indicate that synaptic condition was typical for the common ancestor of all voles, but the gaps in taxonomic sampling makes impossible to identify a lineage or lineages, in which the asynapsis occurred. The methods of electron and fluorescent microscopy were used to study the synapsis of sex chromosomes in males of some additional species of the subfamily Arvicolinae. This extended taxonomic list allowed us to identify asynaptic species in every large lineage of the tribe Microtini. Apparently, the ability of sex chromosomes to pair and recombine in male meiosis was lost in arvicoline evolution for at least three times independently. Our results indirectly suggest the unnecessity of sex chromosome pairing in male meiosis of arvicoline rodents, and presence of alternate molecular mechanism of sex chromosome segregation in this large mammalian tribe. Keywords: X and Y chromosomes, Microtus, asynapsis DOI:10.1134/S0031030113090049